Action Results in MVC

HTTP METHODS

The Hypertext Transfer Protocol (HTTP) is designed to enable communications between clients and servers.

HTTP works as a request-response protocol between a client and server.

Four commonly used methods are

• [HttpGet] GET is used to request data from a specified resource.
• [HttpPost] POST is used to send data to a server to create a resource
• [HttpDelete] Delete method is used to delete server data
• [HttpPut] Put method is used to update server data

Action result (Return Types)

Common HTTP Status Codes

Every HTTP transaction has a status code sent back by the server to define how the server handled the transaction. Here is a list of the most common ones.
HTTP Status Code – 200 OK

The request has succeeded. The information returned with the response is dependent on the method used in the request.

HTTP Status Code – 300 Multiple Choices

The requested resource has different choices and cannot be resolved into one. For example, there may be several index.html pages

HTTP Status Code – 301 Moved Permanently

The requested resource has been assigned a new permanent URI and any future references to this resource should use one of the returned URIs.

HTTP Status Code – 302 Found

The requested resource resides temporarily under a different URI. Since the redirection might be altered on occasion, the client SHOULD continue to use the Request-URI for future requests.

HTTP Status  403 – Forbidden
You can encounter the 403 Forbidden error page when the server understands the client’s request clearly, but for some reasons refuses to fulfil it.

HTTP Status  404 – Not Found

404 is the most well-known HTTP status code out there when the server doesn’t find anything on the requested location. The browser returns a 404 HTML page .

Exception handling -Try-Catch

Exception handling is the process of responding to the occurrence of exceptional conditions requiring special processing. In ASP.NET we can handle exceptions in the following two ways:

• Try-catch-finally block at method level
• Using Application_Error

Try-catch-finally

Change the Index as in the following. Here we are generating an exception at “c = a / b;” inside the try block (next slide).

In the catch we are retuning a different view “Error”. If you run the application you will get an Error page in the browser. In an actual project we can also use the catch block to log the error information.