Add JSONIFY_END_WITH_NEWLINE config variable

CHANGES

@@ -53,7 +53,11 @@ Version 1.0
 - Add "pretty" and "compressed" separators definitions in jsonify() method.
   Reduces JSON response size when JSONIFY_PRETTYPRINT_REGULAR=False by removing
   unnecessary white space included by default after separators.
-
+- JSON responses are now terminated with a newline character, because it is a
+  convention that UNIX text files end with a newline and some clients don't
+  deal well when this newline is missing. See
+  https://github.com/mitsuhiko/flask/pull/1262 -- this came up originally as a
+  part of https://github.com/kennethreitz/httpbin/issues/168
 
 Version 0.10.2
 --------------

flask/json.py

@@ -200,8 +200,9 @@ def htmlsafe_dump(obj, fp, **kwargs):
 
 def jsonify(*args, **kwargs):
     """Creates a :class:`~flask.Response` with the JSON representation of
-    the given arguments with an :mimetype:`application/json` mimetype.  The arguments
-    to this function are the same as to the :class:`dict` constructor.
+    the given arguments with an :mimetype:`application/json` mimetype.  The
+    arguments to this function are the same as to the :class:`dict`
+    constructor.
 
     Example usage::
 
@@ -241,9 +242,13 @@ def get_current_user():
         indent = 2
         separators = (', ', ': ')
 
-    return current_app.response_class(dumps(dict(*args, **kwargs),
-        indent=indent, separators=separators),
+    # Note that we add '\n' to end of response
+    # (see https://github.com/mitsuhiko/flask/pull/1262)
+    rv = current_app.response_class(
+        (dumps(dict(*args, **kwargs), indent=indent, separators=separators),
+         '\n'),
         mimetype='application/json')
+    return rv
 
 
 def tojson_filter(obj, **kwargs):

tests/test_basic.py

@@ -942,7 +942,7 @@ def test_make_response_with_response_instance():
         rv = flask.make_response(
             flask.jsonify({'msg': 'W00t'}), 400)
         assert rv.status_code == 400
-        assert rv.data == b'{\n  "msg": "W00t"\n}'
+        assert rv.data == b'{\n  "msg": "W00t"\n}\n'
         assert rv.mimetype == 'application/json'
 
         rv = flask.make_response(
@@ -963,7 +963,7 @@ def test_jsonify_no_prettyprint():
     app = flask.Flask(__name__)
     app.config.update({"JSONIFY_PRETTYPRINT_REGULAR": False})
     with app.test_request_context():
-        compressed_msg = b'{"msg":{"submsg":"W00t"},"msg2":"foobar"}'
+        compressed_msg = b'{"msg":{"submsg":"W00t"},"msg2":"foobar"}\n'
         uncompressed_msg = {
             "msg": {
                 "submsg": "W00t"
@@ -982,7 +982,7 @@ def test_jsonify_prettyprint():
     with app.test_request_context():
         compressed_msg = {"msg":{"submsg":"W00t"},"msg2":"foobar"}
         pretty_response =\
-            b'{\n  "msg": {\n    "submsg": "W00t"\n  }, \n  "msg2": "foobar"\n}'
+            b'{\n  "msg": {\n    "submsg": "W00t"\n  }, \n  "msg2": "foobar"\n}\n'
 
         rv = flask.make_response(
             flask.jsonify(compressed_msg), 200)