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ASP.NET Core Hosting :: How to Add Custom Processing to Request in ASP.NET

clock January 22, 2019 08:57 by author Jervis

When a request comes in to your ASP.NET site, it's routed through a series of message handlers (in ASP.NET Web API) or modules (in ASP.NET MVC), each of which performs some operation on the request. After a request is processed (presumably, by one of your Controllers), the response from your request goes through those handlers or modules again on its way back to the client.

Putting code in a handler or module allows you to perform some operation on every inbound request or outbound response. So, for example, if you want to customize security for your site, a good way to do that is to add your own module or handler to this chain. Alternatively, if you wanted to check data leaving your Web API site for "sensitive" information, a module or handler would be a good choice for that task, also.

The Limitations of ASP.NET Modules

Of the two technologies, ASP.NET MVC's HttpModules are the most limited. In many ways, modules are legacy technology dating from the beginnings of ASP.NET. However, this is the only option if you really do want to process every request to your site (including, for example, requests for image files and CSS files). You can even use HttpModules in Web API application.

The problem here is that the methods in a module are passed an HttpApplication object that has Context, Request and Response properties. These properties give you access to information about the request being made to your site and the response your site is returning. These are the same objects you have access to in your Controllers and, as in your Controllers, most of the properties on these objects are read-only. So, in an HttpModule you're limited to reading the incoming request or response or adding/removing headers on them.

Creating an HttpModule

Creating a module is a bit of a pain, also. First, you need to declare a class that implements the IHttpModule interface and give it a property called ModuleName that returns the name of your class as a string. You'll also need a Dispose method. Here's the start of a typical module:

public class GenericHttpModule : IHttpModule
{
  public String ModuleName
  {
    get
    {
      return "GenericHttpModule";
    }
  }
  public void Dispose() { }

Your next step is to add the Init method, which returns nothing but accepts an HttpApplication object. In this method, to process incoming requests, you need to wire up a method of your own to the HttpApplication object's BeginRequest method; if you want to process the outbound Response, you'll wire up your method to the object's EndRequest method. Here's an Init method that does both:

public void Init(HttpApplication application)
{
  application.BeginRequest += (new EventHandler(Inbound));
  application.EndRequest += (new EventHandler(Outbound));
}

The signatures of both the BeginRequest and EndRequest methods are the same: The methods are passed two parameters, one of type object and one of type EventArgs. The first parameter is the interesting one because it holds a reference to the HttpApplication object that holds the Context, Request and Response properties. The two methods I would need to work with the code in my Init method would look like this:

private void Inbound(Object source, EventArgs e)
{
  HttpApplication application = (HttpApplication)source;
  // ... process inbound request ...
}
private void Outbound(Object source, EventArgs e)
{
  HttpApplication application = (HttpApplication)source;
  // ... process outbound request ...            
}

You have one final thing to do: To have ASP.NET actually use your module, you need to tell your application about it. You do that in your web.config file with an add element, inside its modules element (IIS 7.0) or its httpModules element (IIS 6.0/IIS 7.0 running in Classic mode). The add element must reference both the name of your class and its type. This element would tie my sample module into the chain in IIS 7.0 (and would do the same in the httpModules element):

<modules> <add name="GenericHttpModule" type="HttpModulesAPI.GenericHttpModule"/>

The Basics of Handlers

Creating an ASP.NET Web API handler is, comparatively speaking, much simpler.

First, you must create a class that inherits from DelegatingHandler. Once you've done that, you override your class's SendAsync method. When a request hits your site, your SendAsync method will be passed the incoming request as an HttpRequestMessage. You have more flexibility here than you do with modules: you can add or remove headers or replace the message's content.

When you've done whatever you want with the incoming request, you call the base class's SendAsync method, passing the request message (there's also a cancellation token involved but I'll ignore it for simplicity's sake). Calling the base SendAsync method passes the request on to the next handler in the chain and, eventually, to your controller.

After your Controller has processed your request, the response message will be returned back through the chain of handlers as an HttpResponseMessage object. That means that your call to the base SendAsync method will, eventually, return the response from your Controller to your handler. Again, you can add or remove headers or replace the message's Content before returning the message to the ASP.NET process that called your delegating handler in the first place. Eventually, that response message will be delivered to the client that made the original request.

Here's the skeleton of a typical handler:

public class GenericMessageHandler : DelegatingHandler
{
  protected async override System.Threading.Tasks.Task<HttpResponseMessage>
          SendAsync(HttpRequestMessage request,
          System.Threading.CancellationToken cancellationToken)
  {
    //...work with HttpRequestMessage...
    HttpResponseMessage resp = await base.SendAsync(request, cancellationToken);
    //...work with HttpReqponseMessage
    return resp;
  }
}

And, in fact, you don't have to call the base SendAsync method at all -- there's nothing stopping you from creating an HttpResponseMessage in your SendAsync method and returning that.

Adding Your Handler to the Pipeline

To have your application use your handler, go to your App_Start folder, open the WebApiConfig file and add your new handler class to the config parameter's MessageHandlers class. This code, for example, adds my handler to the pipeline:

config.MessageHandlers.Add(new GenericMessageHandler());

But I have to be honest here: My experience has been that (outside of security) there are very few operations that I want to perform on every request to my ASP.NET Web API site. As a result, my typical handler begins with a bunch of If statements that check to see if this is a request that my handler should work with. In those scenarios, ASP.NET Web API gives me alternative: I can add the relevant handler just to the specific routes where it's needed.

To do that, I go to ASP.NET Web API's WebApiConfig file in the App_Start folder and add a fifth parameter to the MapHttpRoute method used to define routes (to use this parameter, you must provide a value for the constraints parameter on the method, even if all you provide is null). The handler parameter allows me to specify a DelegatingHandler to be used in processing requests and responses in that route. Here's an example with my GenericMessageHandler added to a route that grabs requests for my Customer controller (as this code shows, to tie my handler into the processing pipeline I also have to set its InnerHandler property to HttpControllerDispatcher):

config.Routes.MapHttpRoute(
                name: "CustomerApi",
                routeTemplate: "api/Customer/{id}",
                defaults: new { id = RouteParameter.Optional },
                constraints: null,                            
                handler: new GenericMessageHandler(){InnerHandler = new HttpControllerDispatcher(config) }
            );

I can, of course, selectively add this handler to multiple routes.

So if you want to add processing to every request that your site gets (or even just some of them), then you don't have to add code to every Controller or Action method in your project. You can, instead, bundle that code into either a module (for ASP.NET MVC) or a handler (for ASP.NET Web API).



ASP.NET Hosting :: Alternative Localization for Asp.Net Core Applications

clock January 16, 2019 10:41 by author Jervis

Asp.Net Core Built-In Support

This is code fragment from official documentation how to localize content using built-in functionality.

App Content Localization

[Route("api/[controller]")]
public class AboutController : Controller
{
    private readonly IStringLocalizer<AboutController> _localizer;

    public AboutController(IStringLocalizer<AboutController> localizer)
    {
        _localizer = localizer;
    }

    [HttpGet]
    public string Get()
    {
        return _localizer["About Title"];
    }
}

And if you are working with Html content that shouldn't be escaped during rendering - you are using IHtmlLocalizerimplementation that returns LocalizedHtmlString instance.

public class BookController : Controller
{
    private readonly IHtmlLocalizer<BookController> _localizer;

    public BookController(IHtmlLocalizer<BookController> localizer)
    {
        _localizer = localizer;
    }

    public IActionResult Hello(string name)
    {
        ViewData["Message"] = _localizer["<b>Hello</b><i> {0}</i>", name];

        return View();
    }
}

View Localization

For the view localization - there is another injectable interface IViewLocalizer.

@inject IViewLocalizer Localizer

@{
    ViewData["Title"] = Localizer["About"];
}

Alternative: Strongly-Typed DbLocalizationProvider

Where is my problem with built-in providers? They all are "stringly-typed". You have to provide string as either key or translation of the resource. I'm somehow more confident strongly-typed approach where I can use "Find All Usages", "Rename" or do any other static code operation that's would not be entirely possible in built-in approach.

Over the time I've been busy developing alternative localization provider for Asp.Net and Episerver (it's brilliant content management system) platforms specifically.

Thought getting that over to Asp.Net Core should not be hard. And it wasn't. So here we are - DbLocalizationProviderfor Asp.Net Core.

Getting Started

There are couple of things to setup first, before you will be able to start using strongly-typed localization provider.

First, you need to install the package (it will pull down other dependencies also).

PM> Install-Package LocalizationProvider.AspNetCore

Second you need to setup/configure services.
In your Startup.cs class you need to stuff related to Mvc localization (to get required services into DI container - service collection).

And then services.AddDbLocalizationProvider(). You can pass in configuration settings class and setup provider's behavior.

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        services.AddLocalization();

        services.AddMvc()
                .AddViewLocalization()
                .AddDataAnnotationsLocalization();

        services.AddDbLocalizationProvider(cfg =>
        {
            cfg...
        });
    }
}

After then you will need to make sure that you start using the provider:

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public void ConfigureServices(IServiceCollection services)
    {
        ...
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        ...

        app.UseDbLocalizationProvider();
    }
}

Using localization provider will make sure that resources are discovered and registered in the database (if this process will not be disabled via AddDbLocalizationProvider() method).

App Content Localization

Localizing application content via IStringLocalizer<T> is similar as that would be done for regular Asp.Net applications.

You have to define resource container type:

[LocalizedResource]
public class SampleResources
{
    public string PageHeader => "This is page header";
}

Then you can demand IStringLocalizer<T> is any place you need that one (f.ex. in controller):

public class HomeController : Controller
{
    private readonly IStringLocalizer<SampleResources> _localizer;

    public HomeController(IStringLocalizer<SampleResources> localizer)
    {
        _localizer = localizer;
    }

    public IActionResult Index()
    {
        var smth = _localizer.GetString(r => r.PageHeader);
        return View();
    }
}

As you can see - you are able to use nice strongly-typed access to the resource type: _localizer.GetString(r => r.PageHeader);.

Even if you demanded strongly-typed localizer with specified container type T, it's possible to use also general/shared static resources:

[LocalizedResource]
public class SampleResources
{
    public static string SomeCommonText => "Hello World!";
    public string PageHeader => "This is page header";
}

public class HomeController : Controller
{
    private readonly IStringLocalizer<SampleResources> _localizer;

    public HomeController(IStringLocalizer<SampleResources> localizer)
    {
        _localizer = localizer;
    }

    public IActionResult Index()
    {
        var smth = _localizer.GetString(() => SampleResources.SomeCommonText);
        return View();
    }
}

View Localization

Regarding the views, story here is exactly the same - all built-in approach is supported:

@model UserViewModel
@inject IViewLocalizer Localizer
@inject IHtmlLocalizer<SampleResources> HtmlLocalizer

@Localizer.GetString(() => SampleResources.SomeCommonText)
@HtmlLocalizer.GetString(r => r.PageHeader)

Data Annotations

Supported. Sample:

[LocalizedModel]
public class UserViewModel
{
    [Display(Name = "User name:")]
    [Required(ErrorMessage = "Name of the user is required!")]
    public string UserName { get; set; }

    [Display(Name = "Password:")]
    [Required(ErrorMessage = "Password is kinda required :)")]
    public string Password { get; set; }
}

View.cshtml:

@model UserViewModel

<form asp-controller="Home" asp-action="Index" method="post">
    <div>
        <label asp-for="UserName"></label>
        <input asp-for="UserName"/>
        <span asp-validation-for="UserName"></span>
    </div>
    <div>
        <label asp-for="Password"></label>
        <input asp-for="Password" type="password"/>
        <span asp-validation-for="Password"></span>
    </div>
    ...
</form>

Localization in Libraries

You can either rely on IStringLocalizer implementation that's coming from Microsoft.Extensions.Localizationnamespace and demand that one in your injections:

using Microsoft.Extensions.Localization;
public class MyService
{
    public MyService(IStringLocalizer localizer)
    {
       ...
    }
}

Or you can also depend on LocalizationProvider class defined in DbLocalizationProvider namespace:

using DbLocalizationProvider;
public class MyService
{
    public MyService(LocalizationProvider provider)
    {
       ...
    }
}

Both of these types provide similar functionality in terms how to retrieve localized content.

Changing Culture

Sometimes you need to get translation for other language and not primary UI one.
This is possible either via built-in method:

@inject IHtmlLocalizer<SampleResources> Localizer

Localizer.WithCulture(new CultureInfo("no"))
         .GetString(() => SampleResources.SomeCommonText)

Or via additional extension method:

@inject IHtmlLocalizer<SampleResources> Localizer
Localizer.GetStringByCulture(() => SampleResources.SomeCommonText, new Culture("no"))

Stringly-Typed Localization

For backward compatibility or even if you wanna go hardcore and supply resource keys manually (for reasons) stingly-typed interface is also supported:

using Microsoft.Extensions.Localization;

public class MyService
{
    public MyService(IStringLocalizer localizer)
    {
       var header = localizer["MyProject.Resources.Header"];
    }
}

 



ASP.NET Core Hosting :: 5 Reasons to Use ASP.NET Core

clock January 9, 2019 08:33 by author Jervis

When it comes to web application development, there are multiple technologies available to choose from. There are open-source technologies like Java & PHP, and then, there is closed-source technology ASP.NET MVC.

While millions of web developers use ASP.NET MVC to build web applications, but the latest ASP.NET Core framework offers far more benefits than the ASP.NET MVC for web application development.

ASP.NET Core is an open-source, cross-platform framework developed by both the Microsoft and its community. Basically, it is a complete reform of ASP.NET that combines MVC structure and Web API into a single framework.

Why Use ASP.NET Core for Web Application Development?

ASP.NET Core is an emerging, robust, and feature-rich framework that provides features to develop super-fast APIs for web apps.

Let’s take a look at the elements that make ASP.NET Core a right choice for Enterprise app development

1 — The MVC Architecture

Back in the days of the classic ASP.NET, developers had to worry about IsPostBack & ViewState. But with MVC, web application development has become more natural and the workflow also more efficient. In addition, the latest ASP.NET Core framework further helps in developing web APIs & web applications testable in better way, by achieving a clear separation of concerns.

In simple terms, ASP.NET Core makes it easier for developers to code, compile, and test something in either model, view, or the controller.

2 — Razor Pages

Razor Pages is a new element of ASP.NET Core that makes programming page-focused scenarios more productive. In technical terms, Razor Pages is a page-based coding model that makes building web UI easier.

If you’ve ever worked on ASP.NET MVC framework before, then you already know that the controller classes are filled with a large amount of actions. And not only that, but they also grow as the new things are added.

With Razor Pages, each web page becomes self-contained with its View component, and the code is also organized well together.

3 — Provides Support for Popular JavaScript Frameworks

Unlike ASP.NET MVC, the new .NET Core framework provides build-in templates for two most popular JavaScript frameworks — Angular & React (plus Aurelia).

The JavaScriptServices in the new ASP.NET Core provides an infrastructure that developers need to develop client-side apps using the above mentioned JavaScript frameworks.

The JavaScriptServices basically aims to eliminate underlying plumbing to allow developers start coding applications sooner, making it possible to build feature-rich front-end web applications.

4 — Improved Collaboration & Cross-Platform Support

ASP.NET Core is a cross-platform framework, meaning the apps build using this framework can run on Windows, Linux, and Mac Operating systems. In addition, the developers are also free to choose their development OS as well.

In simple terms, your developers can work across Linux, MacOS, or Windows and they can still collaborate on the same project. This is possible with unified experience offered by the Visual Studio IDE.

In short, the ASP.NET Core framework has the capacity to build & run web applications on Windows, Linux, and Mac OS.

5 — In-Built Dependency Injection Support

ASP.NET Core framework provides an in-built dependency injection, meaning you do not need rely on third-party frameworks like Ninject or AutoFactor anymore.

Dependency Injection is basically a pattern that can help developer distinguish the different pieces of their apps. Before the release of ASP.NET Core, the only way to get Dependency injection in any application was by using the above mentioned frameworks (Ninject, AutoFactor). But in ASP.NET Core, the dependency injection is treated as a first-class citizen. What this means is that developers are no longer limited to web applications, and they can leverage new libraries in more event-driven apps such as AWS Lambda or Azure Functions.

Overall, the dependency injection in the ASP.NET Core framework improves the testability and extensibility of web applications. 



ASP.NET Core Hosting :: Differences Between Kestrel and IIS Features

clock December 21, 2018 08:47 by author Jervis

The Kestrel web server is a new web server as part of ASP.NET Core. It is now the preferred web server for all new ASP.NET applications. In this article, we will review what it is, how to use it, and the differences between Kestrel vs IIS.

Why Do We Need the New Kestrel Web Server? What about IIS?

If you have been developing ASP.NET applications for a while, you are probably familiar with Internet Information Services (IIS). It does literally anything and everything as a web server. It is infinitely configurable with ASP.NET handlers & modules via the ASP.NET integrated pipeline. It has robust management APIs for configuration and deployment. It is even an FTP server.

The same codebase that has to support the original “.asp” pages from 15+ years ago now also handles new technologies like async ASP.NET. Like most software, as it ages it gets modified over time, they carry a lot of weight and bloat. IIS does everything, but it is not the fastest web server around. Lightweight web servers like Node.js and Netty make IIS look old and slow.

A Chance to Start Over

By creating the Kestrel web server, the .NET community was able to start over from scratch. They no longer had to worry about backward compatibility for technologies that were 15+ years old. They could take all of their past knowledge to build the simplest and fastest web server possible. That is exactly what they did. Kestrel and ASP.NET Core were built for speed.

Kestrel is more than just a new web server. ASP.NET Core & Kestrel combined are a whole new request pipeline for how ASP.NET requests work. Things like HTTP modules & handlers have been replaced with simple middleware. The entire System.Web namespace is gone. Another big advantage is designing a web server to take advantage of async from the ground up. Performance is now a feature of ASP.NET.

Built for Speed

One of the big problems with IIS and the existing ASP.NET pipeline was the performance of it. For most real world applications, the performance is perfectly fine. However, it lagged way behind in benchmarks. The combination of Kestrel & ASP.NET Core has been shown to be many times faster. It is great to see the team putting performance as a top priority.

Granted, benchmarking an ASP.NET request that says “hello world” is not comparable to most real applications that do multiple SQL queries, cache calls, and web service calls in a single request. ASP.NET makes it easy to do most I/O operations asynchronously. ASP.NET Core & Kestrel have been designed from the ground up to take advantage of async. Most real world apps should perform better if the developers follow good best practices around using async.

Cross Platform

If the goal was to get ASP.NET running on Linux, that meant porting IIS to Linux or making ASP.NET work without IIS. Kestrel solved this problem. As a developer, I can write my ASP.NET application and deploy it to Windows or Linux either one. Kestrel works as my web server on both. However, it is still recommended to use IIS, Apache, or NGINX as a reverse proxy in front of it. Next, we will discuss why that is.

Comparing Kestrel Web Server vs IIS

IIS does almost everything. Kestrel does as little as possible. Because of this, Kestrel is much faster but also lacks a lot of functionality. I would think of Kestrel as really more of an application server. It is recommended to use another web server in front of it for public web applications. Kestrel is designed to run ASP.NET as fast as possible. It relies on a full fledged web server to do deal with things like security, management, etc.

Feature Comparison for Kestrel vs IIS

Here is an IIS vs Kestrel comparison of some key features. This should help you better understand the limitations of Kestrel. You can overcome these limitations by pairing it up with IIS or NGINX.



ASP.NET Hosting :: How to Setup URL Redirection

clock November 15, 2018 07:07 by author Jervis

We have so many clients asking about this issue. So, we decide to write this tutorial and hope this information can help other people too. In this review, we will write simple tutorial about how to setup http/https redirection in IIS.

There are lots of routing options accessible in ASP.NET but still it comes a time when you need to manipulate a URL and manipulating it outside a code comes handy. When this happens, the best you can do id to use IIS Rewrite Module. Transforming various URL’s out of code enables you to do various things including performing redirections for archive or transferred content without interfering with the code, you can easily implement SEO optimizations and tweaks quickly and easily without code and many more. Below is a collection of useful IIS rewrite rules that will help you understand IIS rewrites.

Useful IIS Rewrite Rules

Adding www Prefix

This is a basic rule that adds prefix “www” to any URL you need. This is a requirement for SEO.

Redirection from Domain 1 to Domain 2

This rule comes handy when you change the name of your site or may be when you need to catch and alias and direct it to your main site. If the new and the old URLs share some elements, then you could just use this rule to have the matching pattern together with the redirect target being.

HTTPS/HTTP Redirection

Redirecting users from HTTP to HTTPS is one of the reasons that you need to apply useful IIS rewrite rules. It can lead to conditional statements while looking for dev/test mode in your code. This rules allows you to handle the redirection without much statements which is tidier.

There is a pair of rules in this case each for one of the two ways. In both the rules, a check is performed to verify that the protocol used is http/https. The rules work on the same URL patterns or the similar lists of pages to match. For the redirect to HTTP, it is not about matching the pages; it is a reverse of the first rule and usually have a number of .NET/site paths that are excluded.

Setup Redirection Using IIS

Above steps is to setup URL redirection via your code. But, if you manage your own server, you can also setup redirection via IIS. The following is the steps

1. Download and install the “URL Rewrite” module.

2. Open the “IIS Manager” console and select the website you would like to apply the redirection to in the left-side menu:



3. Double-click on the “URL Rewrite” icon.

4. Click “Add Rule(s)” in the right-side menu.

5. Select “Blank Rule” in the “Inbound” section, then press “OK”:

6. Enter any rule name you wish.

7. In the “Match URL” section:

- Select “Matches the Pattern” in the “Requested URL” drop-down menu 
- Select “Regular Expressions” in the “Using” drop-down menu 
- Enter the following pattern in the “Match URL” section: “(.*)” 
- Check the “Ignore case” box

 

 

8. In the “Conditions” section, select “Match all” under the “Logical Grouping” drop-down menu and press “Add”.

9. In the prompted window:

- Enter “{HTTPS}” as a condition input 
- Select “Matches the Pattern” from the drop-down menu 
- Enter “^OFF$” as a pattern 
- Press “OK”

10. In the “Action” section, select “Redirect” as the action type and specify the following for “Redirect URL”:

https://{HTTP_HOST}/{R:1}

11. Check the “Append query string” box.

12.Select the Redirection Type of your choice. The whole “Action” section should look like this:

 

NOTE: There are 4 redirect types of the redirect rule that can be selected in that menu: 

- Permanent (301) – preferable type in this case, which tells clients that the content of the site is permanently moved to the HTTPS version. Good for SEO, as it brings all the traffic to your HTTPS website making a positive effect on its ranking in search engines. 
- Found (302) – should be used only if you moved the content of certain pages to a new place *temporarily*. This way the SEO traffic goes in favour of the previous content’s location. This option is generally not recommended for a HTTP/HTTPS redirect. 
- See Other (303) – specific redirect type for GET requests. Not recommended for HTTP/HTTPS. 
- Temporary (307) – HTTP/1.1 successor of 302 redirect type. Not recommended for HTTP/HTTPS.

13. Click on “Apply” on the right side of the “Actions” menu.

The redirect can be checked by accessing your site via http:// specified in the URL. To make sure that your browser displays not the cached version of your site, you can use anonymous mode of the browser.

The rule is created in IIS, but the site is still not redirected to https://

Normally, the redirection rule gets written into the web.config file located in the document root directory of your website. If the redirection does not work for some reason, make sure that web.config exists and check if it contains the appropriate rule.

To do this, follow these steps:

1. In the sites list of IIS, right-click on your site. Choose the “Explore” option:

 

2. “Explore” will open the document root directory of the site. Check if the web.config file is there.

3. The web.config file must have the following code block:

<configuration> 
<system.webServer> 
<rewrite> 
<rules> 
<rule name="HTTPS force" enabled="true" stopProcessing="true"> 
<match url="(.*)" /> 
<conditions> 
<add input="{HTTPS}" pattern="^OFF$" /> 
</conditions> 
<action type="Redirect" url="https://{HTTP_HOST}/{R:1}" redirectType="Permanent" /> 
</rule> 
</rules> 
</rewrite> 
</system.webServer> 
</configuration>

4. If the web.config file is missing, you can create a new .txt file, put the aforementioned code there, save and then rename the file to web.config.

 

 



ASP.NET Hosting - ASPHostPortal.com :: JavaScript style setTimeout and setInterval in C#

clock January 31, 2017 05:05 by author Armend

I found JavaScript setTimeout and setInterval functions quite handy for timer like functionality and some time wish I could use that in C# too. In an earlier post I create a C# like timer functionality in JavaScript. Now, I want to do opposite i.e. implement JavaScript setTimeout and setInterval like functionality in C#.
This is can be done very easily using Lamda expressions and Timer. Look at the below utility class -

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace DailyCoding.EasyTimer
{
    public static class EasyTimer
    {
        public static IDisposable SetInterval(Action method, int delayInMilliseconds)
        {
            System.Timers.Timer timer = new System.Timers.Timer(delayInMilliseconds);
            timer.Elapsed += (source, e) =>
            {
                method();
            };

            timer.Enabled = true;
            timer.Start();

            // Returns a stop handle which can be used for stopping
            // the timer, if required
            return timer as IDisposable;
        }

        public static IDisposable SetTimeout(Action method, int delayInMilliseconds)
        {
            System.Timers.Timer timer = new System.Timers.Timer(delayInMilliseconds);
            timer.Elapsed += (source, e) =>
            {
                method();
            };

            timer.AutoReset = false;
            timer.Enabled = true;
            timer.Start();

            // Returns a stop handle which can be used for stopping
            // the timer, if required
            return timer as IDisposable;
        }
    }
}

To use setTimeout this you can simply do -

EasyTimer.SetTimeout(() =>
{
    // --- You code here ---
    // This piece of code will once after 1000 ms delay

}, 1000);

The code will run after 1000 ms delay similarly like JavaScript setTimeout. The function also returns a handle. If you want clearTimeout like functionality, then the simply dispose off the handle.

var stopHandle = EasyTimer.SetTimeout(() =>
{
    // --- You code here ---
    // This piece of code will once after 1000 ms

}, 1000);


// In case you want to clear the timeout

stopHandle.Dispose();
Similarly you can use setInterval as -
EasyTimer.SetInterval(() =>
{
    // --- You code here ---
    // This piece of code will run after every 1000 ms

}, 1000);

and SetInterval also returns a stop handle which you can use for clearInterval like functionality. Just dispose off the handle -

var stopHandle = EasyTimer.SetInterval(() =>
    {
        // --- You code here ---
        // This piece of code will run after every 1000 ms
        // To stop the timer, just dispose off the stop handle

    }, 1000);


// In case you want to clear the interval
stopHandle.Dispose();

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ASP.NET Hosting - ASPHostPortal.com :: Simple Steps to Render ASP.NET MVC Layout

clock January 27, 2017 06:56 by author Dan

According to dotnettrick website. In Asp.Net MVC, Layouts are like as Master Pages in Asp.Net Web Forms. These helps us to maintain consistent look and feel across all the views within your Asp.Net MVC application. Like Master Pages, Layout may contains common CSS, jQuery files across the multiple Views and one or more placeholders for which Views provide content. For layout and its components refer this article Layouts, RenderBody, RenderSection and RenderPage in ASP.NET MVC.

In Asp.Net MVC, at application level we have _ViewStart file with in Views folder for defining the default Layout page for your Asp.Net MVC application. In this article, I am going to expose the different ways to apply layout pages for your application. Suppose we have to render the layouts as shown in the fig. by using various ways.

Method 1 : Control Layouts rendering by using _ViewStart file in the root directory of the Views folder

We can change the default rendering of layouts with in _ViewStart file by using the below code:

    @{
     var controller = HttpContext.Current.Request.RequestContext.RouteData.Values["Controller"].ToString();
    
     string layout = "";
     if (controller == "Admin")
     {
     layout = "~/Views/Shared/_AdminLayout.cshtml";
     }
     else
     {
     layout = "~/Views/Shared/_Layout.cshtml";
     }
    
     Layout = layout;
    }

Method 2 : Return Layout from ActionResult

We can also override the default layout rendering by returning the layout from the ActionResult by using the below code:

    public ActionResult Index()
    {
     RegisterModel model = new RegisterModel();
     //TO DO:
     return View("Index", "_AdminLayout", model);
    }

Method 3 : Define Layout with in each view on the top

We can also override the default layout rendering by defining the layout on the view by using the below code:

    @{
     Layout = "~/Views/Shared/_AdminLayout.cshtml";
    }

Method 4 : Adding _ViewStart file in each of the directories

We can also set the default layout for a particular directory by putting _ViewStart file in each of the directories with the required Layout information as shown below:


    @{
     Layout = "~/Views/Shared/_AdminLayout.cshtml";
    }

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ASP.NET Hosting - ASPHostPortal.com :: Dynamically from code behind in asp.net using C#

clock January 24, 2017 11:50 by author Armend

In this example we explain that how to change CSS dynamically from code behind in asp.net using C#. or how to change CSS file programmatically in C# code(back end  code) in asp.net. Some time we have requirement like if user click on or check Lightweight button then Lightweight CSS is apply to the application for these user only same like if user checked or click on Professional button then Professional look is applied to the application for these user only these totally is dynamic and depend on user requirement.


So how to change or switch CSS file dynamically from code behind in asp.net using C#.

ChangeCSSFileDynamically.aspx:


<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="ChangeCSSFileDynamically.aspx.cs"
Inherits="WebApplication1.ChangeCSSFileDynamically" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
    <title>Dynamically change (switch) CSS file programmatically from code behind in ASP.Net</title>
    <link id="lnkCSS" runat="server" href="~/CSS/Lightweight.css" rel="stylesheet" type="text/css" />
</head>
<body>
    <form id="form1" runat="server">
    <asp:Label ID="Label1" runat="server" Text="This is a Label" CssClass="label"></asp:Label>
    <hr />
    <asp:RadioButton ID="chkLightWeight" runat="server" GroupName="CSSTheme" AutoPostBack="true" Text="LightWeight"
        OnCheckedChanged="chkLightWeight_CheckedChanged1" />
    <asp:RadioButton ID="chkProfessional" runat="server" GroupName="CSSTheme" AutoPostBack="true" Text="Professional"
        OnCheckedChanged="chkProfessional_CheckedChanged1" />
    </form>
</body>
</html>

ChangeCSSFileDynamically.aspx.cs:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

namespace WebApplication1
{
    public partial class ChangeCSSFileDynamically : System.Web.UI.Page
    {

        protected void chkLightWeight_CheckedChanged1(object sender, EventArgs e)
        {
            lnkCSS.Attributes["href"] = "~/CSS/Lightweight.css";
        }

        protected void chkProfessional_CheckedChanged1(object sender, EventArgs e)
        {
            lnkCSS.Attributes["href"] = "~/CSS/Professional.css";
        }
    }
}

Lightweight.css:

body
{
    font-family:Times New Roman;
    font-size:10pt;
}
.label
{
    font-weight:bold;
    color:Purple;
}

Professional.css:

body
{
    font-family:Arial;
    font-size:bold;
}
.label
{
    font-weight:bold;
    color:yellow;
}

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ASP.NET Hosting -ASPHostPortal.con :: How to Use Complex Number in ASP.NET

clock January 22, 2017 18:47 by author Dan

According to dailydotnettips website. Complex numbers are not new to numeral system. A complex number contains one real part and another imaginary part. We can easily implement such a Type, but with .NET 4.0 System.Numerics.dll contains a new Type (struct) called Complex which deals with Complex numbers .

You can represent a number in Complex form very easily using Complex type.
Lets see how :
   
Complex c = new Complex(4.4, 3.1);
Console.WriteLine(c);


You can even specify like this :
   
Complex c = 35.302;
Console.WriteLine(c);


Or like this :
   
Complex c = (Complex)35.302m;
Console.WriteLine(c);


So everything is taken care automatically. You can also use FromPolarCoordinates to take a complex number from its polar co-ordinates.
   
Complex c = Complex.FromPolarCoordinates(39.454834, 2.548454);
Console.WriteLine(c);


You can get each component of a Complex number using properties associated with it.

Real : Represents the Real part of the Number.
Imaginary : Represents the Imaginary part of the number.
Magintude : Gets the absolute value of the Complex number
Phase : Gets the phase of the complex number.

The complex number also exposes some of the important methods :

Conjugate
Log
Reciprocal
Sqrt (Square Root) etc.


For more information about Complex numbers please refer ComplexNumber
Hope you like this post.
Happy Coding.

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ASP.NET Hosting - ASPHostPortal.com :: How to Set Enter Shortcut to Submit Form in ASP.NET

clock January 20, 2017 07:04 by author Dan

According to dotnettrick website. Suppose, you want to press/click submit button on Enter key press or you are trying to post the form on Enter key press. In asp.net, to achieve this functionality we need to set "Defaultbutton" property either in Form or in panel.

Form DefaultButton Property

     <form id="form1" runat="server" defaultbutton="btnSubmit">
   <div>
    <asp:TextBox ID="txtUserID" runat="server"/> <asp:TextBox ID="txtUserpwd" runat="server"/> <asp:Button ID="btnSubmit" runat="server" OnClick="btnSubmit _Click" Text="Submit"/>
   </div>
   </form>

Panel DefaultButton Property

     <asp:Panel ID="Panel1" runat="server" defaultbutton="btnSubmit">
    <div>
    <asp:TextBox ID="txtUserID" runat="server"/> <asp:TextBox ID="txtUserpwd" runat="server"/> <asp:Button ID="btnSubmit" runat="server" OnClick="btnSubmit _Click" Text="Submit"/>
    </div>
   </asp:Panel >

Note

  • We specify the defaultbutton property at the Form level in the form tag when there is only one Submit Button for post back.
  • We specify the defaultbutton property at the Panel level in the Panel tag when there are multiple Submit Button for post back.

Summary

In this article I try to explain the default submit behavior of form and panel. I hope you will refer this article for your need. I would like to have feedback from my blog readers. Please post your feedback, question, or comments about this article.

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