Ruby-on-rails – Rails POST, PUT, GET

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After I generate a scaffold, Rails gives me the ability to POST to items.xml which will create a new item. A GET to items.xml will simply list them all. Where does Rails specify which method in the controller (create or index, respectively) will be called, based on the type of action I am performing?

More specifically, POST calls methodA but GET to the same URL calls methodB. Where is this specified? Where does Rails make the determination to call the index method of the controller?

Best Answer

I believe it's specified by REST. Here's a list for ya:

GET    /items        #=> index
GET    /items/1      #=> show
GET    /items/new    #=> new
GET    /items/1/edit #=> edit
PUT    /items/1      #=> update
POST   /items        #=> create
DELETE /items/1      #=> destroy

Edited to add to get all those routes, in config/routes.rb, simply add map.resources :items

Related Solutions

What’s the difference between a POST and a PUT HTTP REQUEST

HTTP PUT:

PUT puts a file or resource at a specific URI, and exactly at that URI. If there's already a file or resource at that URI, PUT replaces that file or resource. If there is no file or resource there, PUT creates one. PUT is idempotent, but paradoxically PUT responses are not cacheable.

HTTP 1.1 RFC location for PUT

HTTP POST:

POST sends data to a specific URI and expects the resource at that URI to handle the request. The web server at this point can determine what to do with the data in the context of the specified resource. The POST method is not idempotent, however POST responses are cacheable so long as the server sets the appropriate Cache-Control and Expires headers.

The official HTTP RFC specifies POST to be:

Annotation of existing resources;
Posting a message to a bulletin board, newsgroup, mailing list, or similar group of articles;
Providing a block of data, such as the result of submitting a form, to a data-handling process;
Extending a database through an append operation.

HTTP 1.1 RFC location for POST

Difference between POST and PUT:

The RFC itself explains the core difference:

The fundamental difference between the POST and PUT requests is reflected in the different meaning of the Request-URI. The URI in a POST request identifies the resource that will handle the enclosed entity. That resource might be a data-accepting process, a gateway to some other protocol, or a separate entity that accepts annotations. In contrast, the URI in a PUT request identifies the entity enclosed with the request -- the user agent knows what URI is intended and the server MUST NOT attempt to apply the request to some other resource. If the server desires that the request be applied to a different URI, it MUST send a 301 (Moved Permanently) response; the user agent MAY then make its own decision regarding whether or not to redirect the request.

Additionally, and a bit more concisely, RFC 7231 Section 4.3.4 PUT states (emphasis added),

4.3.4. PUT

The PUT method requests that the state of the target resource be created or replaced with the state defined by the representation enclosed in the request message payload.

Using the right method, unrelated aside:

One benefit of REST ROA vs SOAP is that when using HTTP REST ROA, it encourages the proper usage of the HTTP verbs/methods. So for example you would only use PUT when you want to create a resource at that exact location. And you would never use GET to create or modify a resource.

Php – Detecting request type in PHP (GET, POST, PUT or DELETE)

By using

$_SERVER['REQUEST_METHOD']

Example

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
     // The request is using the POST method
}

For more details please see the documentation for the $_SERVER variable.

Best Answer

Related Solutions

What’s the difference between a POST and a PUT HTTP REQUEST

Php – Detecting request type in PHP (GET, POST, PUT or DELETE)

Example

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