Handle Werkzeug 2.1.0 change to Request.get_json().

pallets/werkzeug#2339 changed the behavior of `Request.get_json()`
and the `Request.json` property to raise a `BadRequest` if `Request.get_json()`
is called without `silent=True`, or the `Request.json` property is accessed,
and the content type is not `"application/json"`.

Argument parsing allows parsing from multiple locations, and defaults to
`["json", "values"]`, but if the locations include `"json"` and the content
type is not `"application/json"`, a `BadRequest` is now raised with Werkzeug >= 2.1.0.

Invoking `Request.get_json()` with the `silent=True` parameter now handles
the situation where `"json"` is included in the locations, but the content type
is not `"application/json"`.

flask_restx/reqparse.py

@@ -138,15 +138,21 @@ def source(self, request):
         :param request: The flask request object to parse arguments from
         """
         if isinstance(self.location, six.string_types):
-            value = getattr(request, self.location, MultiDict())
+            if self.location in {"json", "get_json"}:
+                value = request.get_json(silent=True)
+            else:
+                value = getattr(request, self.location, MultiDict())
             if callable(value):
                 value = value()
             if value is not None:
                 return value
         else:
             values = MultiDict()
             for l in self.location:
-                value = getattr(request, l, None)
+                if l in {"json", "get_json"}:
+                    value = request.get_json(silent=True)
+                else:
+                    value = getattr(request, l, None)
                 if callable(value):
                     value = value()
                 if value is not None:

tests/test_reqparse.py

@@ -41,8 +41,9 @@ def test_help(self, app, mocker):
         )
         parser = RequestParser()
         parser.add_argument("foo", choices=("one", "two"), help="Bad choice.")
-        req = mocker.Mock(["values"])
+        req = mocker.Mock(["values", "get_json"])
         req.values = MultiDict([("foo", "three")])
+        req.get_json.return_value = None
         with pytest.raises(BadRequest):
             parser.parse_args(req)
         expected = {
@@ -58,7 +59,8 @@ def test_no_help(self, app, mocker):
         )
         parser = RequestParser()
         parser.add_argument("foo", choices=["one", "two"])
-        req = mocker.Mock(["values"])
+        req = mocker.Mock(["values", "get_json"])
+        req.get_json.return_value = None
         req.values = MultiDict([("foo", "three")])
         with pytest.raises(BadRequest):
             parser.parse_args(req)
@@ -76,9 +78,9 @@ def test_viewargs(self, mocker):
         args = parser.parse_args(req)
         assert args["foo"] == "bar"
 
-        req = mocker.Mock()
+        req = mocker.Mock(["get_json"])
         req.values = ()
-        req.json = None
+        req.get_json.return_value = None
         req.view_args = {"foo": "bar"}
         parser = RequestParser()
         parser.add_argument("foo", store_missing=True)
@@ -101,11 +103,10 @@ def test_parse_unicode_app(self, app):
             args = parser.parse_args()
             assert args["foo"] == "barß"
 
-    @pytest.mark.request_context("/bubble", method="post")
+    @pytest.mark.request_context("/bubble", method="post", content_type='application/json')
     def test_json_location(self):
         parser = RequestParser()
         parser.add_argument("foo", location="json", store_missing=True)
-
         args = parser.parse_args()
         assert args["foo"] is None
 
@@ -856,7 +857,8 @@ def test_source_bad_location(self, mocker):
         assert len(arg.source(req)) == 0  # yes, basically you don't find it
 
     def test_source_default_location(self, mocker):
-        req = mocker.Mock(["values"])
+        req = mocker.Mock(["values", "get_json"])
+        req.get_json.return_value = None
         req._get_child_mock = lambda **kwargs: MultiDict()
         arg = Argument("foo")
         assert arg.source(req) == req.values