Slim 3 Request Content Type

The encoding type of your request matters. In Slim 3 we try to support a wide variety of different formats to make sure you don't have to. I want to take some time to demystify how this process works. Let's take a look.

Developers often overlook encoding on form submissions, blissfully unaware that the default encoding type is application/x-www-form-urlencoded. It becomes a problem when developers are interested in building APIs. Typically when I build an API i like to use application/json, because JSON is just so wonderful to work with. However tools like google chrome's extension POSTMAN can be a bit unweildy for some, so I hope to cover off a bit of Slim internals and how the encoding type is handled and why it is that way.

First off I want to talk about what PHP does and doesn't do. As we all know PHP has 2 very helpful superglobals $_GET, $_ POST. What you might not realize is that there is no $_PUT or $_HEAD or $_PATCH, or any other HTTP Verb. WTF?!?! Well what does slim do? Well Slim handles this for you, via Media Parsers and reading php://input directly. The media parsers have different strategies on how to decode/parse the actual request body with is retrieved through php://input.

Let's take a look at what a request looks like.

PUT /user/1 HTTP/1.1
User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)
Content-Type: application/json; charset=utf-8
Content-Length: 88
Accept-Language: en-us
Accept-Encoding: gzip, deflate
Connection: Keep-Alive
{ "username" : "abc" }

In the above we see a PUT request that sets a new username to user/1. Slim will automatically parse this request body because it knows what to do with application/json. Tracing through the Request's class code shows that the parsedBody is not set until you try and access the body message the first time.

Accessing the parsed body's username key will result in the expected "abc".

$username = $request->getParsedBody()['username'];
//$username = "abc";

Default Media Parsers

  • application/x-www-form-urlencoded
  • text/xml
  • application/xml
  • application/json
  • POST ONLY ['multipart/form-data']

Please note that text/json IS NOT HANDLED BY DEFAULT. I am working on getting that changed ;)

If you find yourself with a blank parsed body, do check your Content-Type header and make sure that its one supported by Slim.

I hope this helps you out!

o7 Happy Coding

Written by Glenn Eggleton on Tuesday February 2, 2016
Permalink - Chapter: Slim