如何修改搁置中的数据？

Question

我使用以下代码打开了一个搁置：

#!/usr/bin/python
import shelve                   #Module:Shelve is imported to achieve persistence

Accounts = 0
Victor = {'Name':'Victor Hughes','Email':'victor@yahoo.com','Deposit':65000,'Accno':'SA456178','Acctype':'Savings'}
Beverly = {'Name':'Beverly Dsilva','Email':'bevd@hotmail.com','Deposit':23000,'Accno':'CA432178','Acctype':'Current'}

def open_shelf(name='shelfile.shl'):
    global Accounts
    Accounts = shelve.open(name)          #Accounts = {}
    Accounts['Beverly']= Beverly    
    Accounts['Victor']= Victor


def close_shelf():
    Accounts.close()

我能够将值附加到搁置中，但无法修改这些值。我定义了一个函数shelve.But ()，我想从它修改shelve.But中的数据，它给了我以下错误：

Traceback (most recent call last):
  File "./functest.py", line 16, in <module>
    Deposit()
  File "/home/pavitar/Software-Development/Python/Banking/Snippets/Depositfunc.py", line 18, in Deposit
    for key in Accounts:
TypeError: 'int' object is not iterable

这里是我的函数：

#!/usr/bin/python

import os                       #This module is imported so as to use clear function in the while-loop
from DB import *                       #Imports the data from database DB.py

def Deposit():
        while True:
                os.system("clear")              #Clears the screen once the loop is re-invoked
                input = raw_input('\nEnter the A/c type: ')
                flag=0
                for key in Accounts:
                        if Accounts[key]['Acctype'].find(input) != -1:
                                amt = input('\nAmount of Deposit: ')
                                flag+=1
                                Accounts[key]['Deposit'] += amt

                if flag == 0:
                        print "NO such Account!"    

if __name__ == '__main__':
        open_shelf()
        Deposit()
        close_shelf()

如果我错了，我是Python.Please help.Correct me的新手，我需要有人来解释一下这个代码的功能，我很困惑。

Answer 1

首先，不要为Accounts使用全局，而是来回传递它。使用全局导致您的错误。如下所示：

def open_shelf(name='shelfile.shl'):
    Accounts = shelve.open(name)          #Accounts = {}
    ...
    return Accounts

def close_shelf(Accounts):
    Accounts.close()


def Deposit(Accounts):
    ...   

if __name__ == '__main__':
    Accounts = open_shelf()
    Deposit(Accounts)
    close_shelf(Accounts)

第二，不要重新定义内置函数。在Deposit()中，将raw_input的结果赋值给一个名为input的变量

input = raw_input('\nEnter the A/c type: ')

四行之后，您尝试使用内置的input函数：

amt = input('\nAmount of Deposit: ')

但是这是行不通的，因为input已经被重新定义了！

第三，当迭代被搁置的项目时，遵循以下模式: 1)抓取搁置项目；2)变异项目；3)将突变项写回货架。就像这样：

for key, acct in Accounts.iteritems():  # grab a shelved item
    if val['Acctype'].find(input) != -1:
        amt = input('\nAmount of Deposit: ')
        flag+=1
        acct['Deposit'] += amt          # mutate the item
        Accounts[key] = acct            # write item back to shelf

(这第三条建议是从hughdbrown的回答中提炼出来的。)

Answer 2

我想你会有更多这样的运气

for key, val in Accounts.iteritems():
    if val['Acctype'].find(input) != -1:
        amt = input('\nAmount of Deposit: ')
        flag+=1
        val['Deposit'] += amt
        Accounts[key] = val