Accepting a JSON Request Body
=============================
A common need when building a restful API is the ability to accept a JSON
encoded entity from the request body.
An example for such an API could be a blog post creation.
Example API
-----------
In this example we will create an API for creating a blog post. The following
is a spec of how we want it to work.
Request
~~~~~~~
In the request we send the data for the blog post as a JSON object. We also
indicate that using the ``Content-Type`` header:
.. code-block:: text
POST /blog/posts
Accept: application/json
Content-Type: application/json
Content-Length: 57
{"title":"Hello World!","body":"This is my first post!"}
Response
~~~~~~~~
The server responds with a 201 status code, telling us that the post was
created. It tells us the ``Content-Type`` of the response, which is also
JSON:
.. code-block:: text
HTTP/1.1 201 Created
Content-Type: application/json
Content-Length: 65
Connection: close
{"id":"1","title":"Hello World!","body":"This is my first post!"}
Parsing the request body
------------------------
The request body should only be parsed as JSON if the ``Content-Type`` header
begins with ``application/json``. Since we want to do this for every request,
the easiest solution is to use an application before middleware.
We simply use ``json_decode`` to parse the content of the request and then
replace the request data on the ``$request`` object::
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\ParameterBag;
$app->before(function (Request $request) {
if (0 === strpos($request->headers->get('Content-Type'), 'application/json')) {
$data = json_decode($request->getContent(), true);
$request->request->replace(is_array($data) ? $data : array());
}
});
Controller implementation
-------------------------
Our controller will create a new blog post from the data provided and will
return the post object, including its ``id``, as JSON::
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
$app->post('/blog/posts', function (Request $request) use ($app) {
$post = array(
'title' => $request->request->get('title'),
'body' => $request->request->get('body'),
);
$post['id'] = createPost($post);
return $app->json($post, 201);
});
Manual testing
--------------
In order to manually test our API, we can use the ``curl`` command line
utility, which allows sending HTTP requests:
.. code-block:: bash
$ curl http://blog.lo/blog/posts -d '{"title":"Hello World!","body":"This is my first post!"}' -H 'Content-Type: application/json'
{"id":"1","title":"Hello World!","body":"This is my first post!"}