CODEWITHSUNDEEP
pythondjangodjango-modelsdjango-signals
M. Gar
M. Gar

Reputation: 887

Use a signal to update different tables

I have the members, colors, groups, members_colors, members_groups and colors_groups tables. The members, colors, groups and colors_groups tables alredy have the needed registers but I need that when a register is added to the members_groups table automatically check the colors asigned for that group and then add registers to the members_colors table with the member especified in members_groups table and the colors asigned for the group that the member belongs.

I think to do that with a post_save signal using members_groups as sender but I cannot figure how.

EDIT: I use the default User model from django and this is my models.py file:

class Colors(models.Model):
    name = models.CharField(max_length=50)

class Groups(models.Model):
    name = models.CharField(max_length=100)

class Groups_Colors(models.Model):
    group = models.ForeignKey(Groups, related_name='gc_group', null=True, blank=True)
    color = models.ForeignKey(Colors, related_name='gc_color', null=True, blank=True)

class Users_Colors(models.Model):
    user = models.ForeignKey(User, related_name='uc_user', null=True, blank=True)
    color = models.ForeignKey(Colors, related_name='uc_color', null=True, blank=True)

class Groups_Users(models.Model):
    group = models.ForeignKey(Groups, related_name='gu_group', null=True, blank=True)
    user = models.ForeignKey(User, related_name='gu_user', null=True, blank=True)

What I want is when a register in Groups_Users is added, automatically update the Users_Colors table using as reference the data in Groups_Users to take the values from Groups_Colors and User.

EDIT 2 Thanks to @ilse2005 I can get the signal work like I want. Here's the signal if someone need something alike:

@receiver(post_save, sender=Groups_Users, dispatch_uid='signal_receiver') 
def signal_receiver(sender, instance, **kwargs):
    group = instance.group
    user = instance.user
    colors = Groups_Colors.objects.filter(group_id=group).values_list('color_id',flat=True)
    for color in colors:
        Users_Colors.objects.create(user_id=user, color_id = color)

Upvotes: 3

Views: 861

Answers (1)

ilse2005
ilse2005

Reputation: 11439

You can use the post_save Signal. Add this to your models.py:

from django.db.models.signals import post_save
from django.dispatch import receiver

#sender is the Model after which save method the signal is called
@receiver(post_save, sender=Groups_Users) 
def signal_receiver(sender, instance, created, **kwargs):
    # instance is the new GroupUsers
    group = instance.group
    user = instance.user
    # loop over Group_colors and create User_Colors
    for color in group.gc_color.all():
        Users_Colors.objects.create(user=user, color.color)

Upvotes: 2

Related Questions