Why do I get AttributeError NoneType object has no attribute something

Question

I keep getting an error that says  AttributeError   NoneType  object has no attribute  something    The code I have is too long to post here  What general scenarios would cause this AttributeError  what is NoneType supposed to mean and how can I narrow down what s going on

User · Answer

Others have explained what NoneType is and a common way of ending up with it  i e   failure to return a value from a function    Another common reason you have None where you don t expect it is assignment of an in-place operation on a mutable object   For example   mylist   mylist sort     The sort   method of a list sorts the list in-place  that is  mylist is modified  But the actual return value of the method is None and not the list sorted  So you ve just assigned None to mylist  If you next try to do  say  mylist append 1  Python will give you this error

User · Answer

The NoneType is the type of the value None    In this case  the variable lifetime has a  value of None   A common way to have this happen is to call a function missing a return   There are an infinite number of other ways to set a variable to None  however

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g d d c  is right  but adding a very frequent example   You might call this function in a recursive form  In that case  you might end up at null pointer or NoneType  In that case  you can get this error  So before accessing an attribute of that parameter check if it s not NoneType

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Consider the code below   def return something someint    if  someint  gt  5      return someint  y   return something 2  y real     This is  going to give you the error      AttributeError   NoneType  object has no attribute  real    So points are as below    In the code  a function or class method is not returning anything  or returning the None  Then you try to access an attribute of that returned object which is None   causing the error message

User · Answer

It means the object you are trying to access None  None is a Null variable in python  This type of error is occure de to your code is something like this   x1   None print x1 something    or  x1   None x1 someother    Hellow world    or x1   None x1 some func      you can avoid some of these error by adding this kind of check if x1 is not None           Do something here else      print  X1 variable is Null or None

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When building a estimator  sklearn   if you forget to return self in the fit function  you get the same error   class ImputeLags BaseEstimator  TransformerMixin       def   init   self  columns           self columns   columns      def fit self  x  y None               do something          def transfrom self  x           return x      AttributeError   NoneType  object has no attribute  transform     Adding return self to the fit function fixes the error

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You can get this error with you have commented out HTML in a Flask application  Here the value for qual date expiry is None       lt  --  lt td gt    qual date expiry date      lt  td gt  -- gt    Delete the line or fix it up    lt td gt    if qual date attained    None       qual date attained date         endif     lt  td gt

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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

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if val is not None      print val  else      pass  check wheather particular data is not empty or null

User · Answer

You have a variable that is equal to None and you re attempting to access an attribute of it called  something   foo   None foo something   1  or foo   None print foo something   Both will yield an AttributeError   NoneType

[python] Why do I get AttributeError: 'NoneType' object has no attribute 'something'?

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