unicode type on a param causes Swagger documentation to crash under Python 2

[Drarok]

Code

# Note this is Python 2 code
@api.route("/search")
class Search(Resource):
    @api.param(
        "search", type=unicode, default=None,
        description="etc etc etc",
    )
    def get(self):
        pass

Repro Steps (if applicable)

1. Define a resource as above
2. Attempt to access Swagger documentation
3. Broken!

Expected Behavior

I would expect unicode to be a valid type.

Actual Behavior

Swagger documentation is unavailable, console shows the following error:

[start]   File "…/json/encoder.py", line 184, in default
[start]     raise TypeError(repr(o) + " is not JSON serializable")
[start] TypeError: <type 'unicode'> is not JSON serializable

Error Messages/Stack Trace

[start] Traceback (most recent call last):
[start]   File "…/my_project/app/lib/flask/app.py", line 1813, in full_dispatch_request
[start]     rv = self.dispatch_request()
[start]   File "…/my_project/app/lib/flask/app.py", line 1799, in dispatch_request
[start]     return self.view_functions[rule.endpoint](**req.view_args)
[start]   File "…/my_project/app/lib/flask_restplus/api.py", line 329, in wrapper
[start]     return self.make_response(data, code, headers=headers)
[start]   File "…/my_project/app/lib/flask_restplus/api.py", line 350, in make_response
[start]     resp = self.representations[mediatype](data, *args, **kwargs)
[start]   File "…/my_project/app/lib/flask_restplus/representations.py", line 27, in output_json
[start]     dumped = dumps(data, **settings) + "\n"
[start]   File "…/python2.7/json/__init__.py", line 251, in dumps
[start]     sort_keys=sort_keys, **kw).encode(obj)
[start]   File "…/python2.7/json/encoder.py", line 209, in encode
[start]     chunks = list(chunks)
[start]   File "…/python2.7/json/encoder.py", line 434, in _iterencode
[start]     for chunk in _iterencode_dict(o, _current_indent_level):
[start]   File "…/python2.7/json/encoder.py", line 408, in _iterencode_dict
[start]     for chunk in chunks:
[start]   File "…/python2.7/json/encoder.py", line 408, in _iterencode_dict
[start]     for chunk in chunks:
[start]   File "…/python2.7/json/encoder.py", line 408, in _iterencode_dict
[start]     for chunk in chunks:
[start]   File "…/python2.7/json/encoder.py", line 408, in _iterencode_dict
[start]     for chunk in chunks:
[start]   File "…/python2.7/json/encoder.py", line 332, in _iterencode_list
[start]     for chunk in chunks:
[start]   File "…/python2.7/json/encoder.py", line 408, in _iterencode_dict
[start]     for chunk in chunks:
[start]   File "…/python2.7/json/encoder.py", line 442, in _iterencode
[start]     o = _default(o)
[start]   File "…/python2.7/json/encoder.py", line 184, in default
[start]     raise TypeError(repr(o) + " is not JSON serializable")
[start] TypeError: <type 'unicode'> is not JSON serializable

Environment

• Python 2.7.16
• Flask 1.0.2
• Flask-RESTPlus 0.12.1

[j5awry]

We'll chat about this, but my gut is to not check into Python2 bugs with the Py2 death date approaching quickly. We've got limited resources.

Does this work under Py3?

[Drarok]

Python 3 removes the unicode type since its default str type supports unicode, so I don't think it's an issue under Py3.

[Drarok]

I've found a way to fix this:

diff --git a/flask_restplus/swagger.py b/flask_restplus/swagger.py
index 77c364b..21f9555 100644
--- a/flask_restplus/swagger.py
+++ b/flask_restplus/swagger.py
@@ -40,6 +40,9 @@ PY_TYPES = {
     None: 'void'
 }
 
+if six.PY2:
+    PY_TYPES[unicode] = 'string'
+
 RE_URL = re.compile(r'<(?:[^:<>]+:)?([^<>]+)>')
 
 DEFAULT_RESPONSE_DESCRIPTION = 'Success'

That said, it might be pretty unusual to define a param as type=unicode – Flask-RESTPlus appears to use unicode types internally regardless. The issue which caused me to define my params as unicode instead of str was elsewhere.