AttributeError - type object 'Services' has no attribute 'service_price'

Question

I'm trying to create something like an invoice program, to create invoices and calculate prices.

I am still on the models part and I am trying to calculate all the services includes in a single invoice and update them in Invoices.subtotal.

My problem is that I cannot pass the summary value of Services.service_price to Invoices.subtotal.

When I click [Save and Continue editing] I see this:

AttributeError at /admin/invoices/invoices/1/

type object 'Services' has no attribute 'service_price'

Request Method:  POST
Request URL:  http://192.168.1.3/invmaster/admin/invoices/invoices/1/
Django Version:  1.2.1
Exception Type:  AttributeError
Exception Value:  

type object 'Services' has no attribute 'service_price'

Exception Location:  /opt/invmaster/invoices/models.py in save, line 24
Python Executable:  /usr/bin/python
Python Version:  2.6.5

Here is some code:

invoices/models.py

  1 from django.db import models
  2 
  3 from invmaster.general.models import Client
  4 from invmaster.general.models import job_name
  5 from invmaster.general.models import my_data
  6 
  7 from decimal import *
  8 import math
  9 
 10 ### Invoices table
 11 class Invoices (models.Model):
 12         invoice_id = models.AutoField(primary_key=True)
 13         client_name = models.ForeignKey(Client)
 14         date_created = models.DateField()
 15         subtotal = models.DecimalField('Precio sin IVA:(euros)',max_digits=6, decimal_places=2)
 16         total =  models.DecimalField('Precio Final:(euros)',max_digits=6, decimal_places=2, blank=True, null=True)
 17         paid = models.BooleanField()
 18         class Meta:
 19                 db_table = u'invInvoices'
 20 
 21         def save(self, *args, **kwargs):
 22                 #self.subtotal = int(Services.service_price)
 23                 f = my_data()
 24                 self.subtotal = Services.service_price
 25                 self.total = self.subtotal * ((Decimal(f.IVA)/100)+1)
 26                 super(Invoices, self).save(*args, **kwargs)
 27
 28 
 29 
 30 ### Services table
 31 class Services (models.Model):
 32         JOB_CUANTITY = ( (u'H',u'Horas'),
 33                         (u'U',u'Unidades'),
 34                         )
 35         invoice_id = models.ForeignKey(Invoices)
 36         service_type = models.CharField('Tipo',max_length=1, choices=JOB_CUANTITY)
 37         service_cuantity = models.IntegerField('Cantidad/Horas', max_length=2)
 38         service_name = models.ForeignKey(job_name)
 39         service_unit_price = models.DecimalField('Precio por unidad (euros):',max_digits=6, decimal_places=2,blank=True, null=True)
 40         service_price = models.DecimalField('Precio (euros):',max_digits=6, decimal_places=2, blank=True, null=True)
 41 
 42         class Meta:
 43                 db_table = u'invServices'
 44         def __unicode__(self):
 45                 return u'%s' % (self.service_name)
 46         def save(self, *args, **kwargs):
 47                 self.service_price = self.service_cuantity * self.service_unit_price
 48                 super(Services, self).save(*args, **kwargs)

other files: general/models.py

### General table
  8 class my_data (models.Model):
...
 16         IVA = models.IntegerField(max_length=2, default='18') ### IVA = VAT # 18 = 18%
...
 26 ### Clients table
 27 class Client (models.Model):
 28         client_id = models.AutoField(primary_key=True)
 29         client_name = models.CharField(max_length=45, unique=True)
...
### Jobs
 58 class job_name (models.Model):
 59         job_type_id = models.AutoField(primary_key=True)
 60         job_name = models.CharField('Servicio/Producto',max_length=60, unique=True)
 61         job_price = models.DecimalField('Precio sin IVA (euros:)', max_digits=6, decimal_places=2)
 62 
 63         class Meta:
 64                 db_table = u'genJobNames'
 65 
 66         def __unicode__(self):
 67                 return u'%s (%s)' % (self.job_name, self.job_price)

Sorry for my English and for the question if it is stupid (I'm not a programmer, I'm a sysadmin, and I'm new in python/django :-) )

Thanks in advance

Cheers

UPDATE:

files:

linadmin.homeunix.net/models.txt
linadmin.homeunix.net/admin.txt

Answer 1

You haven't got a summary value anywhere. Services.service_price makes no sense in this context - it's a reference to the model field itself, at the class level, rather than to the value of any particular instance of it.

You need some code to calculate the actual value. Bear in mind that you have a ForeignKey from Services to Invoices, which means that each invoice can have many services. So presumably what you want is the total value of all services related to this invoice. You can work this out using an aggregation:

from django.db.models import Sum
service_sum = self.services_set.aggregate(Sum('service_price'))
self.subtotal = service_sum['service_price__sum']

which does a SUM query against the database for all related services.