Python 基于shelve的简单数据库，加值

Question

大家好，我是初学者，我需要为类创建简单的数据库。我正在尝试修改我们收到的示例代码，但有太多的可能性，我迷失了方向。

我的想法是，我可以 add/remove 带有数量和价格的产品。当涉及到修改列表中已有产品的数量时，我被卡住了..

我有以下用于输入和显示列表功能的代码。

def entry():
    global base
    name=raw_input('Name of the product: ')
    quantity=raw_input('Quantity: ')
    price=raw_input('Price per unit: ')     
    if name not in base.keys():    
        base[name]=[int(quantity),int(price)
    print "Saved."
    elif name in base.keys():

第一个问题是给 [name] 一个以上的值，我可以稍后打印，但我认为他们的方式不正确..

.

def articles():
    global base
    print 'List of articles in magazine'.center(50)
    print '-'*50
    print '|'+'name'.center(15)+'|'+'Quantity'.center(15)+'|'+'Price'.center(15)+'|'
    print '-'*50
    for name,quantity in base.items():
        print "|%14s |" % name,'%13s' % quantity[0],'|' '%13s' % quantity[1],'|' </code> ###  When I use here price instead of quantity[1] it shows error.

Answer 1

也许这个例子可以帮助您重构代码？

import shelve

global base
global magazine_base

def load_data():
    global base
    global magazine_base
    magazine_base = shelve.open('magazine_base')
    if magazine_base.has_key('base'):
        base = magazine_base['base']
        if not base:
            base = [{'name': 'Apple', 'price': 10, 'quantity': 1}]  # example one element base
            # base = []  # it can be also just empty list at the beginning                
    else:
        base = [{'name': 'Apple', 'price': 10, 'quantity': 1}]
        # base = []
        magazine_base['base'] = base

def entry():
    global base
    global magazine_base
    load_data()
    name = raw_input('Name of the product: ')
    quantity = raw_input('Quantity: ')
    price = raw_input('Price per unit: ')

    is_new_entry = True

    # entry is element of base list
    for entry in base:
        if name.lower() == entry['name'].lower():  # checking if name already exist in base list
            is_new_entry = False

    if is_new_entry:  # adding new list element
        base += [{
            'name': name, 
            'quantity': int(quantity),
            'price': float(price)
        }]
        magazine_base['base'] = base
        magazine_base.close()
        print 'Saved.'  # confirmation message
    else:
        print 'Element with the name {} already exist!'.format(name)  # error message
        magazine_base.close()


def articles():
    global base
    print 'List of articles in magazine'.center(50)
    print '-'*50
    print '|'+'Name'.center(15)+'|'+'Quantity'.center(15)+'|'+'Price'.center(15)+'|'
    print '-'*50
    for entry in base:
        print "|%14s |" % entry['name'],'%13s' % entry['quantity'],'|' '%14s' % entry['price'],'|'
    print '-'*50

# testing by running functions
entry()
articles()
entry()
articles()

使用 shelve 更新。

已为您检查，它工作正常。

希望对您有所帮助。

Python 基于shelve的简单数据库，加值

Python simple database based on shelve, adding values

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