Routing Variations in WEB API

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Routing Variations in ASP.NET Web API

In this article, I am going to discuss Routing Variations in ASP.NET WEB API with examples. Please read our previous article before proceeding to this article where we discussed the basics of Routing in ASP.NET Web API. As part of this article, we are going to discuss the following important pointers.

1. Understanding HTTP Methods.
2. Routing Variation in Web API by Action Name.
3. Understanding the NonAction attribute in ASP.NET Web API.

Understanding HTTP Verbs in ASP.NET Web API.

In the last article, we discussed using the default naming convention i.e. default route provided by ASP.NET Web API Framework. Instead of using the default naming convention for the HTTP methods, you can also explicitly specify the HTTP method for action by decorating the action method with the HttpGet, HttpPut, HttpPost, or HttpDelete attribute.

Example: HttpGet, HttpPut, HttpPost, or HttpDelete Attribute in ASP.NET MVC

Let us understand this with an example. Please consider the following Student controller.

In the above example, the FindAllStudents and FindStudentById actions are mapped to the GET request, while the RemoveStudent action is mapped to DELETE Request and the AddStudent action is mapped to POST Request. If you want to allow multiple HTTP verbs on a single action method, or if you to allow HTTP methods other than the GET, PUT, POST, and DELETE, then you need to use the AcceptVerbs attribute, which takes a list of HTTP methods as shown in the below image.

In the above example, the FindStudentById action method is mapped to both GET and HEAD HTTP Request.

Routing Variation in Web API by Action Name

With the default routing template, the ASP.NET Web API Framework uses the HTTP method to select the action. However, if you want you can change this default behavior. Suppose, you want to create your own route where the action name is included as part of the URI, Then you need to create a new route as shown in the below image.

In the above route template, the {action} parameter names the action method on the controller. With this style of routing, it is mandatory to use the HTTP verb attributes to specify the allowed HTTP methods. Let us understand this with an example. Please consider the following controller.

In the above example, a GET request for “api/Student/FindAllStudents” would map to the FindAllStudents action method. In ASP.NET Web API by using the ActionName attribute you can also override the action method name. In the below Student Controller class, we have two actions which map to “api/Student/Image“. One action method supports the GET request while the other one supports the  POST HTTP request.

Understanding the NonAction Attribute in ASP.NET Web API:

If you want to prevent an action method from getting invoked as a response to an HTTP request, then you need to decorate that action method with the NonAction attribute. This tells the ASP.NET Web API Framework that the method is not an action, even if it would match the routing rules.

As of now, we have discussed a high-level overview of ASP.NET Web API Routing. In the next article, I am going to discuss how the WEB API Framework matches a URI to a route, selects a controller, and then selects the action to invoke. Here, in this article, I try to explain Routing Variations in WEB API step by step with some examples. I hope this Routing Variation in WEB API article will help you with your need.