How to handle unknown actions in ASP.NET Core 5 MVC
ASP.NET 5 is an open rise web application outgrowth framework for edifice present web applications. It is built on the .NET Core runtime and you can take gain of it to build and run applications on Windows_ Linux_ and the Mac. ASP.NET Core MVC is a lightweight_ open rise_ greatly testable framework built on top of the ASP.NET Core runtime and is useful as part of ASP.NET 5.
When working in ASP.NET Core MVC_ you might frequently need to feel actions that are not known at outgrowth time. This article talks almost how you can feel mysterious action orders in ASP.NET Core 5. The code samples are given in C#.
To work with the code samples granted in this article_ you should have Visual Studio 2019 installed in your order. If you dont already have a copy_ you can download Visual Studio 2019 here . And you can download .NET 5.0 here .
Create an ASP.NET Core 5 MVC project in Visual Studio 2019 First off_ lets form an ASP.NET Core project in Visual Studio 2019. Following these steps should form a new ASP.NET Core 5 project in Visual Studio 2019.
Launch the Visual Studio IDE.<_li>
Click on “Create new project.”<_li>
In the “Create new project” window_ select “ASP.NET Core Web App Model-View-Controller” from the list of templates displayed.<_li>
Click Next.<_li>
In the “Conaspect your new project” window_ particularize the name and location for the new project.<_li>
Optionally check the “Place solution and project in the same directory” check box_ depending on your prelations.<_li>
Click Next.<_li>
In the “Additional Information” window shown next_ select .NET 5.0 as the target framework from the drop-down list at the top. Leave the “Authentication Type” as None lapse.<_li>
Ensure that the check boxes “Enable Docker”_ “Conaspect for HTTPS” and “Enable Razor runtime collation” are unchecked as we wont be using any of those components here.<_li>
Ensure that Authentication is set to “None” as we wont be using authentication whichever.<_li>
Click Create.<_li>
<_ol>A new ASP.NET Core MVC project will be formd. Well use this project in the posterior sections in this article.
Create a controller in ASP.NET Core 5 MVC If you look in the Solution Explorer window_ youll see that a controller class named HomeController was formd by lapse. Lets form our own controller class_ AuthorController_ which well use throughout this article. To do this_ pursue the steps outlined under:
<_aside>
Right-click on the Controllers solution folder of your project in the Solution Explorer window. Select “Add -gt; Controller...”<_li>
In the “Add New Scaffolded Item” window_ select the “MVC Controller with read_write actions” project template and click Add.<_li>
Specify a name for your new controller class well use AuthorController here and click Add.<_li>
<_ol>Replace the lapse code of the AuthorController with the pursueing code:
open class AuthorController : Controller { [HttpGet] open ActionResult Index { recur View; } }<_pre>In ASP.NET Core MVC_ a controller is a class that is typically named with the suffix “Controller” and is used to mark and logically cluster a assembly of correspondent actions. Whenever you form a new controller_ a lapse action order named Index is formd automatically.
<_aside>The lapse action order in ASP.NET Core MVC Note that the name of the lapse action order_ Index_ is specified in the Conaspect order of the Startup class as shown in the code snippet given under.
app.UseEndpointsendpoints _gt;{ endpoints.MapControllerRoute name: "lapse"_ model: "{controller_Home}_{action_Index}_{id?}";};<_pre>Because the action name has been specified as Index in the precedent code snippet_ you must have a file named Index.cshtml in the Views_Author folder of your project. You can now run the application and browse whichever of the pursueing endpoints:
http:__localhost:51913_Author http:__localhost:51913_Author_Index
Youll remark that the Index page will be displayed in both cases.
<_aside>The problem with mysterious action orders Lets now apprehend the problem well explain in this sample. When working with ASP.NET Core MVC you will frequently need action orders that are not known at the time of outgrowth of the application.
Suppose you are edifice a searchable directory of openations_ and you want users to be able to search by creator name_ or by book or article title. You would need to know the details of all the creators_ books_ and articles the directory will hold i.e._ creator names_ book titles_ article titles_ openation dates_ and so on in advance. How do you execute that?
To execute this_ you would need to have the corresponding views i.e._ Authors.cshtml_ Books.cshtml_ Articles.cshtml_ etc. in the Views folder as well as action orders that can be invoked using URLs such as the pursueing:
_Author_Books _Author_Articles
Consider the pursueing URL_ which easily maps to the corresponding action order_ namely the Index order of the AuthorController.
_Author_Index
However_ if you try to browse whichever of the pursueing endpoints_ youll take an fault from the web browser owing the corresponding action orders or views are not useful.
_Author_Books_Author_Articles
Use endpoint routing to feel mysterious actions We can explain this problem using routing — by creating a way that dynamically maps to an action that accepts a view name as a parameter and renders the view if a view with the specified name is establish.
In the Startup.cs file_ form a new way determination in the Conaspect order as shown in the code snippet given under.
endpoints.MapControllerRoute name: "viewName"_ model: "{controller}_{*viewName}"_ lapses: new { action _ "DisplayAnyView" };<_pre>The DisplayAnyView order looks like this:
open IActionResult DisplayAnyViewstring viewName{ recur ViewviewName;}<_pre>The AuthorController now looks like this:
open class AuthorController : Controller { [HttpGet] open ActionResult Index { recur View; } open IActionResult DisplayAnyViewstring viewName { recur ViewviewName; } }<_pre>When you execute the application now_ youll remark that the fracture point is hit successfully as shown in the aspect under.
IDG<_little><_aspect>Use attribute routing to feel mysterious actions You can also explain the problem using attribute routing as shown in the code snippet given under.
[HttpGet"DisplayAnyView"]open IActionResult DisplayAnyViewstring viewName{ recur ViewviewName;}<_pre>Here is the complete code listing of the AuthorController class for your relation.
[Route"[controller]"] open class AuthorController : Controller { [Route"[action]"] [HttpGet] open ActionResult Index { recur View; } [HttpGet"DisplayAnyView"] open IActionResult DisplayAnyViewstring viewName { recur ViewviewName; } }<_pre>Lastly_ you should call the MapControllers order as shown in the code snippet given under to empower attribute-based routing.
app.UseEndpointsendpoints _gt;{ endpoints.MapControllerRoute name: "lapse"_ model: "{controller_Home}_{action_Index}_{id?}" endpoints.MapControllers;};<_pre>An action order is a open and non-static order of a controller class that can feel incoming requests and is invoked based on an action. The ASP.NET Core MVC engine is expert at redirecting an incoming request to the corresponding action order. However_ if there is no action order that matches the request_ a runtime fault will befall.
