Python simple database based on shelve, adding values

Question

Hello guys I'm absolute beginner and I need to create simple database for my classes. I'm trying to modify the example code we received but there's so many possibilities and I'm getting lost in it.

The idea is that I can add/remove products with quantities and prices. I get stuck when it comes to modify quantity of product already in the list..

I've got following codes for entry and showing the list functions.

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():

there is first problem of giving a [name] more than 1 value, I can print it later but in they way I think is incorrect..

.

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

Maybe this example will help you in refactoring your code?

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()

Updated with use of shelve.

Checked for you and it is working fine.

Hope this helps.