Open a file while using classes/modules-CodePudding

I am trying to create a bank account program and I need to save a file with all the transactions that the user does. I'm trying to use classes and it's not working for me. someone can help or give a better solution?

class BankAccount():
def __init__(self, first_name, last_name, personal_number,currency, amount = 0):
    self.first_name = first_name
    self.last_name = last_name
    self.personal_number = personal_number
    self.currency = currency
    self.amount = amount
    self.the_file = open("{self.personal_number}.txt", "a")
    self.the_file.write("{self.first_name} {self.last_name} {self.personal_number}\n In the bank {self.amount} {self.currency}")
    print(self.the_file.readlines())


anton = BankAccount("anton", "james", "123456789", "$", 15)

CodePudding user response：

You can't read this file because you opened it on append mode. To read and append to the file you have to open it with the a mode.

myFile = open("myfile.txt", "a ")
myFile.seek(0)

print(myFile.read())

The myFile.seek(0) must be called because when opening with append mode the "file cursor" is automatically at the end

CodePudding user response：

You are opening the file in append mode, which means "write at the end of the file"). So reading is invalid. You should open the file in read&write mode for your code to work. which would be:

self.the_file = open(f"{self.personal_number}.txt", "w ") # "r " also works

Also mind you aren't using format string properly, make sure to have a f before the quotes.

This will solve your problem, however you will have bad time reading your data from those files. You should serialize your data (pickle, json, csv...).