We have talked about routes, and how to pass parameters to controllers. Let's now talk about what we can do with the controller.

The method defined in the route must return a play.api.mvc.Action instance. The Action type is a thin wrapper around the type Request[A] => Result, where Request[A] identifies an HTTP request and Result is an HTTP response.

Composing the response

An HTTP response, as we saw in Chapter 7, Web APIs, is composed of:

  • the status code (such as 200 for a successful response, or 404 for a missing page)
  • the response headers, a key-value list indicating metadata related to the response
  • The response body. This can be HTML for web pages, or JSON, XML or plain text (or many other formats). This is generally the bit that we are ...

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