Learn About Action Selectors In ASP.NET MVC

[ActionName("GetTime")]
public String Time() {
    return @"Current Time is: " + DateTime.Now;
}

Now build and run the application with this /Home/Time URL, you should see the following error, it is because of the [ActionName] action selector.

By using this action selector, you have changed the name of the action method, now the URL /Home/GetTime only works instead of /Home/Time. See the output below.

Hence you have seen that the [ActionName] action selector can change the name of the action method.

NonAction

[NonAction] attribute is an action selector that indicates a public method of the controller is not an action method. We use the [NonAction] attribute when we want a method that shouldn’t be treated as an action method.

As you know, the Controller contains the methods that are public and are termed action methods because of one-to-one mapping with the HTTP-requested URL. But when you want that, any method of Controller shouldn’t be treated as an action method, then you have to use the [NonAction] attribute.

Example

Now let’s make some changes in the HomeController of ActionSelectorsDemo project. Add another method named “GetTimeMethod” whose responsibility is also to print the current time. And then call this newly added method into the “Time” action method. You can see the code of both action methods below.

[ActionName("GetTime")]
public String Time() {
    return GetTimeMethod();
}
public String GetTimeMethod() {
    return @"Current Time is: " + DateTime.Now;
}

Now observe the output, after building and running the application. When we run the application with this /Home/Time URL, we’ll see an error because we are bound to use the name “GetTime” for this action method because of the [ActionName] action selector.

Now when you run the application with this /Home/GetTimeMethod, you should see the output given below.

As you have seen, you are still able to access GetTimeMethod while there is no need to access it because it is producing the same output as produced by the “GetTime” action method. So we need to restrict its access by using the [NonAction] action selector because it makes the method a non-action method. So it can’t be called in the request URL at all. Let’s see its example. The code of the “GetTimeMethod” method will become as follows.

[NonAction]  
public String GetTimeMethod() {  
    return @ "Current Time is: " + DateTime.Now;  
}  

So the output will become.

So as you have seen, the [NonAction] action selector is used to make an action method Non-Action method.

ActionVerbs

You have seen in the beginning of this article what actions are. And you should also know “Verbs” which are defined as “words which are used to describe an action, state or occurrence of an event”. So as the name suggests, “ActionVerbs” can be defined as “the words that describe the action, purpose, and state of the action method of a Controller”. Now, let’s move towards its technical explanation.

When an HTTP request comes to the controller on a specific action method, then this selector helps us to select the correct action method based on the HTTP requested method. It also helps us to create more than one action method with the same name, also referred to as overloading. So to differentiate these action methods, we use action verbs. We’ll see its example later in this article.

MVC framework supports different ActionVerbs, shown as follows.

• HttpGet: It is used to get information from the server. When this applies to the action method, it restricts the action method to accept only HTTP GET requests.
• HttpPost: It is used to post information on the server. When this applies to the action method, it restricts the action method to accept only HTTP POST requests.
• HttpPut: It is used to create or replace existing information on the server, but can’t update. And when this applies to the action method, it restricts the action method to accept only HTTP PUT requests.
• HttpDelete: It is used to delete any existing information from the server. When this applies to an action method, it restricts the action method to accept only HTTP Delete requests.
• HttpPatch: It is used to fully or partially update any existing information on the server. When this applies to the action method, it restricts the action method to accept only HTTP Patch requests.
• HttpOptions: It is used to represent information about the options of the communication that are supported by the web server.

Action verbs are very popular in using APIs. In the MVC framework, if you don’t apply any attribute of the action selector on the top of the action method when the method is called from the HTTP request, then that HTTP request will behave like a HttpGet request by default.

Conclusion

I hope this article has helped you understand all the concepts of action selectors in ASP.NET MVC. And stay tuned for my next article. If you have any queries then feel free to contact me in the comments section. Also, giving feedback, either positive or negative, will help me to make my articles better and increase my enthusiasm to share my knowledge.