Python 3 AttributeError even though attribute exists

问题

I have a set of python files which make up a program for saving tidbits of info and searching them via tag association. I had the program working for many versions, but I recently made what I thought was a minor change that caused the program to go haywire. The ENTRY object is the basis of the data storage - it holds a unique ID number, a nickname, a value, and a list of tags.

class ENTRY:

def __init__(self, idNum, nickName, value, tagList):
    self.idNum = idNum
    self.nickName = nickName
    self.value = value
    self.tagList = tagList

I realized that I was interchangeably referring to the "nickName" attribute as "name" when asking for input in other files, so I decided to Find and Replace all mentions of "nickName" with "name" to make the code easier to follow. I did this in the ENTRY.py file as well as all of the associated python files in the program. I even proofread them to make sure the change did not mess with any case-sensitive function calls or anything.

The problem: Now, when I run the program, I get an attribute error:

Traceback (most recent call last):
  File "/Memory/TagMem.py", line 210, in <module>
    main()
  File "/Memory/TagMem.py", line 207, in main
    dispatch(userChoice)
  File "/Memory/TagMem.py", line 171, in dispatch
    nameList('todo')
  File "/Memory/TagMem.py", line 103, in nameList
    memory.searchListNames(queryList)
  File "/Memory/Memory.py", line 96, in searchListNames
    each.printName()
  File "/Memory/ENTRY.py", line 49, in printName
    print("({}) {}".format(self.idNum, self.name))
AttributeError: 'ENTRY' object has no attribute 'name'

But after the Find and Replace, the ENTRY object most certainly has an attribute 'name':

class ENTRY:

def __init__(self, idNum, name, value, tagList):
    self.idNum = idNum
    self.name = name
    self.value = value
    self.tagList = tagList

Does anyone know of a reason I would get an attribute error when the attribute is very clearly defined in the class constructor?

For more complete information on the full class code, see the github repository: https://github.com/kylelambert101/TagMem

And the specific commit with the crash-inducing changes: https://github.com/kylelambert101/TagMem/commit/68987f2e6ed98012f36ec5230b3dac6f09373489

Thank you!

回答1:

I figured out where I went wrong! My program is associated with a file called myMemory.dat which stores a pickled version of a Memory object and is loaded and saved with each run of the program. The Memory object is essentially a list of ENTRYs to be queried. At the time when I updated all of my code to use the name name instead of nickname, I already had hundreds of ENTRY objects saved in myMemory.dat - each an instance of the old ENTRY object with a nickName attribute instead of a name attribute. When I called functions which attempted to access the ENTRY object's name attribute, the program threw an error because the ENTRY objects in question did not have that attribute.

The fix: I looped through the Memory object stored in myMemory.dat and copied all of the info into new ENTRYs in a new Memory object. I saved the new Memory to myMemory.dat, and the program works good as new!

来源：https://stackoverflow.com/questions/38018475/python-3-attributeerror-even-though-attribute-exists

标签

python

replace

attributes

find

attributeerror