Action Selectors in ASP.NET MVC

Action Selectors in ASP.NET MVC

• Action Selectors are built-in attributes provided in ASP.NET MVC and are directly influence our Controller's action methods.
• Action Selectors guide the URL Routers to respective action method of Controller which then opens up View for the user.
• Action Selectors are simple C# classes.
• There are 3 types of Action Selectors available in ASP.NET MVC, named as:
  • ActionName
  • NonAction
  • ActionVerbs
• So, let's discuss each of them in detail:

1. ActionName Selector in ASP.NET MVC

• ActionName Selector (as the name suggests) is used to change the name of Action from the name of Controller's Method.
• Let's open the StudentController.cs file which we created in Tut # 06: Create a New Controller in ASP.NET MVC.
• I have added an action Method here Get() and above this method I have placed [ActionName("GetAction")], as shown in below figure:

• If we want to access this action method Get(), then we have to place localhost:12345/Student/Get in our browser.
• But after placing the ActionName Selector, now we have to use localhost:12345/Student/GetAction in order to call Get() Method.
• So, in this case the name of action is GetAction but the name of method is Get.
• But if we don't use ActionName Selector, then name of both Action and Method is Get.
• Let's have a look at what's the effect of ActionName Selector:

• As you can see in above figure that when we have used Get then we received Server Error.
• When we have used GetAction (assigned in ActionName) then our Method Get() is called.
• Here's the video demonstration of ActionName Selector in detail:

2. NonAction Selector in ASP.NET MVC

• NonAction Selector is another built-in attribute of ASP.NET MVC and as the name name suggests, it is used to remove the Action from action method.
• If you place NonAction Selector before an action method in your Controller then you won't be able to access that method directly from its action.
• URL Router will think this method doesn't exist, if its called directly.
• Let's add some code in our StudentController.cs file, as shown in below figure:

• I have added [NonAction] before our action method Get1(), that's how we specify nonAction Selector in ASP.NET MVC.
• If you have a look in the Index Method then you can see I have called Get1 there.
• Now when we open the Home Page of our site, then this Get1 action method will be called and it will work fine.
• But if we want to call the Get1 action method directly then it won't open up and will give us a Server error.
• That's because we have placed nonAction Selector before it.
• Results of both Home page & direct calling the action method are shown in below figure:

• So, its cleared from the above figure that nonAction has removed the action from our method and now its just a simple public method, which we can call from inside but no one can access it from outside directly.
• Here's the video demonstration of nonAction Selector, must watch it for live action:

3. ActionVerbs Selector in ASP.NET MVC

• ActionVerbs Selector is third built-in selector in ASP.NET MVC and is used to assign some specified HTTP request to action methods.
• It helps the URL router in selection of correct action method.
• Let's say you have two action methods in your project and they have a same name but you want to use one for GETting data and the second one for POSTing data.
• Let's have a look at the similar situation in below code:

• AS you can see in above figure that we have written two action methods of the same name Get1.
• So, now if you call it in your browser then you will get Server Error, as shown in below figure:

• So, now let's place our ActionVerbs Selector before one of these action methods, which one we want to call.
• I have placed the [HttpGet] before second action method and now because of this ActionVerbs Selector,URL Router will know which action method to call.

• Now when you open Get1 page, it will open fine.
• These ActionVerbs Selector are supported by ASP.NET MVC:
• • HttpPost
  • HttpGet
  • HttpDelete
  • HttpPut
  • HttpOptions
  • HttpPatch
• Here's the video demonstration of ActionVerbs Selector in detail: