关于python：’NoneType’对象不可订阅

'NoneType' object is not subscriptable

本问题已经有最佳答案，请猛点这里访问。

我正在创建一个使用flask+python编写的服务器的iOS应用程序，当我与服务器建立连接以注册用户时，在server.py文件中不断得到"nonetype"对象是不可订阅的错误。基本上，我的问题是什么导致了这个错误，以及我如何修复这个错误。另外，如果有人能给我指出正确的方向，用不同或更简单的方法来做这件事，我会感激的，谢谢！

这是server.py文件：

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import bcrypt
from flask import Flask, request, make_response,jsonify
from flask_restful import Resource, Api
from pymongo import MongoClient
from json import JSONEncoder
from bson.objectid import ObjectId
from functools import wraps

app = Flask(__name__)

mongo = MongoClient('localhost', 27017)

app.db = mongo.eventure_db

app.bcrypt_rounds = 12

api = Api(app)

# Authentication code.
def check_auth(username, password):
# check_auth should access the database and check if the username + password are correct.
# create a collection to hold the users.

user_collection = app.db.users
user = user_collection.find_one({'username': username})

if user is None:
return False
else:
# check if hash generated matches stored hash
encodedPassword = password.encode('utf-8')
if bcrypt.hashpw(encodedPassword, user['password']) == user['password']:
return True
else:
return False

# User resource

class User(Resource):

def post(self):
if (request.json['username'] == None
or request.json['password'] == None):
return ({'error': 'Request requires username and password'},
400,
None)

user_collection = app.db.users
user = user_collection.find_one({'username': request.json['username']})

if user is not None:
return ({'error': 'Username already in use'}, 400, None)
else:
encodedPassword = request.json['password'].encode('utf-8')
hashed = bcrypt.hashpw(
encodedPassword, bcrypt.gensalt(app.bcrypt_rounds))
request.json['password'] = hashed
user_collection.insert_one(request.json)

@requires_auth
def get(self):
return (None, 200, None)

api.add_resource(User, '/eventure/api/v1.1/user/')

# Must define a custom JSON Serializer for flask_restful
# this is because ObjectId is not a string, and therefore,
# Flask's default serializer cannot serialize it.

@api.representation('application/json')
def output_json(data, code, headers=None):

resp = make_response(JSONEncoder().encode(data), code)
resp.headers.extend(headers or {})
return resp

if __name__ == '__main__':
app.config['TRAP_BAD_REQUEST_ERRORS'] = True
app.run(host='localhost', port=8789, debug=True)

这是我在Swift中的注册功能：

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@IBAction func register(_ sender: AnyObject) {

let url = URL(string:"http://localhost:8789/eventure/api/v1.1/user/")

var request = URLRequest(url: url!)

request.httpMethod ="POST"

request.setValue(generateBasicAuthHeader(username: username.text!, password: password.text!), forHTTPHeaderField:"Authorization")

let session = URLSession.shared

let task = session.dataTask(with: request) { data, response, error in
if let response = response, let data = data {
print(String(data: data, encoding: String.Encoding.utf8))
}
}

task.resume()

self.username.text =""
self.password.text =""

}

号

回溯：

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[28/Oct/2016 19:22:33]"POST /eventure/api/v1.1/user/ HTTP/1.1" 500 -
Traceback (most recent call last):
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1836, in __call__
return self.wsgi_app(environ, start_response)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1820, in wsgi_app
response = self.make_response(self.handle_exception(e))
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask_restful/__init__.py", line 270, in error_router
return original_handler(e)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1403, in handle_exception
reraise(exc_type, exc_value, tb)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/_compat.py", line 32, in reraise
raise value.with_traceback(tb)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1817, in wsgi_app
response = self.full_dispatch_request()
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1477, in full_dispatch_request
rv = self.handle_user_exception(e)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask_restful/__init__.py", line 270, in error_router
return original_handler(e)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1381, in handle_user_exception
reraise(exc_type, exc_value, tb)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/_compat.py", line 32, in reraise
raise value.with_traceback(tb)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1475, in full_dispatch_request
rv = self.dispatch_request()
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/app.py", line 1461, in dispatch_request
return self.view_functions[rule.endpoint](**req.view_args)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask_restful/__init__.py", line 471, in wrapper
resp = resource(*args, **kwargs)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask/views.py", line 84, in view
return self.dispatch_request(*args, **kwargs)
File"/Users/Dynee/eventure-backend-api/development/lib/python3.5/site-packages/flask_restful/__init__.py", line 581, in dispatch_request
resp = meth(*args, **kwargs)
File"/Users/Dynee/eventure-backend-api/server.py", line 128, in post
if (request.json['username'] == None
TypeError: 'NoneType' object is not subscriptable

还有generateBasicauthHeader函数：

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func generateBasicAuthHeader(username: String, password: String) -> String {

let loginString = String(format:"%@:%@", username, password)
let loginData = loginString.data(using: String.Encoding.utf8)!
let base64LoginString = loginData.base64EncodedString()
let basicAuthHeader ="Basic \(base64LoginString)"
return basicAuthHeader
}

。