request.format returning */*

Question

I'm currently developing an API for my application on RoR

As an example, I created some XML, loaded with all the info I need to create the object, let's say a Person, and using Curl I submitted it to my application

I'm able to call exactly the create action I want from the controller and the hash params of the object are being passed correctly

But now I need to apply a different behaviour if request was made or not with XML, what is bothering me is why in the controller request.format gives */*.

Any clues?

curl -v -H "Content-Type: application/xml; charset=utf-8" --data-ascii @client.xml  http://foo.com:3000/clients?api_key=xxx

def create
  logger.debug request.format # produces "*/*"
  if request.format.xml?
    # never gets here 
  end
end

Answer 1

*/* means that the user-agent accepts all formats and doesn't care what format you give it. I believe Safari does this, among others. By default, curl sends an Accept header of */*.

Here is a dump of the headers curl sends by default:

User-Agent: curl/7.18.1 (i386-apple-darwin9.6.0) libcurl/7.18.1 zlib/1.2.3
Host: example.com
Accept: */*
Content-Type: 

However, in this case, it looks like you want to send back XML if the payload sent to you was XML? If that's the case, you want to check the request's Content-Type header directly. i.e., request.content_type is the method you want.

Addenda: I thought a bit more about this, and I think the best approach is to first check request.format and only if that is inconclusive check request.content_type. Essentially, the HTTP spec provides for clients being able to tell servers that "I'm giving you XML, but I want JSON back." The Accept header is how clients tell you what they want back, and if someone actually sends it, you should honor that. Only use the request's Content-Type as a hint if the client didn't specify.