Actions, Controllers and Results

What is an Action?

Most of the requests received by a Play application are handled by an action.

An action is basically a Java method that processes the request parameters, and produces a result to be sent to the client.

@simple-action

An action returns a play.mvc.Result value, representing the HTTP response to send to the web client. In this example ok constructs a 200 OK response containing a text/plain response body. For more examples of HTTP responses see play.mvc.Results methods.

Controllers

A controller is nothing more than a class extending play.mvc.Controller that groups several action methods.

@full-controller

The simplest syntax for defining an action is a method with no parameters that returns a Result value, as shown above.

An action method can also have parameters:

@params-action

These parameters will be resolved by the Router and will be filled with values from the request URL. The parameter values can be extracted from either the URL path or the URL query string.

Results

Let’s start with simple results: an HTTP result with a status code, a set of HTTP headers and a body to be sent to the web client.

These results are defined by play.mvc.Result, and the play.mvc.Results class provides several helpers to produce standard HTTP results, such as the ok method we used in the previous section:

@simple-result

Here are several examples that create various results:

@other-results

All of these helpers can be found in the play.mvc.Results class.

Redirects are simple results too

Redirecting the browser to a new URL is just another kind of simple result. However, these result types don't have a response body.

There are several helpers available to create redirect results:

@redirect-action

The default is to use a 303 SEE_OTHER response type, but you can also specify a more specific status code:

@temporary-redirect-action