试图将类的实例传递给另一个fi

Question

我试图从另一个文件中调用我的类文件，实例化对象（有效），然后启动第二个文件中的一个函数（无效）。你知道吗

当我尝试调用第二个文件中的一个函数时，出现了一个错误。我想我理解为什么会这样，因为实例是在文件1中创建的，而文件1没有访问 方法（创建\u帐户）。但有什么办法吗？你知道吗

如果我在第二个文件中添加类定义，我可以让它工作。但我想如果我把它们放在第一个文件里，我的设计会更好

例如，错误是-

Traceback (most recent call last):
  File "C:\Users\hassy\Google Drive\Python\bnk\bank_account\database.py", line 130, in <module>
    obj1.Database.create_account("Frank Sanchez", 135063543, 2380, 100, 'bank_account')
AttributeError: 'BankAccount' object has no attribute 'Database'

---

class BankAccount:
    def __init__(self, name, social, account_number, balance, acctype):
        self.name = name
        self.social = social
        self.account_number = account_number
        self.balance = balance
        self.acctype = acctype


class CreditCard(BankAccount):
    def __init__(self, name, social, account_number, balance, acctype, card_no, credit_score=None, credit_limit=None):
        super().__init__(name, social, account_number, balance, acctype)
        self.card_no = card_no
        self.credit_score = credit_score
        self.credit_limit = credit_limit

class SavingsAccount(BankAccount):
    def __init__(self, name, social, account_number, balance, acctype, rate=None):
        super().__init__(name, social, account_number, balance, acctype)
        self.rate = None

数据库文件（第二个文件）-

import sqlite3
import secrets
import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.base import MIMEBase
from email import encoders
import send_email
#import account
from account import BankAccount
from account import CreditCard

conn = sqlite3.connect('bank_account.db')
c = conn.cursor()



def create_account(self, name, social, account_number, balance, acctype, card_no=None, credit_score=None, credit_limit=None):
    """ create different accounts based on account type passed in """

    with conn:

        if acctype == 'bank_account':
            c.execute("INSERT INTO {} VALUES (:name, :social, :account_number, :balance, :pin)".format(acctype),
                      {'name':name, 'social': social,'account_number': account_number, 'balance':balance, 'pin':''})
            print("New account: {} has been created, acc # is: {}".format(acctype, account_number))

        elif acctype == 'savings_account':
            c.execute("INSERT INTO {} VALUES (:name, :social, :account_number, :balance, :rate)".format(acctype),
                  {'name':name, 'social': social,'account_number': account_number, 'balance':balance, 'rate':''})
            print("New account: {} has been created, acc # is: {}".format(acctype, account_number))

        elif acctype == 'credit_card':
            c.execute("INSERT INTO credit_card VALUES (:name, :social, :account_number, :balance, :card_no,:credit_score, :credit_limit, :pin)",
              {'name':name, 'social': social,'account_number': account_number, 'balance':balance, 'card_no'
               :card_no, 'credit_score':credit_score, 'credit_limit':credit_limit, 'pin':'' })
            print("New account: {} has been created, acc # is: {}".format(acctype, account_number))
    conn.commit()

def get_account(self,account_number, acctype):
    """ Show all rows in DB for the the account type passed in """
    with conn:
        account_find = c.execute("SELECT * from {} WHERE account_number=:account_number".format(acctype),
                                 {'account_number':account_number})
        account_found = c.fetchone()
        if not account_found:
            print("No {} matching that number could be found".format(acctype))
        else:
            print("Account type: {} exists!".format(acctype))
            print(account_found)
    return(account_found)

def get_balance(self, account_number, acctype):
    """ get balance from account """
    with conn:
        balance = c.execute("SELECT balance from {} WHERE account_number=:account_number".format(acctype),
                            {'account_number':account_number})
        balance = c.fetchone()
        print("The balance for account number: {} is ${}".format(account_number, balance[0]))
        notif_set = BankAccount.get_notif(self, account_number, acctype)
        if notif_set is None:
            print("No notifications are set for this user")
        else:
            notif_balance = notif_set[4]
            name = notif_set[0]
            if notif_balance == 1:
                notify = send_email.send_email(account_number, acctype, 'Balance', balance, balance, name)

    return(balance[0])


def deposit(self, account_number, acctype, amount):
    """ Deposit funds into the account number + acctype for the account passed in """
    with conn:

        account_found = BankAccount.get_account(self, account_number, acctype)
        if account_found:
            existing_bal = account_found[3]
            c.execute("""UPDATE {} SET balance=balance +:amount
                    WHERE account_number =:account_number""".format(acctype),
                      {'account_number':account_number, 'amount':amount})
            new_bal = existing_bal + (int(amount))
            print("${} has been deposited to account {} and the new balance is ${}".format(amount, account_number, existing_bal + (int(amount))))

           # Check email configurations are turned on for deposits
            notif_set = notifications.get_notif(self, account_number, acctype)
            if notif_set is None:
                print("No notifications are set for this user")
            else:
                notif_deposits = notif_set[5]
                name = notif_set[0]
                if notif_deposits == 1:
                    notify = send_email.send_email(account_number, acctype, 'Deposit', amount, new_bal, name)


def withdraw(self, account_number, acctype, amount):
    """ withdraw funds from the bank account number passed in """
    with conn:

        account_found = BankAccount.get_account(self, account_number, acctype)
        existing_bal = account_found[3]

        if account_found:
            c.execute("""UPDATE bank_account SET balance=balance -:amount
                    WHERE account_number =:account_number""",
                      {'account_number':account_number, 'amount':amount})
            new_bal = existing_bal - (int(amount))
            conn.commit()
            print("${} has been withdrawn from account {} and the new balance is ${}".format(amount, account_number, existing_bal - (int(amount))))

            notif_set = BankAccount.get_notif(self, account_number, acctype)
            if notif_set is None:
                print("No notifications have been set for this acct")
            else:
                notif_withdraw = notif_set[7]
                name = notif_set[0]
                if notif_withdraw == 1:
                    notify = send_email.send_email(account_number, acctype, 'Withdraw', amount, new_bal, name)
        else:
            print("Withdrawl notifications have been turned off")
        if account_found and new_bal < 0 and notif_set is not None:
            notify_o = send_email.send_email(account_number, acctype, 'Overdraft', amount, new_bal, name)
        conn.commit()


if __name__ == '__main__':
    obj1 = BankAccount("Frank Sanchez", 135063543, 2380, 100, 'bank_account')
    obj1.Database.create_account("Frank Sanchez", 135063543, 2380, 100, 'bank_account')

Answer 1

 I think I understand why that happens, as the instance was created in file 1, and that file 1 doesnt have access to the method from the second file (create_account).

这并不是问题所在，不是因为实例在另一个文件中，所以它没有访问该方法的权限，而是因为该方法是为不同的类定义的。你知道吗

编写obj1 = BankAccount()时，将对BankAccount实例的引用放入变量obj1。然后在编写obj1.Database. ...时，Python尝试从obj1访问名为Database的方法，即BankAccount。由于没有在文件1中的BankAccount类上定义名为Database的方法，因此会抛出错误。你知道吗

如果您想在不同类的实例之间创建交互，您需要以某种方式“连接”它们。通常，这是通过将对象A的实例传递给在不同对象B的实例上调用的方法来实现的，或者通过在对象B的方法内显式创建对象A的实例来实现的。考虑这个示例，它显示了：

class Account:
    pass

class Database:
    def __init__(self):
        self.accounts = []

    def add_account(self, acc):
        if not isinstance(acc, Account):
            raise TypeError("bad input")
        self.accounts.append(acc)

    def create_default_account(self)
        default_account = Account()
        self.accounts.append(default_account)

account = Account()
db = Database()

# passes an Account object as an argument to 
# a Database object method call
db.add_account(account)

# calls a Database object method which internally 
# creates and processes an Account object
db.create_default_account()        

请注意，这个示例代码是在单个文件上编写的，但是只要正确地完成了相应的导入，它在两个单独的文件上也能正常工作。你知道吗