Consider the following code:
req = { "foo": True }
if req.get("bar").get("baz") != "qux":
print("Not Found")
I expect this to print Not Found, because there is no bar containing a baz containing qux. Instead, it fails with an exception:
AttributeError: 'NoneType' object has no attribute 'get'
How can this be avoided?
If you want to be able to chain .get()s, pass {} as the default for all but the last:
if req.get("result", {}).get("action") != "music.play":
That way if req has no result, the first get() returns {}, which does in turn have a .get() method.
req.get("bar").get("baz") only works if the first get returns a dictionary with the right key
In [182]: req = {'bar': {'baz': 'foo'}}
In [183]: req.get('bar')
Out[183]: {'baz': 'foo'}
In [184]: req.get('bar').get('baz')
Out[184]: 'foo'
That is the second get applies to the object returned by the first.
In [185]: req = { "foo": True }
In [186]: req.get('bar')
# returned None
Another way to write this would be:
req['bar']['baz'] # req must be a nested dictionary
get takes a default, which could be another dictionary. In fact it could return the dictionary itself - repeatedly:
In [187]: req.get('bar', req)
Out[187]: {'foo': True}
In [188]: req.get('bar', req).get('baz')
In [189]: req.get('bar', req).get('baz', req)
Out[189]: {'foo': True}
In [190]: req.get('bar', req).get('baz', req).get('foo')
Out[190]: True
This would return your NotFound:
In [193]: req.get('bar', {}).get('baz', 'fppbar')
Out[193]: 'fppbar'
NoneType means that instead of an instance of whatever Class or Object you think you're working with, you've actually got None. That usually means that an assignment or function call up above failed or returned an unexpected result.
Please refer this answer : https://stackoverflow.com/a/8949265/6332980
This error means that your call to the req.get() function returned None, which means a null reference. Therefore, in that case, you are trying to access the get property of a null reference, which cannot be done.
