问题
I'm developing a RESTful API service which initially will only be accepting and responding in JSON format. I want to follow standards and in case of requester's Accept header was different than JSON I want to respond with 406 HTTP status code to inform the requester I cannot output data in other format.
According to W3 I "SHOULD include an entity containing a list of available entity characteristics and location(s) from which the user or user agent can choose the one most appropriate" in my response.
How do I do that, because the above explanation doesn't tell me much. What is the mentioned entity?
Any ideas/suggestions?
EDIT
Initially I thought that maybe could be a comma separated list in Content-Type header but after rethinking maybe I should do the same thing browsers do and use Accept header? This makes much more sense actually, but I cannot find any information to support this.
回答1:
Three issues here:
First, the note from RFC 2616 is meant to address URI schemes where responses of different types are made available at various URI's, such as "/path/to/thing.xml" vs "/path/to/thing.json". That's not always a popular choice, but if you can do that, do so and include hyperlinks to each one in the "entity"; that is, in the body of the response. Since the RFC doesn't mandate a Content-Type or processing model for such links, you're on your own regarding how to return them, but HTML with <a> tags is common and useful.
If you don't want to expose multiple types at separate URI's, but just want to expose one type at the original URI, then it's perfectly fine to respond with 406 and an entity that simply says which types the resource can emit.
Second, note that most web browsers send */* in the Accept header (with a low quality value), which should match any Content-Type. In addition, the spec says "...if no Accept header field is present, then it is assumed that the client accepts all media types." So the cases where you should be raising 406 are rare.
Third, don't emit a Content-Type response header that is anything other than the Content-Type of the response entity. It should not be used to list acceptable types. You should also not emit a response header named 'Accept'; the 'Accept' header is for requests only; see http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.1
来源：https://stackoverflow.com/questions/4422980/how-to-properly-send-406-status-code