un-:processable? request returns "Unprocessable entity." with "Content-Type: application/json;charset=UTF-8"

[ghost]

The following should not happen:

# http get localhost:3000/api/v1/...
HTTP/1.1 422 Unprocessable Entity
Content-Length: 21
Content-Type: application/json;charset=UTF-8
Date: Tue, 28 Mar 2017 15:24:09 GMT
Server: Jetty(7.6.13.v20130916)
Vary: Accept

Unprocessable entity.

I assume it is caused by:

(lib/defresource ... []
  :available-media-types ["application/json"]
  ...)

IMO Liberator should decide: Either return a default text in the given Content-Type, or return nothing at all. What it does right now creates weird error messages, when my tests fail:

FAIL "GET /... - status" at (test_handler.clj:50)
    Expected: 200
      Actual: 422
Exception in thread "main" java.lang.Exception: JSON error (unexpected character): U, compiling:(.../test_handler.clj:46:1)
        at clojure.lang.Compiler.load(Compiler.java:7391)
        ...

[ordnungswidrig]

Thanks for the report this is actually a bug that is related to #82. The problem is that the default response for 422 in liberator is a string "Unprocessable entity" but the error response makes use of the negotiated content type, application/json in this case. Liberator threats Strings as a literal response which leads to the observer behaviour.

A workaround is to implement :handle-unprocessable-entity and return a proper response according to the content type.