python - self - required positional argument [duplicate]

问题

This question already has answers here:

What is the purpose of the word 'self', in Python? (21 answers)

TypeError: Missing 1 required positional argument: 'self' (5 answers)

Closed last year.

here is my code:

my file which I start:

 from SQLhandler import SQLhandler 
 D = SQLhandler.loadProject(4711)

a part of my SQLhandler file:

class SQLhandler(object):
   db = pymysql.connect(... )

   def loadProject(self, project_id):
    #do some stuff

I want to use db in other functions, so I put it on the class level and added a "self" to loadProject. Now the second line in my start file throws an error:

"loadProject() missing 1 required positional argument: 'project_id'"

What's wrong with my code?

回答1:

Within your class definition you need to have a def __init__(self, ... params): function that tells how to initialize a new instance. Try including something along the lines of

def __init__(self, project_id):
    self.project_id = project_id

来源：https://stackoverflow.com/questions/53218211/python-self-required-positional-argument