Signal post_save in Django and models - django

Question

I have function with signal:
#receiver(post_save, sender=Task)
def my_handler():
executor = User.objects.filter(user_type='Executer')
executor.balance += Task.money
executor.save()
My function should add money to executor after task added. But it gives mistake like:
Internal Server Error: /api/v1/tasks/
Traceback (most recent call last):
...
File "/home/k/pro/freelance-django/free/lib/python3.5/site-packages/django/db/models/fields/__init__.py", line 1853, in get_prep_value
return int(value)
ValueError: invalid literal for int() with base 10: 'Executer'
[20/Sep/2017 14:00:30] "POST /api/v1/tasks/ HTTP/1.1" 500 188088
User class looks like:
from __future__ import unicode_literals
from django.db import models
from django.contrib.auth.models import AbstractUser
class User(AbstractUser):
CUSTOMER = 1
EXECUTER = 2
USER_TYPES = (
(CUSTOMER, 'Customer'),
(EXECUTER, 'Executer'),
)
user_type = models.IntegerField(choices=USER_TYPES, default=EXECUTER, verbose_name='Тип пользователя')
balance = models.DecimalField(decimal_places=2, max_digits=7, default=0, verbose_name='Баланс')
def __str__(self):
return self.username
Task class from task.models is:
class Task(models.Model):
title = models.CharField(max_length=255, verbose_name='Заголовок')
description = models.CharField(max_length=255, verbose_name='Описание')
money = models.DecimalField(max_digits=7, decimal_places=2, default=0, verbose_name='Цена')
assignee = models.ForeignKey('users.User', related_name='assignee', null=True, verbose_name='Исполнитель')
created_by = models.ForeignKey('users.User', related_name='created_by', verbose_name='Кем был создан')
How should I make it work?

Answer 1

U don't have one object but objects so you need literal on them or do update(). The best option is use F expression which has a good performance because its executed on DB:
from django.db.models import F
#receiver(post_save, sender=Task)
def my_handler(sender, instance, **kwargs):
User.objects.filter(user_type=User.EXECUTER).update(balance=F('balance') + instance.money)
This update all records where user_type is Executer and update them balance in one query.
Django docs update
F expressions
Your user_type field is IntegerField and in your choices you have string value so u need change it to something like this:
class User(AbstractUser):
CUSTOMER = 1
EXECUTER = 2
USER_TYPES = (
(CUSTOMER, 'Customer'),
(EXECUTER, 'Executer'),
)
user_type = models.IntegerField(choices=USER_TYPES, default=EXECUTER, verbose_name='Тип пользователя')
balance = models.DecimalField(decimal_places=2, max_digits=7, default=0, verbose_name='Баланс')