'non-iterable ellipsis in Flask_Restful parser.parse_args()
I've come back to a project I worked on previously, utilising flask RESTful, though whenever I attempt a post request the line args = parser.parse_args() breaks the code, giving an error reading:
File "/usr/local/lib/python3.9/site-packages/werkzeug/datastructures.py", line 554, in update
for key, value in iter_multi_items(mapping):
TypeError: cannot unpack non-iterable ellipsis object
For some reason the parser seems to be having issues with its own arguments, the post function is:
def post(self):
from flask_restful import reqparse
parser = reqparse.RequestParser()
parser.add_argument('rate', type=int, help='Rate cannot be converted')
parser.add_argument('name')
args = parser.parse_args()
Any help or direction would be greatly appreciated.
-- Edit
To give more context, my init file looks like this, the error occurring when the POST function is called in postman.
from flask import Flask, g
from flask_restful import Resource, Api, reqparse
import os
import shelve
app = Flask(__name__)
api = Api(app)
def get_db():
db = getattr(g, '_database', None)
if db is None:
db = g._database = shelve.open("rates.db")
return db
@app.teardown_appcontext
def teardown_db(exception):
db = getattr(g, '_database', None)
if db is not None:
db.close()
@app.route("/")
def index():
return "Hello World"
class RateList(Resource):
def get(self):
shelf = get_db()
keys = list(shelf.keys())
devices = []
for key in keys:
devices.append(shelf[key])
return {'message' : 'Success', 'data' : devices}, 200
def post(self):
parser = reqparse.RequestParser()
parser.add_argument('rate', type=int, help='Rate cannot be converted')
parser.add_argument('name')
args = parser.parse_args()
shelf = get_db()
shelf[args['rate']] = args
return {'message' : 'Rate registered', 'data' : args}, 201
class Rate(Resource):
def get(self, rate):
shelf = get_db()
if not(rate in shelf):
return {'message' : 'Rate not found', 'data' : {}}, 404
return {'message' : 'Rate found', 'data' : shelf[rate]}, 200
def delete(self, rate):
shelf = get_db()
if not(rate in shelf):
return {'message' : 'Rate not found', 'data' : {}}, 404
del shelf[rate]
return {'message' : 'Rate deleted', 'data' : {}}, 200
api.add_resource(RateList, '/Rate')
api.add_resource(Rate, '/Rate/<string:rate>')
Docker-compose file:
version: '3.4'
services:
stock-registry:
build: .
volumes:
- .:/usr/src/app
ports:
- 5001:80
Dockerfile:
FROM python:3
WORKDIR /usr/src/app
COPY requirements.txt ./
RUN pip install --no-cache-dir -r requirements.txt
COPY . .
CMD ["python", "./run.py"]
Run.py:
from stock_registry import app
app.run(host='0.0.0.0', port=80, debug=True)
-- Edit 2
The JSON body sent on the post request, using postman:
{
"rate" : 1,
"name" : "Test"
}
The complete error log that shows when this is attempted:
172.22.0.1 - - [30/Jun/2021 12:37:12] "POST /shares HTTP/1.1" 500 -
Traceback (most recent call last):
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1997, in __call__
return self.wsgi_app(environ, start_response)
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1985, in wsgi_app
response = self.handle_exception(e)
File "/usr/local/lib/python3.9/site-packages/flask_restful/__init__.py", line 265, in error_router
return original_handler(e)
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1540, in handle_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.9/site-packages/flask/_compat.py", line 32, in reraise
raise value.with_traceback(tb)
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1982, in wsgi_app
response = self.full_dispatch_request()
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1614, in full_dispatch_request
rv = self.handle_user_exception(e)
File "/usr/local/lib/python3.9/site-packages/flask_restful/__init__.py", line 265, in error_router
return original_handler(e)
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1517, in handle_user_exception
reraise(exc_type, exc_value, tb)
File "/usr/local/lib/python3.9/site-packages/flask/_compat.py", line 32, in reraise
raise value.with_traceback(tb)
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1612, in full_dispatch_request
rv = self.dispatch_request()
File "/usr/local/lib/python3.9/site-packages/flask/app.py", line 1598, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File "/usr/local/lib/python3.9/site-packages/flask_restful/__init__.py", line 446, in wrapper
resp = resource(*args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/flask/views.py", line 84, in view
return self.dispatch_request(*args, **kwargs)
File "/usr/local/lib/python3.9/site-packages/flask_restful/__init__.py", line 550, in dispatch_request
resp = meth(*args, **kwargs)
File "/usr/src/app/stock_registry/__init__.py", line 65, in post
args = parser.parse_args()
File "/usr/local/lib/python3.9/site-packages/flask_restful/reqparse.py", line 261, in parse_args
value, found = arg.parse(req)
File "/usr/local/lib/python3.9/site-packages/flask_restful/reqparse.py", line 143, in parse
source = self.source(request)
File "/usr/local/lib/python3.9/site-packages/flask_restful/reqparse.py", line 101, in source
values.update(value)
File "/usr/local/lib/python3.9/site-packages/werkzeug/datastructures.py", line 554, in update
for key, value in iter_multi_items(mapping):
TypeError: cannot unpack non-iterable ellipsis object
Solution 1:[1]
I had the same issue. Can you share your version numbers of flask and of flask-restful?
What worked for me is updating both packages, since somehow I apparently got 2 versions that don't work together in my environment. I upgraded them to the following and now it's working:
Try: pip install flask==2.0.1 flask-restful==0.3.9
Hope this works!
Solution 2:[2]
It is a version compatibility error in flask or flask-restful or werkzeug.
What worked for me:
Werkzeug==1.0.1
Flask==0.11.1
Flask-RESTful==0.3.5
Sources
This article follows the attribution requirements of Stack Overflow and is licensed under CC BY-SA 3.0.
Source: Stack Overflow
| Solution | Source |
|---|---|
| Solution 1 | Tom H. |
| Solution 2 | Archit Saxena |