TypeError: list object is not an iterator [duplicate]

Question

Am trying to make a simple post api in flask-python but am getting this error :

TypeError: list object is not an iterator

but when i revise my code seems fine what could be the problem.

My function which specifically has the problem:

def post(self,name):
        #return {'message': name}
        item = next(filter(lambda x: x['name'] == name, items), None)
        if item:
            return {'message':"An item with name '{}' already exixts. ".format(name)},400
        data = request.get_json()
        item = {'name': name, 'price':data['price']}
        items.append(item)
        return item, 201

When i try to post something on postman i get this logcat error:

[2018-06-07 10:41:02,849] ERROR in app: Exception on /item/test [POST]
Traceback (most recent call last):
  File "C:\Python27\lib\site-packages\flask\app.py", line 1612, in full_dispatch_request
    rv = self.dispatch_request()
  File "C:\Python27\lib\site-packages\flask\app.py", line 1598, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "C:\Python27\lib\site-packages\flask_restful\__init__.py", line 480, in wrapper
    resp = resource(*args, **kwargs)
  File "C:\Python27\lib\site-packages\flask\views.py", line 84, in view
    return self.dispatch_request(*args, **kwargs)
  File "C:\Python27\lib\site-packages\flask_restful\__init__.py", line 595, in dispatch_request
    resp = meth(*args, **kwargs)
  File "G:\flask_workspace\MealBookingApp\MealBookingApp\MealBookingApp\views.py", line 30, in post
    item = next(filter(lambda x: x['name'] == name, items), None)
TypeError: list object is not an iterator
127.0.0.1 - - [07/Jun/2018 10:41:02] "POST /item/test HTTP/1.1" 500 -

NB:

line 30 , is the line below :

item = next(filter(lambda x: x['name'] == name, items), None)

Answer 1

Try using iter()

Ex:

item = next(iter(filter(lambda x: x['name'] == name, items)), None)

Answer 2

To elaborate on @Rakesh's answer, lists aren't iterators, and the output of filter() in Python 2 is a list. To fix this, you can use the iter() function to output an iterator corresponding to the problematic list so that next() can be called appropriately. The same code then should solve your problem:

item = next(iter(filter(lambda x: x['name'] == name, items)), None)

Note that using iter() on an iterator still works in Python 3, so this code is forward compatible.