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Tutorial and Articles about ASP.NET and the latest ASP.NET Core

ASP.NET Core Hosting - Using Layered Architectures In ASP.NET

clock September 7, 2018 11:57 by author Kenny

One approach to designing Web applications is to focus on clearly defined layers of the application’s architecture. This approach is similar to the way an architect designs a building. If you’ve ever seen detailed construction plans for a skyscraper, you know the construction plans include separate blueprints for the foundation, frame, roof, plumbing, electrical, and other floors of the building.

With a layered architecture, specialists can design and develop the “floors” — called layers — independently, provided that the connections between the layers (the interfaces) are carefully thought out.

The layers should be independent of one another, as much as possible. Among other things, that means heeding a few must-dos and shalt-nots:

Each layer must have a clearly defined focus. To design the layers properly, you must clearly spell out the tasks and responsibilities of each layer.

Layers should mind their own business. If one layer is responsible for user interaction, only that layer is allowed to communicate with the user. Other layers that need to get information from the user must do so through the User Interface Layer.

Clearly defined protocols must be set up for the layers to interact with one another. Interaction between the layers occurs only through these protocols.

Note that the layers are not tied directly to any particular application. For example, an architecture might work equally well for an online ordering system and for an online forum. As a result, layered architecture has nothing to do with the ERDs that define a database or the Data Flow Diagrams that define how the data flows within the application. It’s a separate structure.

HOW MANY LAYERS?

There are several common approaches to application architecture that vary depending on the number of layers used. One common scheme is to break the application into two layers:

Application Layer: The design of the user interface and the implementation of business policies are handled in this layer. This layer may also handle transaction logic — the code that groups database updates into transactions and ensures that all updates within a transaction are made consistently.

Data Access Layer: The underlying database engine that supports the application. This layer is responsible for maintaining the integrity of the database. Some or all the transaction logic may be implemented in this layer.

In the two-layer model, the Application Layer is the ASP.NET Web pages that define the pages presented to the user as well as the code-behind files that implement the application’s logic. The Data Access Layer is the database server that manages the database, such as Microsoft SQL Server or Oracle.

Note that ASP.NET 2.0 doesn’t require that you place the application’s logic code in a separate code-behind file. Instead, you can intersperse the logic code with the presentation code in the same file. However, it’s almost always a good idea to use separate code-behind files to separate the application’s logic from its presentation code. All of the applications presented in this book use separate code-behind files.

The division between the Application and Data Access layers isn’t always as clear-cut as it could be. For performance reasons, transaction logic is often shifted to the database server (in the form of stored procedures), and business rules are often implemented on the database server with constraints and triggers. Thus, the database server often handles some of the application logic.

If this messiness bothers you, you can use a three-layer architecture, which adds an additional layer to handle business rules and policies:

Presentation Layer: This layer handles the user interface.

Business Rules Layer: This layer handles the application’s business rules and policies. For example, if a sales application grants discounts to certain users, the discount policy is implemented in this layer.

Data Access Layer: The underlying database model that supports the application.

Creating a separate layer for business rules enables you to separate the rules from the database design and the presentation logic. Business rules are subject to change. By placing them in a separate layer, you have an easier task of changing them later than if they’re incorporated into the user interface or database design.

MODEL-VIEW-CONTROLLER

Another common model for designing Web applications is called Model-View-Controller (MVC). In this architecture, the application is broken into three parts:

Model: The model is, in effect, the application’s business layer. It usually consists of objects that represent the business entities that make up the application, such as customers and products.

View: The view is the application’s user interface. In a Web application, this consists of one or more HTML pages that define the look and feel of the application.

Controller: The controller manages the events processed by the application. The events are usually generated by user-interface actions, such as the user clicking a button or selecting an item from a drop-down list.

In a typical ASP.NET application, the .aspx file implements the view; the model and controller functions are combined and handled by the code-behind file. Thus, the code-behind file can be thought of as the model-controller.

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ASP.NET Core Hosting - Queues In .NET Core

clock August 24, 2018 11:39 by author Kenny

I was recently looking into the new Channel<T>  API in .NET Core (For an upcoming post), but while writing it up, I wanted to do a quick refresher of all the existing “queues” in .NET Core. These queues are also available in full framework (And possibly other platforms), but all examples are written in .NET Core so your mileage may vary if you are trying to run them on a different platform.

FIFO vs LIFO

Before we jump into the .NET specifics, we should talk about the concept of FIFO or LIFO, or “First In, First Out” and “Last In, Last Out”. For the concept of queues, we typically think of FIFO. So the first message put into the queue, is the first one that comes out. Essentially processing messages as they go into a queue. The concept of LIFO, is typically rare when it comes to queues, but in .NET there is a type called Stack<T>  that works with LIFO. That is, after filling the stack with messages/objects, the last one put in would then be the first one out. Essentially the order would be reversed.

Queue<T>

Queue<T>  is going to be our barebones simple queue in .NET Core. It takes messages, and then pops them out in order. Here’s a quick code example :

static void Main(string[] args)
{
    Queue<string> messageQueue = new Queue<string>();
    messageQueue.Enqueue("Hello");
    messageQueue.Enqueue("World!");
 
    Console.WriteLine(messageQueue.Dequeue());
    Console.WriteLine(messageQueue.Dequeue());
    Console.ReadLine();
}

Pretty stock standard and not a lot of hidden meaning here. The Enqueue  method puts a message on our queue, and the Dequeue  method takes one off (In a FIFO manner). Our console app obviously prints out two lines, “Hello” then “World!”.

Barring multi threaded scenarios (Which we will talk about shortly), you’re not going to find too many reasons to use this barebones queue. In a single threaded app, you might pass around a queue to process a “list” of messages, but you may find that using a List<T>  within a loop is a simpler way of achieving the same result. Infact if you look at the source code of Queue, you will see it’s actually just an implementation of IEnumerable anyway!

So how about multi threaded scenarios? It kind of makes sense that you may want to load up a queue with items, and then have multiple threads all trying to process the messages. Well using a queue in this manner is actually not threadsafe, but .NET has a different type to handle multi threading…

ConcurrentQueue<T>

ConcurrentQueue<T>  is pretty similar to Queue<T> , but is made threadsafe by a copious amount of spinlocks. A common misconception is that ConcurrentQueues are just a wrapper around a queue with the use of the lock  keyword. A quick look at the source code here shows that’s definitely not the case. Why do I feel the need to point this out? Because I often see people try and make their use of Queue<T>  threadsafe by using locks, thinking that they are doing what Microsoft does when using ConcurrentQueue, but that’s pretty far from the truth and actually takes a pretty big performance hit when doing so.

Here’s a code sample of a ConcurrentQueue :

static void Main(string[] args)
{
    ConcurrentQueue<string> concurrentQueue = new ConcurrentQueue<string>();
    concurrentQueue.Enqueue("Hello");
    concurrentQueue.Enqueue("World!");
 
    string message;
    while(concurrentQueue.TryDequeue(out message))
    {
        Console.WriteLine(message);
    }
 
    Console.ReadLine();
}

So you’ll notice we can no longer just dequeue a message, we need to TryDequeue. It will return true if we managed to pop a message, and false if there is no message to pop.

Again, the main point of using a ConcurrentQueue over a regular Queue is that it’s threadsafe to have multiple consumers (Or producers/enqueuers) all using it at the same time.

BlockingCollection<T>

A blocking collection is an interesting “wrapper” type that can go over the top of any IProducerConsumerCollection<T>  type (Of which Queue<T>  and ConcurrentQueue<T>  are both). This can be handy if you have your own implementation of a queue, but for most cases you can roll with the default constructor of BlockingCollection. When doing this, it uses a ConcurrentQueue<T> under the hood making everything threadsafe (See source code here). The main reason to use a BlockingCollection is that it has a limit to how many items can sit in the queue/collection. Obviously this is beneficial if your producer is much faster than your consumers.

Let’s take a quick look :

static void Main(string[] args)
{
    BlockingCollection<string> blockingCollection = new BlockingCollection<string>(2);
    Console.WriteLine("Adding Hello");
    blockingCollection.Add("Hello");
    Console.WriteLine("Adding World!");
    blockingCollection.Add("World!");
    Console.WriteLine("Adding Good");
    blockingCollection.Add("Good");
    Console.WriteLine("Adding Evening");
    blockingCollection.Add("Evening!");
 
    Console.ReadLine();
}

What will happen with this code? You will see “Adding Hello”, “Adding World!”, and then nothing… Your application will just hang. The reason is this line :

BlockingCollection<string> blockingCollection = new BlockingCollection<string>(2);

We’ve initialized the collection to be a max size of 2. If we try and add an item where the collection is already at this size, we will just wait until a message is dequeued. How long will we wait? Well by default, forever. However we can change our add line to be :
blockingCollection.TryAdd("Hello", TimeSpan.FromSeconds(60));

So we’ve changed our Add call to TryAdd, and we’ve specified a timespan to wait. If this timespan is hit, then the TryAdd method will return false to let us know we weren’t able to add the item to the collection. This is handy if you need to alert someone that your queue is overloaded (e.g. the consumers are stalled for whatever reason).

Stack<T>

As we talked about earlier, a Stack<T> type allows for a Last In, First Out (LIFO) queuing style. Consider the following code :

static void Main(string[] args)
{
    Stack<string> stack = new Stack<string>();
    stack.Push("Hello");
    stack.Push("World!");
 
    Console.WriteLine(stack.Pop());
    Console.WriteLine(stack.Pop());
 
    Console.ReadLine();
}

The output would be “World!” then “Hello”. It’s rare that you would need this reversal of messages, but it does happen. Stack<T>  also has it’s companion in ConcurrentStack<T> , and you can initialize BlockingCollection with a ConcurrentStack within it. 

Best ASP.NET Hosting Recommendation

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ASP.NET Core Hosting - Easy to Migrate Visual Basic 6 to .NET

clock August 21, 2018 09:56 by author Kenny

Converting VB6 code to VB.NET is not a simple process that can be executed easily in spite of using automation tools. A number of automation tools are available in the market, with Microsoft itself being shipped with Visual Basic Upgrade Wizard. Some of the major changes undergone in VB6 is in the Common Language Runtime (CLR) new programming model. To reap maximum benefit out of the new features and structures of VB.NET, it is advisable to rewrite major sections of the application than porting it. Since this is a tedious process you can use VB.NET’s Upgrade Wizard that automatically converts all the syntaxes, which is just half the work done. No sooner you will be faced with other problems and errors during compilation that won’t be handled properly with the Upgrade Wizard. During migration you will have to rewrite and rearchitect the codes to take maximum advantage of VB.NET’s new tools.

.NET migration is a complex process that requires strict adherence to the features and syntactical aspects of the programming language. Here we list some of the essential steps that need to be considered while migrating from VB6 to VB.NET.

1. Application Assessment – Perform a thorough assessment of the application to be upgraded. You can document the existing system functionalities, which may be a tedious process. Use an assessment tool to analyze the VB6 application to understand issues and estimate the approximate cost and effort.

2. Planning and Preparation – Prepare project plan, determine scope and migration requirements by elucidating maximum information about the application. Create functional requirements for the new framework and application.

3. Upgrade Strategies – Develop a migration strategy after brainstorming the application requirements. First you need to get the VB6 application into the new .NET platform with the existing functionality then perform incremental changes to incorporate new functions.

4. Automatic Upgrade Process – After automated migration the quality of the generated code needs to be improved. This involves removing duplicated code, upgrading problematic syntax and controls, fixing data declarations, and the like.

5. Manual Upgrade Process – It is essential to rewrite critical application logic to suit the .NET framework and those that have not been properly converted during automation. You can continue writing new code in VB.NET leaving the bulk of the existing code in VB6 as there is good interoperability between VB6 COM components and VB.NET components.

6. Migrate Data – This involves creating a SQL Server or database and importing data and resizing the database structure.

7. Compiling – Compiling the project gives a list of compilation errors and runtime errors that needs to be analyzed and fixed through an iterative process.

8. Fixing Errors – Bugs can be tracked using various source code analyzers that helps identify duplicate codes and fix data declarations.

9. Quality Assurance – Upgraded application will be subjected to different levels of testing throughout the process to ensure reliability and correctness of the application.

  • Unit test thoroughly each item converted to help identify any flaws in implementation.
  • Perform system testing to ensure the application functionalities are met in the .NET framework version.
  • Import final version legacy data and perform load testing to ensure the application works in the .NET environment.

10. Deployment – Finally deploy to application server and verify the checklist of all the components and functionalities in the application tally.

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ASP.NET Core 2 Hosting - Create ASP.NET Chart Control from Database using C#

clock August 10, 2018 11:11 by author Kenny

In this article I will explain with an example, how you can display charts in ASP.Net using new Chart Control.

Web.Config Modifications

You will need to modify the Web.Config file as following shown in order to use the ASP.Net 4.0 Chart control.

<configuration>
    <appSettings>
        <add key="ChartImageHandler" value="storage=file;timeout=20;" />
    </appSettings>
    <connectionStrings>
        <add name="conString"
        connectionString="Data Source=.\SQL2005;database=Northwind;Integrated Security=true"/>
    </connectionStrings>
 
    <system.web>
        <compilation debug="true" targetFramework="4.0">
            <assemblies>
                <add assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
            </assemblies>
        </compilation>
        <httpHandlers>
            <add path="ChartImg.axd" verb="GET,HEAD,POST" type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" validate="false"/>
        </httpHandlers>
        <pages>
            <controls>
                <add tagPrefix="asp" namespace="System.Web.UI.DataVisualization.Charting" assembly="System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
            </controls>
        </pages>
    </system.web>
    <system.webServer>
        <handlers>
            <remove name="ChartImageHandler"/>
            <add name="ChartImageHandler" preCondition="integratedMode" verb="GET,HEAD,POST" path="ChartImg.axd" type="System.Web.UI.DataVisualization.Charting.ChartHttpHandler, System.Web.DataVisualization, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35"/>
        </handlers>
    </system.webServer>
</configuration>

HTML Markup

Below is the HTML Markup of the page. It has an ASP.Net DropDownList and an ASP.Net Chart Control. The DropDownList is populated with countries and when a country is selected, the chart is populated with the statistics of orders of different cities in the selected country.

<asp:DropDownList ID="ddlCountries" runat="server" OnSelectedIndexChanged="ddlCountries_SelectedIndexChanged"
    AutoPostBack = "true">
</asp:DropDownList><hr />
<asp:Chart ID="Chart1" runat="server" Height="300px" Width="400px" Visible = "false">
    <Titles>
        <asp:Title ShadowOffset="3" Name="Items" />
    </Titles>
    <Legends>
        <asp:Legend Alignment="Center" Docking="Bottom" IsTextAutoFit="False" Name="Default" LegendStyle="Row" />
    </Legends>
    <Series>
        <asp:Series Name="Default" />
    </Series>
    <ChartAreas>
        <asp:ChartArea Name="ChartArea1" BorderWidth="0" />
    </ChartAreas>
</asp:Chart>

Namespaces

You will need to import the following Namespaces.

C#

using System.Data;
using System.Data.SqlClient;
using System.Configuration;

Populating the DropDownList and Chart

Inside the Page Load event, the DropDownList is populated with Countries from the Orders table of the Northwind database. When a Country is selected in the DropDownList, the statistical records of Ship Cities and their Total Orders are fetched from the Orders table. The Ship City values are assigned to the X point values of the Chart while the Total Orders value for the Ship Cities are assigned to the Y point values of the Chart. Finally using these values the Chart is populated and displayed.

C#

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        string query = "select distinct shipcountry from orders";
        DataTable dt = GetData(query);
        ddlCountries.DataSource = dt;
        ddlCountries.DataTextField = "shipcountry";
        ddlCountries.DataValueField = "shipcountry";
        ddlCountries.DataBind();
        ddlCountries.Items.Insert(0, new ListItem("Select", ""));
    }
}
  
protected void ddlCountries_SelectedIndexChanged(object sender, EventArgs e)
{
    Chart1.Visible = ddlCountries.SelectedValue != "";
    string query = string.Format("select shipcity, count(orderid) from orders where shipcountry = '{0}' group by shipcity", ddlCountries.SelectedValue);
    DataTable dt = GetData(query);
    string[] x = new string[dt.Rows.Count];
    int[] y = new int[dt.Rows.Count];
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        x[i] = dt.Rows[i][0].ToString();
        y[i] = Convert.ToInt32(dt.Rows[i][1]);
    }
    Chart1.Series[0].Points.DataBindXY(x, y);
    Chart1.Series[0].ChartType = SeriesChartType.Pie;
    Chart1.ChartAreas["ChartArea1"].Area3DStyle.Enable3D = true;
    Chart1.Legends[0].Enabled = true;
}
 
private static DataTable GetData(string query)
{
    DataTable dt = new DataTable();
    SqlCommand cmd = new SqlCommand(query);
    String constr = ConfigurationManager.ConnectionStrings["ConString"].ConnectionString;
    SqlConnection con = new SqlConnection(constr);
    SqlDataAdapter sda = new SqlDataAdapter();
    cmd.CommandType = CommandType.Text;
    cmd.Connection = con;
    sda.SelectCommand = cmd;
    sda.Fill(dt);
    return dt;
}

Best ASP.NET Hosting Recommendation
 

ASPHostPortal.com provides its customers with Plesk Panel, one of the most popular and stable control panels for Windows hosting, as free. You could also see the latest .NET framework, a crazy amount of functionality as well as Large disk space, bandwidth, MSSQL databases and more. All those give people the convenience to build up a powerful site in Windows server. ASPHostPortal.com offers ASP.NET hosting starts from $1/month only. They also guarantees 30 days money back and guarantee 99.9% uptime. If you need a reliable affordable ASP.NET Hosting, ASPHostPortal.com should be your best choice.



ASP.NET Core 2 Hosting - How to Secure Your .NET Core 2.0 Web App

clock August 3, 2018 11:29 by author Kenny

Configuring ASP.NET Core to require authentication

Imagine we’re starting with an ASP.NET Core 2.0 MVC application (with no authentication mechanism configured).

You can grab the code we’re about to go through and take a look for yourself using the next link.

Get the code: Simple Authentication using ASP.NET Core 2.0
The first step is to enable authentication for our site, which we can do by modifying startup.cs.

We can start by adding the relevant Authentication services to our application.

public void ConfigureServices(IServiceCollection services)
{
    services.AddAuthentication(CookieAuthenticationDefaults.AuthenticationScheme)
        .AddCookie(CookieAuthenticationDefaults.AuthenticationScheme,
            options =>
            {
                options.LoginPath = new PathString("/auth/login");
                options.AccessDeniedPath = new PathString("/auth/denied");
            });
     // ---------------
     // rest of configureServices code goes here...
}

We’re going to stick with cookies for now. This means our logged in users will get a cookie in their browser, which gets passed to our app on every request, indicating that they are authenticated.

Notice how we’ve configured two paths, the path to the login page (where we can send unauthenticated people when they try to access a restricted area) and the path to an access denied page (useful for when they inevitably enter incorrect credentials).

We also need to tell our app to go ahead and actually enable authentication. Happily, this is very very simple in .NET Core 2…

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseAuthentication();
    // ---------------
    // rest of configure code goes here...
}

Just another Login form

So now our app knows we’re going to be using authentication, but there’s more work to be done.

We need a way to identify our users, the common way being to ask them for a username and password.

Login forms are straightforward enough, here’s one to get us started.

<h2>Hmm, looks like you need to log in</h2>
<form asp-controller="Auth" asp-action="Login" method="post">
    <label for="username">Username</label>
    <input id="username" name="username" type="text"/>
    <label for="password">Password</label>
    <input id="password" name="password" type="password" />
    <button type="submit">Log me in</button>
</form>

If we’re using the default routing for MVC, you’ll want to create an AuthController with a Login action that returns this view.

If you’re not familiar with them, the asp- attributes are tag helpers, new to ASP.NET core, which make it easier to link your html to your ASP.NET MVC controllers. Read more about tag helpers here.

In this example, the form contents will be posted to the Login action on an Auth controller.

A word to the wise, if you start with an empty web app project you’ll find that Tag Helpers don’t work automatically.

The easiest way to get them working is to create a _ViewImports.cshtml file and add this line to it…

@addTagHelper *, Microsoft.AspNetCore.Mvc.TagHelpers

If you start with one of the other starter templates you’ll probably find this file is created for you.

The logging in bit

To keep this super, super simple, we’ll opt to hard-code a username and password for now.

If our users enter the correct combination, they’ll be logged in, with full access to “locked down” parts of the application.

Now let’s be honest, hardcoded usernames and passwords are somewhat limiting (and not at all secure if your code ends up in a public Github repo) but they do tackle our urgent requirement to provide a mechanism for users to log in, and gain access to parts of the site that will be unavailable to Joe Public.

This falls into the camp of “doing the simplest possible thing first”, so you can start to build up momentum with your new app, rather than getting bogged down in building your own user management system from day one.

The login form will post to this controller action…

[HttpPost, ValidateAntiForgeryToken]
public async Task<IActionResult> Login(string returnUrl, string username, string password)
{
    if (username == "Jon" && password == "ABitSimplisticForProductionUseThis...")
    {
        var claims = new List<Claim>
        {
            new Claim(ClaimTypes.Name, "jon", ClaimValueTypes.String, "
https://yourdomain.com")
        };
        var userIdentity = new ClaimsIdentity(claims, "SecureLogin");
        var userPrincipal = new ClaimsPrincipal(userIdentity);
        await HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme,
            userPrincipal,
            new AuthenticationProperties
            {
                ExpiresUtc = DateTime.UtcNow.AddMinutes(20),
                IsPersistent = false,
                AllowRefresh = false
            });
        return GoToReturnUrl(returnUrl);
    }
    return RedirectToAction(nameof(Denied));
}

There’s our super insecure hardcoded username/password check (as discussed).

We’ve opted to use claims-based security.

In the most basic sense, you can think of Claims as pieces of information about your user. In this case we’re simply storing the user’s name in a claim, which we then attach to an identity for the user.

This identity is the representation of your user that ASP.NET core can interrogate, to find out anything it needs to know.

You can assign many claims to one identity, but ASP.NET Core requires the name claim as a minimum requirement (it will error if you don’t assign one).

Next up we create a user principal. If this is your first foray into ASP.NET Core authentication then this can be a little confusing, but it’s worth noting you could have more than one identity and attach them all to the same principal.

We’ve no need to handle multiple identities for the same user yet, so we can move along to the SignInAsync method on the HTTPContext, which logs our user in.

In practice, this creates an encrypted cookie holding the user’s information (the Claims Principal). From here on (until they exit the browser) your user is authenticated.

Because we’ve set IsPersistent to false, the cookie will be lost when our user exits their browser, and will have to log in again next time they come to the site.

If you want to see what that cookie looks like, check out the Application > Cookies window in Chrome (you’ll find a similar view in other browsers) and you’ll find it there, called .AspNetCore.Cookies.
Once they’re logged in, the user is redirected to the original page they requested, or the home page. You can do this with a simple helper method.

private IActionResult GoToReturnUrl(string returnUrl)
{
    if (Url.IsLocalUrl(returnUrl))
    {
        return Redirect(returnUrl);
    }
    return RedirectToAction("Index", "Home");
}

No access for you

This is all well and good, but currently there’s no reason for anyone to log in to the site, because nothing is locked down.

Let’s remedy that by restricting access to the main homepage for the app.

[Authorize]
public class HomeController : Controller
{
    public IActionResult Index()
    {
        return View();
    }
}

The [Authorize] attribute will trigger ASP.NET Core to redirect any users who aren’t logged in (don’t have an auth cookie) to the login page (that we configured in startup.cs).

It’s all about you

So that’s almost the entire process. But it would be nice to greet the user by name.

We’ll do this on our main index view…

<h1>Hi @User.Identity.Name, you're in the club.</h1>    

Let me out of here

Finally, we should probably let them log out, if they so wish.

All this needs is a simple form.

<form asp-controller="Auth" asp-action="Logout">
    <button type="submit">Log out</button>
</form>
And controller action.
public async Task<IActionResult> Logout()
{
    await HttpContext.SignOutAsync();
    return RedirectToAction(nameof(Login));
}

Best ASP.NET Hosting Recommendation
 

ASPHostPortal.com provides its customers with Plesk Panel, one of the most popular and stable control panels for Windows hosting, as free. You could also see the latest .NET framework, a crazy amount of functionality as well as Large disk space, bandwidth, MSSQL databases and more. All those give people the convenience to build up a powerful site in Windows server. ASPHostPortal.com offers ASP.NET hosting starts from $1/month only. They also guarantees 30 days money back and guarantee 99.9% uptime. If you need a reliable affordable ASP.NET Hosting, ASPHostPortal.com should be your best choice.



ASP.NET Core 2 Hosting - How to Use Bootstrap 4 in ASP.NET Core

clock July 31, 2018 08:47 by author Kenny

 So although you can still use it right now, Bootstrap has also announced to drop support for it. As a result, the built-in ASP.NET Core templates are slowly being edited to move away from it too.

Unfortunately, there is no clear path forward. This is mostly due to the fact that web applications are continuously moving further into the client-side, requiring complex client-side build systems and many dependencies. So if you are building something like that, you might already know how to solve this then, and you can expand your existing build process to simply also include Bootstrap and jQuery there.

But there are still many web applications out there that are not that heavy on the client-side, where the application still runs mainly on the server and the server serves static views as a result. Bower previously filled this by making it easy to just publish client-side dependencies without that much of a process.

In the .NET world we also have NuGet and with previous ASP.NET versions, we could use NuGet as well to add dependencies to some client-side dependencies since NuGet would just place the content into our project correctly. Unfortunately, with the new .csproj format and the new NuGet, installed packages are located outside of our project, so we cannot simply reference those.

This leaves us with a few options how to add our dependencies:

One-time installation

This is what the ASP.NET Core templates, that are not single-page applications, are currently doing. When you use those to create a new application, the wwwroot folder simply contains a folder lib that contains the dependencies:

If you look closely at the files currently, you can see that they were originally placed there with Bower to create the template, but that is likely to change soon. The basic idea is that the files are copied once to the wwwroot folder so you can depend on them.

To do this, we can simply follow Bootstrap’s introduction and download the compiled files directly. As mentioned on the download site, this does not include jQuery, so we need to download that separately too; it does contain Popper.js though if we choose to use the bootstrap.bundle file later—which we will do. For jQuery, we can simply get a single "compressed, production" file from the download site.

This leaves us with a few files which will simply extract and copy into the wwwroot folder. We can also make a lib folder to make it clearer that these are external dependencies:

That’s all we need, so now we just need to adjust our _Layout.cshtml file to include those dependencies. For that, we add the following block to the <head>:

<environment include="Development">
<link rel="stylesheet" href="~/lib/css/bootstrap.css" />
</environment>
<environment exclude="Development">
<link rel="stylesheet" href="~/lib/css/bootstrap.min.css" />
</environment>

And the following block at the very end of the <body>:

<environment include="Development">
<script src="~/lib/js/jquery-3.3.1.js"></script>
<script src="~/lib/js/bootstrap.bundle.js"></script>
</environment>
<environment exclude="Development">
<script src="~/lib/js/jquery-3.3.1.min.js"></script>
<script src="~/lib/js/bootstrap.bundle.min.js"></script>
</environment>

You can also just include the minified versions and skip the <environment> tag helpers here to make it a bit simpler. But that’s all you need to do to keep you starting.

Dependencies from NPM

The more modern way, also if you want to keep your dependencies updated, would be to get the dependencies from the NPM package repository. You can use either NPM or Yarn for this; in my example, I’ll use NPM.

To start off, we need to create a package.json file for our project, so we can specify our dependencies. To do this, we simply do that from the "Add New Item" dialog:

Once we have that, we need to edit it to include our dependencies. It should something look like this:

{
"version": "1.0.0",
"name": "asp.net",
"private": true,
"devDependencies": {
"bootstrap": "4.0.0",
"jquery": "3.3.1",
"popper.js": "1.12.9"
}
}

By saving, Visual Studio will already run NPM to install the dependencies for us. They will be installed into the node_modules folder. So what is left to do is to get the files from there into our wwwroot folder. There are a few options to do that:

bundleconfig.json for bundling and minification

We can use one of the various ways to consume a bundleconfig.json for bundling and minification, as explained in the documentation. A very easy way is to simply use the BuildBundlerMinifier NuGet package which automatically sets up a build task for this.

After installing that package, we need to create a bundleconfig.json at the root of the project with the following contents:

[
{
"outputFileName": "wwwroot/vendor.min.css",
"inputFiles": [
"node_modules/bootstrap/dist/css/bootstrap.min.css"
],
"minify": { "enabled": false }
},
{
"outputFileName": "wwwroot/vendor.min.js",
"inputFiles": [
"node_modules/jquery/dist/jquery.min.js",
"node_modules/popper.js/dist/umd/popper.min.js",
"node_modules/bootstrap/dist/js/bootstrap.min.js"
],
"minify": { "enabled": false }
}
]

This basically configures which files to combine into what. And when we build, we can see that the vendor.min.css and vendor.js.css are created correctly. So all we need to do is to adjust our _Layouts.html again to include those files:

<!-- inside <head> -->
<link rel="stylesheet" href="~/vendor.min.css" />
<!-- at the end of <body> -->
<script src="~/vendor.min.js"></script>

Using a task manager like Gulp

If we want to move a bit more into client-side development, we can also start to use tools that we would use there. For example Webpack which is a very commonly used build tool for really everything. But we can also start with a simpler task manager like Gulp and do the few necessary steps ourselves.

For that, we add a gulpfile.js into our project root, with the following contents:

const gulp = require('gulp');
const concat = require('gulp-concat');
const vendorStyles = [
"node_modules/bootstrap/dist/css/bootstrap.min.css"
];
const vendorScripts = [
"node_modules/jquery/dist/jquery.min.js",
"node_modules/popper.js/dist/umd/popper.min.js",
"node_modules/bootstrap/dist/js/bootstrap.min.js",
];
gulp.task('default', ['build-vendor']);
gulp.task('build-vendor', ['build-vendor-css', 'build-vendor-js']);
gulp.task('build-vendor-css', () => {
return gulp.src(vendorStyles)
.pipe(concat('vendor.min.css'))
.pipe(gulp.dest('wwwroot'));
});
gulp.task('build-vendor-js', () => {
return gulp.src(vendorScripts)
.pipe(concat('vendor.min.js'))
.pipe(gulp.dest('wwwroot'));
});

Now, we also need to adjust our package.json to have dependencies on gulp and gulp-concat:

{
"version": "1.0.0",
"name": "asp.net",
"private": true,
"devDependencies": {
"bootstrap": "4.0.0",
"gulp": "^3.9.1",
"gulp-concat": "^2.6.1",
"jquery": "3.3.1",
"popper.js": "1.12.9"
}
}

Finally, we edit our .csproj to add the following task which makes sure that our Gulp task runs when we build the project:

<Target Name="RunGulp" BeforeTargets="Build">
<Exec Command="node_modules\.bin\gulp.cmd" />
</Target>

Now, when we build, the default Gulp task runs, which runs the build-vendor tasks, which then builds our vendor.min.css and vendor.min.js just like we did before. So after adjusting our _Layout.cshtml just like above, we can make use of jQuery and Bootstrap.

While the initial setup of Gulp is a bit more complicated than the bundleconfig.json one above, we have now have entered the Node-world and can start to make use of all the other cool tools there. So it might be worth to start with this.

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ASP.NET Hosting - ASPHostPortal.com :: Tips to Create Create WebGrid with Expand in ASP.NET MVC

clock September 6, 2016 19:53 by author Armend

Introduction

In this post, I am explain How to Create Nested WebGrid with Expand/Collapse in ASP.NET MVC 6.
Steps :

Step - 1 : Create New Project.

  • Go to File > New > Project > Select asp.net MVC6 web application > Entry Application Name > Click OK > Select Internet Application > Select view engine Razor > OK

Step-2: Add a Database.

  • Go to Solution Explorer > Right Click on App_Data folder > Add > New item > Select SQL Server Database Under Data > Enter Database name > Add.

Step-3: Create table for fetch data.

  • Open Database > Right Click on Table > Add New Table > Add Columns > Save > Enter table name > OK.

In this example, I have used two tables as below

Step-4: Add Entity Data Model.

  • Go to Solution Explorer > Right Click on Project name form Solution Explorer > Add > New item > Select ADO.net Entity Data Model under data > Enter model name > Add.
  • A popup window will come (Entity Data Model Wizard) > Select Generate from database > Next >
  • Chose your data connection > select your database > next > Select tables > enter Model Namespace > Finish.

Step-5: Add a class for create a view model.

  • 1st : Add a folder.
  • Go to Solution Explorer > Right Click on the project > add > new folder.
  • 2nd : Add a class on that folder
  • Go to Solution Explorer > Right Click on that folder > Add > Class... > Enter Class name > Add.

Write the following code in this class

using System.Collections.Generic;
namespace MVCNestedWebgrid.ViewModel
{
    public class OrderVM
    {
        public OrderMaster order { get; set; }
        public List<OrderDetail> orderDetails { get; set; }
    }
}

Step-6: Add a new Controller.

  • Go to Solution Explorer > Right Click on Controllers folder form Solution Explorer > Add > Controller > Enter Controller name > Select Templete "empty MVC Controller"> Add.

Step-7: Add new action into your controller for show nested data in a webgrid.

Here I have added "List" Action into "Order" Controller. Please write this following code

public ActionResult List()
{
    List<OrderVM> allOrder = new List<OrderVM>();
 
    // here MyDatabaseEntities is our data context
    using (MyDatabaseEntities dc = new MyDatabaseEntities())
    {
        var o = dc.OrderMasters.OrderByDescending(a => a.OrderID);
        foreach (var i in o)
        {
            var od = dc.OrderDetails.Where(a => a.OrderID.Equals(i.OrderID)).ToList();
            allOrder.Add(new OrderVM { order= i, orderDetails = od });
        }
    }
    return View(allOrder);
}

Step-8: Add view for the Action & design.

  • Right Click on Action Method (here right click on form action) > Add View... > Enter View Name > Select View Engine (Razor) > Check "Create a strong-typed view" > Select your model class > Add.

NOTE " Please Rebuild solution before add view

Html Code
@model IEnumerable<MVCNestedWebgrid.ViewModel.OrderVM>

@{
    ViewBag.Title = "Order List";
    WebGrid grid = new WebGrid(source: Model, canSort: false);
}
<div id="main" style="padding:25px; background-color:white;">
    @grid.GetHtml(
    htmlAttributes: new {id="gridT", width="700px" },
    columns:grid.Columns(
            grid.Column("order.OrderID","Order ID"),
            grid.Column(header:"Order Date",format:(item)=> string.Format("{0:dd-MM-yyyy}",item.order.OrderDate)),
            grid.Column("order.CustomerName","Customer Name"),
            grid.Column("order.CustomerAddress","Address"),
            grid.Column(format:(item)=>{
                WebGrid subGrid = new WebGrid(source: item.orderDetails);
                return subGrid.GetHtml(
                    htmlAttributes: new { id="subT" },
                    columns:subGrid.Columns(
                            subGrid.Column("Product","Product"),
                            subGrid.Column("Quantity", "Quantity"),
                            subGrid.Column("Rate", "Rate"),
                            subGrid.Column("Amount", "Amount")
                        )                   
                    );
            })
        )
    )
</div>
Css Code
<style>
th, td {
        padding:5px;
    }
    th
    {
        background-color:rgb(248, 248, 248);       
    }
    #gridT,  #gridT tr {
        border:1px solid #0D857B;
    }
    #subT,#subT tr {
        border:1px solid #f3f3f3;
    }
    #subT {
        margin:0px 0px 0px 10px;
        padding:5px;
        width:95%;
    }
    #subT th {
        font-size:12px;
    }
    .hoverEff {
        cursor:pointer;
    }
    .hoverEff:hover {
        background-color:rgb(248, 242, 242);
    }
    .expand {
        background-image: url(/Images/pm.png);
        background-position-x: -22px;
        background-repeat:no-repeat;
    }
    .collapse  {
        background-image: url(/Images/pm.png);
        background-position-x: -2px;
        background-repeat:no-repeat;
    }
</style>
Write the following Jquery code for make webgrid collapsible
<script>
    $(document).ready(function () {
        var size = $("#main #gridT > thead > tr >th").size(); // get total column
        $("#main #gridT > thead > tr >th").last().remove(); // remove last column
        $("#main #gridT > thead > tr").prepend("<th></th>"); // add one column at first for collapsible column
        $("#main #gridT > tbody > tr").each(function (i, el) {
            $(this).prepend(
                    $("<td></td>")
                    .addClass("expand")
                    .addClass("hoverEff")
                    .attr('title',"click for show/hide")
                );
            //Now get sub table from last column and add this to the next new added row
            var table = $("table", this).parent().html();
            //add new row with this subtable
            $(this).after("<tr><td></td><td style='padding:5px; margin:0px;' colspan='" + (size - 1) + "'>" + table + "</td></tr>");
            $("table", this).parent().remove();
            // ADD CLICK EVENT FOR MAKE COLLAPSIBLE
            $(".hoverEff", this).live("click", function () {
                $(this).parent().closest("tr").next().slideToggle(100);
                $(this).toggleClass("expand collapse");
            });
        });
        //by default make all subgrid in collapse mode
        $("#main #gridT > tbody > tr td.expand").each(function (i, el) {
            $(this).toggleClass("expand collapse");
            $(this).parent().closest("tr").next().slideToggle(100);
        });    
    });
</script>

 

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ASP.NET Hosting - ASPHostPortal.com :: ASP.NET MVC vs ASP.NET - Which is better?

clock June 3, 2016 22:54 by author Dan

When developers start to build new web projects they face two options- either using ASP.NET MVC framework or ASP.NET web forms. These days, more and more companies are however choosing the MVC based framework to revise their existing sites significantly or to develop new ones. The framework has a multitude of benefits as well as technical goodies which have made it the darling among the developers.

MVC, short for Model-View-Controller is an architectural pattern that helps in division of an application into three basic components- the controller, the model and the view. This framework is a great alternative to the web forms pattern when creating applications since it is highly testable as well as lightweight presentation framework. It comes integrated with all current .NET features like authentication based on membership as well as master pages. Most developers are quite familiar with the pattern. Here is a low-down on the advantages that the MVC based framework offers over the web forms.

Separating application tasks or concerns- A huge advantage in the framework is that it clearly separates Business Logic, Data, Model, UI, test-driven development and testability. Core contracts of the framework are interface-based for which mock objects may be used for the testing. These mock objects are simulated objects imitating the behaviours of application's actual objects. The application can be unit-tested without making the controllers run, making the testing more flexible as well as fast. Any framework may be used for the testing.

Clientcaching

Silverlight makes this available to us. When we integrate Silverlight full advantage may be taken of the feature. This leads to faster application loading; in fact some part of processing may be done through web browsers, this makes the execution of client site as well as the server side a lot faster. You can even integrate JQuery and MVC so that the code written runs in browser, taking away a huge load away from the server.

HTML size

In ASP.NET there is a huge problem in the HTML size of view state as well as controls. All data rendered is stored by view state with the final result being the final HTML getting too large. For those on slow internet connections, the loading time will be slow as well as delayed. The current framework takes care of that problem since the view state concept is absent here.

Supporting ASP.NET routing

This URL-mapping component is very powerful, letting you build applications with searchable and comprehensible URLs. Through this there is no need for URLs to include extensions of file-names since the design supports patterns of URL naming and these work good enough for SEO or search engine optimization as well as REST or representational state transfer addressing.

Pluggable as well as extensible framework

The design of MVC's components makes them easily customizable or replaceable. Individual view engine, action-method parameter serialization, URL routing policy as well as other components can be plugged in. The use of DI or Dependency Injection and IOC or Inversion of Control container models is also supported. With DI you can inject objects into classes and it does not rely on class for creation of object itself. The testing is made easier by the condition imposed that when an object is required by another object then another object should be sourced from an external source like configuration file.

The biggest advantage of ASP.NET MVC platform is that it contains all the features as well as advantages of .NET since the basis is the same for both. However, some disadvantages are that understanding codes during the process of customization may not be an easy process. Another problem is the cost- the start-up costs are much higher in the MVC platform when compared to the web form based one. But looking at the benefits that are enjoyed by the developers and the end result, this is but a small price to pay for. You can get in touch with a asp.net application development company who can help you develop web apps that are stable, scalable and secure.

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ASP.NET Hosting - ASPHostPortal.com :: How to Check Duplicate User Names In ASP.NET Web Pages Sites

clock October 5, 2015 11:39 by author Kenny

How to Check Duplicate User Names In ASP.NET Web Pages Sites

The Web Pages Starter Site template provides a useful starting point for developing a Razor Web Pages site that includes membership. But it doesn't include any mechanism for preventing duplicate user names. This article offers one solution to the problem that uses jQuery.

If you ask how to prevent duplicate user names in forums, one of the suggestions that is often put forward is to apply a unique constraint in the database column that holds the user name. Any attempt to submit a duplicate value will result in an exception being raised in the relevant database provider. You can catch this exception and show the user an appropriate message. This works but it's a fairly clunky solution. And many people feel that you should not use exceptions as a means to manage your business rules.

The solution featured in this article uses AJAX to query the database and to give the user immediate feedback when they enter their chosen user name. The AJAX call requests a page that exists purely to query the database to see if the selected user name is already in use. The solution also includes a server side chekc to ensure that users who have disabled JavaScript so not slip through the net. The solution requires a couple of amendments to the Register.cshtml file in the Starter Site, and the addition of 3 files. But first, the changes to the Register.cshtml page. The first change is in the inclusion of a JavaScript file called dupecheck.js.

@* Remove this section if you are using bundling *@
@section Scripts {
    <script src="~/Scripts/jquery.validate.min.js"></script>
    <script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>
    <script src="~/Scripts/dupecheck.js"></script>
}

And the second is the server side check to see if the username is in use:

if(Functions.IsDuplicate(email)){
    ModelState.AddError("email", "User name is already taken");
}

I placed this in the if(IsPost) section just after the initial variables that represent the submitted values (email, password and confirmPassword) are declared. The code calls a function named IsDuplicate. The function is declared in a file called Functions.cshtml which is placed in a folder called App_Code:

@functions {
    public static bool IsDuplicate(string username){
        var db = Database.Open("StarterSite");
        var commandText = @"SELECT COUNT(Email) FROM UserProfile WHERE Email = @0";
        return (int)db.QueryValue(commandText, username) > 0;
    }
}

Note that the name of the folder is important. The function returns a bool. The value of the bool is determined as a result if the SQL query which gets a count of the rows containing the provided user name. By default, the Starter Site uses a column called Email in the UserProfile table for the storage of user names. This function is also called in a separate file named DupeCheck.cshtml. This file is placed in the root of the site:

@{
    Layout = null;
    if(IsAjax){
        var username = Request["username"];
        var result = Functions.IsDuplicate(username);
        Json.Write(new { isDupe = result }, Response.Output);
    }
}

DupeCheck.cshtml is designed to work exclusively with AJAX. The code includes an instruction to nullify any layout pages that might have been set in a _PageStart file, and then it uses the IsAjax property to determine if the page has been requested via an AJAX call. If it has, it uses the IsDuplicate method to check the availability of the posted username and returns the result to the calling code. The result is an anonymous type that has one propery: isDupe, which is a boolean. The anonymous type is serialised to JSON by the Json helper.

The final part of the solution is the dupecheck.js file. This uses jQuery:

$(function () {
    $('#email').change(function () {
        $.post(
            '/DupeCheck',
            { username: $(this).val() },
            function (data) {
                var emailValidation = $('span[data-valmsg-for="email"]');
                if (data.isDupe) {
                    if (emailValidation.hasClass('field-validation-valid')) {
                        emailValidation.removeClass('field-validation-valid');
                        emailValidation.addClass('field-validation-error');
                        emailValidation.text('That name is already taken!');
                    }
                } else {
                    if (emailValidation.hasClass('field-validation-error')) {
                        emailValidation.removeClass('field-validation-error');
                        emailValidation.addClass('field-validation-valid');
                        emailValidation.text('');
                    }
                }
            },'json'
        );
    });
});

An event handler is attached to the change event of the user name input (which has an id if email in the Starter Site). The current value is posted to the DupeCheck.cshtml page via AJAX. The code above checks the response from the server to see if the value is a duplicate, and if it is, an appropriate error message is displayed to the user.

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ASP.NET Hosting - ASPHostPortal.com :: Easy to Design Pie Chart and Donut Chart in ASP.NET

clock September 28, 2015 12:40 by author Kenny

Easy to Design Pie Chart and Donut Chart in ASP.NET

D3.js stands for Data-Driven Document. It is a JavaScript library using which we can manipulate documents based on data. The data can be fetched using multiple ways like Web Services, WCF Services, REST APIs or the relatively new Microsoft ASP.NET Web API amongst many others. Using D3, you can bind the data to the Document Object Model (DOM) and present that data with rich visualizations. D3 internally makes use of CSS, HTML and SVG capabilities to make your data presentable. It is powerful, fast and supports large datasets and dynamic behaviors for interactions and powerful and smooth animations.

D3.js provides easy and declarative selections of DOM nodes using W3C Selector APIs. D3 Selector APIs provides number of methods to manipulate nodes. For example –

  • Setting attributes and applying rich styles
  • Registering Event Listeners
  • You can add, remove and sort DOM nodes
  • You can change the HTML or the text contents of HTML elements
  • You can also have a direct selection/access to the DOM as each selection is an array of nodes

Likewise, we have various features of D3.js selectors which we can use to present data to our DOM nodes.

A simple selector example is the following:

var bodySelection = d3.select('body').style('background-color', 'blue');

In the above example, we are selecting body and changing its background color to blue. Another example would be as follows:

var divSelection = d3.selectAll('div').style('background-color', 'yellow');

In the above example, we are selecting all divs and changing its background color to yellow. If you are familiar with jQuery, the syntax looks similar to jQuery selectors or HTML5 Selectors.

D3 allows us to bind the data to the DOM elements and their attributes using a Data method which takes an array. For example:

d3.selectAll("div")
  .data([200,300,400,100])
  .style("height", function (data) { return data + "px"; });

In the above example, we are selecting all the div’s on the page and based on the index, the first value of an array will be passed to first div, second value to second div and so on.

In D3, you can also make use of Enter and Exit selector methods to create new nodes for incoming data, and remove outing nodes that are no longer used.

You can also apply transitions to nodes using D3. For example –

var area = d3.select('body')
            .append('svg')
            .attr('width', 500)
            .attr('height', 500);
 
var circle = area.append('rect')
                 .attr('width', 100)
                 .attr('height', 100)
                 .attr('fill', 'red');
 
circle.transition()
      .duration(2000)
      .delay(2000)
      .attr('width', 400)
      .each('start', function () {
            d3.select(this).attr('fill', 'green');})
      .transition()
      .duration(2000)
      .attr('height', 400)
      .transition()
      .duration(2000)
      .attr('width', 50)
      .transition()
      .duration(2000)
      .attr('height', 50)
      .each('end', function () {
            d3.select(this).attr('fill', 'blue'); });

In the above example, we are drawing a Rectangle and applying the transition to the same. Likewise, we can make use of various features of D3.js to present our data using rich visualizations.

A Quick overview of ASP.NET Web API

REST(REpresentational State Transfer) has emerged as the prominent way to create web services. By using REST we can build loose coupled services with data available on the web over HTTP protocol.

ASP.NET Web API is a platform for building RESTful applications. ASP.NET Web API is a framework using which we can build HTTP Services which can be called from a broad range of clients, browsers and mobile devices. ASP.NET Web API is the defacto standard of creating web services and replaces WCF.

When we think about exposing data on the web, we usually talk about four common operations which we use on a daily basis in our apps – CREATE, RETRIVE, UPDATE, DELETE.

We call these operations as CRUD operations. REST provides 4 basic HTTP verbs which we can map to our CRUD operations as described here - POST – CREATE, GET – RETRIVE, PUT – UPDATE, DELETE – DELETE.

By using REST, if you can connect to the web, any application can consume your data. When the data is pulled or pushed by using REST, the data is always serialized into or de-serialized from JSON or XML.

Setting up the application and ASP.NET Web API

To start designing the Pie chart and Donut chart, use the following tools and technologies:

  • Microsoft Visual Studio 2013 (Express or Professional)
  • Microsoft SQL Server 2012 (Express or Developer)
  • jQuery
  • D3.js
  • ASP.NET WEB API

Let’s first design the table where we can add our data. To design the table, open SQL Server Management Studio and write the following script:

CREATE TABLE [dbo].[CityPopulationTable](
    [CityID] [int] IDENTITY PRIMARY KEY,
    [CityName] [nvarchar](30) NULL,
    [Population] [int] NULL
)

Create an ASP.NET Web application by choosing Web Forms template. Then add the Entity Framework, jQuery and D3.js libraries into our web application using NuGet.

Once you add these libraries, right click on the Models folder in our Web application under Solution Explorer, and click on Add New Item. Choose Data  > ADO.NET Entity Data Model.

Using Entity Data Model Wizard, connect to our database and choose CityPopulationTable.

It’s time to implement the ASP.NET Web API into our project. Right click the web application and add a new folder with the name Controllers.

After adding the Web API, open Global.asax file and import two namespaces as shown here:

using System.Web.Http;
using System.Web.Routing;

Also add the following code to the Application_Start method –

GlobalConfiguration.Configure(WebApiConfig.Register);

The above line registers the Web API route in our web application. Now under App_Start folder, you will find WebApiConfig.cs file. Open this file and write the following code:

public static void Register(HttpConfiguration config)
{
    config.MapHttpAttributeRoutes();
 
    config.Routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{id}",
        defaults: new { id = RouteParameter.Optional }
    );
    var json = config.Formatters.JsonFormatter;
    json.SerializerSettings.PreserveReferencesHandling = Newtonsoft.Json.PreserveReferencesHandling.Objects;
    json.SerializerSettings.ContractResolver = new CamelCasePropertyNamesContractResolver();
    config.Formatters.Remove(config.Formatters.XmlFormatter);
}

In the above code, we are configuring Web API to make use of JSON formatter with camel casing, as most of the JavaScript developer will expect JSON output in Camel casing.

Now modify the Get method of our Web API controller as shown here:

public class PieChartController : ApiController
{
    NorthwindEntities dataContext = new NorthwindEntities();
    // GET api/piechart
    public IEnumerable<CityPopulationTable> Get()
    {
        return dataContext.CityPopulationTables.ToList();
    }
}

In the above code, we have created an object of our Entity Data model which will give access to the tables. Then we are returning an IEnumerable of our object CityPopulationTables.

Let us design our Pie chart and Donut chart using the Web API data shown in above:

Creating D3 Charts

Add a HTML page with the name ‘CityPolulationPieChart.html’. Once you add the page, we will reference the jQuery and D3.js file in the page:

<!DOCTYPE html>
<html lang="en">
<head>
    <title>Pie Chart Example</title>
    <script src="Scripts/jquery-1.10.2.js"></script>
    <script src="Scripts/d3.js"></script>
</head>

We will make use of jQuery AJAX function to fetch the data from our Web API and display it in a Pie and Donut chart. Let’s add a DOM ready function into our <body> tag. In this function, we will first declare two arrays. First array will hold the data for our chart and the second array will hold the colors which we will use for our chart:

$(function () {
            var chartData = [];
            var colors = [];
});

In the next step, we will fetch the data from our Web API using jQuery $.ajax function. Add this code after our array declaration:

$.ajax({
        type: "GET",
        url: "api/PieChart",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function (result) {
            $.each(result, function (i,j) {
                chartData.push(j.population);
                var currentColor = '#' + Math.floor(Math.random() * j.population+5566656).toString(16);
                colors.push(currentColor);
            });
            console.log(chartData);}
        error: function (msg) {
            $("#result").text(msg);
        }
});

Note: Although I have used success and error here for devs using an older version of jQuery, these methods have been deprecated from jQuery 1.8. You should replace them with .done() and fail().

In the above code, we are using a GET request with the Web API URL and the type of data set to JSON. On successful completion of the request, we are running a loop using $.each() which will push the fetched data into our chartData array. We are also generating colors and adding them into our colors array.

Now it’s time to use the D3 selector. We will use D3 selector to select the body and will append the SVG element to the same by setting its height and width. Add this code after console.log function. The code is shown below –

var radius = 300;
var colorScale = d3.scale.ordinal().range(colors);
                    
var area = d3.select('body').append('svg')
             .attr('width', 1500)
             .attr('height', 1500);

Also note that we are using the scale function of D3 which allows us to set the ordinal scale with the range to set the scale’s output range. We have also added a variable called radius which is set to 300.

The next step is to group the elements and draw an arc into our SVG as shown in the following code:

var pieGroup = area.append('g').attr('transform', 'translate(300, 300)');
var arc = d3.svg.arc()
                .innerRadius(0)
                .outerRadius(radius);

In the above code, we are using radius variable as the outer radius and fixing the inner radius to 0. As the next step, use a pie layout available under D3. Then pass the chart data and append it to our group ‘g’. The code is shown below –

var pie = d3.layout.pie()
       .value(function (data) { return data; })
var arcs = pieGroup.selectAll('.arc')
       .data(pie(chartData))
       .enter()
       .append('g')
       .attr('class', 'arc');

Also observe, we are using D3 selector to select arc class added at the end, which will select all the elements which has a class arc. In the last step,  append the path and fill the color from our array. We will also display the population data as text to our pie chart. The code is shown below –

arcs.append('path')
    .attr('d', arc)
    .attr('fill', function (d) { return colorScale(d.data); });
 
arcs.append('text')
    .attr('transform', function (data) { return 'translate(' + arc.centroid(data) + ')'; })
    .attr('text-anchor', 'middle')
    .attr('font-size', '1em')
    .text(function (data) { return data.data; });

Donut Chart

Designing a Donut chart is very simple. Just change the inner radius to something higher than zero. I am making it 200. The code is as shown here:

var arc = d3.svg.arc()
        .innerRadius(200)
        .outerRadius(radius);

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