POST method in RESTful API works on HTTPie but not on Android/Postman

Question

I wrote the POST method in RESTful API of Flask and successfully added data to the server using HTTPie, a command line HTTP client. But when I tried it on Android there was an error. Here is the code of the client:

@app.route('/factories', methods=['POST'])
def create_factory():
    if not request.json or not 'fac_name' in request.json:
        abort(404)
    factory = {
        'id': factories[-1]['id'] + 1,
        'fac_name': request.json['fac_name'],
        'lat': request.json['lat'],
        'lng': request.json['lng']
    }

    factories.append(factory)
    return jsonify({'factory': factory}), 201

The HTTPie result is like this:

The error of Flask:

192.168.0.101 - - [13/May/2019 03:37:44] "POST /factories HTTP/1.1" 500 - Traceback (most recent call last):

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 2309, in call return self.wsgi_app(environ, start_response)

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 2295, in wsgi_app response = self.handle_exception(e)

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 1741, in handle_exception reraise(exc_type, exc_value, tb)

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask_compat.py", line 35, in reraise raise value

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 2292, in wsgi_app response = self.full_dispatch_request()

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 1815, in full_dispatch_request rv = self.handle_user_exception(e)

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 1718, in handle_user_exception reraise(exc_type, exc_value, tb)

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask_compat.py", line 35, in reraise raise value

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 1813, in full_dispatch_request rv = self.dispatch_request()

File "C:\Users\Steve\PycharmProjects\test\venv\lib\site-packages\flask\app.py", line 1799, in dispatch_request return self.view_functionsrule.endpoint

File "C:\Users\Steve\PycharmProjects\test\venv\hello.py", line 124, in create_factory

'fac_name': request.json['fac_name'],

TypeError: 'NoneType' object is not subscriptable

UPDATE: I changed the if not line into if not request.json: abort(401) and now it is 401 error. And I also tried using Postman and it was the same type of error, so I think this has nothing to do with Android codes and i deleted the Android code from here.

Here's the Postman result:

Answer 1

You are expecting a JSON request

if not request.json or not 'fac_name' in request.json:

But you are sending form-data.

Please check the Radio-Button "raw" and set the content Type to "application/json"

Then you have to add a valid json in your request body.

Answer 2

The error is helpful.

File "C:\Users\Steve\PycharmProjects\test\venv\hello.py", line 124, in create_factory

'fac_name': request.json['fac_name'],

TypeError: 'NoneType' object is not subscriptable

object is not subscriptable

This means you are trying ['keyword'] on an object that does not support it, namely a NoneType.

From which you can deduce request.json is NoneType

Answer 3

Instead of

if not request.json or not 'fac_name' in request.json:
        abort(404)
    factory = {
        'id': factories[-1]['id'] + 1,
        'fac_name': request.json['fac_name'],
        'lat': request.json['lat'],
        'lng': request.json['lng']
    }

I used

    data=request.data
    j_data = json.loads(data)

    factory = {
        'id': factories[-1]['id'] + 1,
        'fac_name': j_data['fac_name'],
        'lat': j_data['lat'],
        'lng': j_data['lng']
    }

And it works. However I have no idea why.