CODEWITHSUNDEEP
pythondjangodjango-modelsforeign-keysdjango-views
Jamgreen
Jamgreen

Reputation: 11039

Django field refering to another field

I'm about to make a Django model with conditions. I've thought about these fields

class Condition(models.Model):
    model_name = CharField(max_length=100)
    field_name = CharField(max_length=100)
    value = CharField(max_length=100)

So I can create a condition where a specific field (field_name) in a specific model (model_name) is equal to value. But I thought there might be a solution for this already? Instead of using field_name I thought if it was possible to refer directly to the field either through ContentType or something else?

Upvotes: 1

Views: 98

Answers (2)

Brian Artschwager
Brian Artschwager

Reputation: 279

I know this is very high level and the code does not exactly model what you were asking. But they are simple examples from a

Django Signals to determine when a change happened. https://docs.djangoproject.com/en/dev/topics/signals/

Here is a signals.py file in my app for managing Person objects when Users change:

from django.db import models
from anotherapp.models import *

def user_post_delete(sender, instance, **kwargs):
    try:
        if instance.username:
            person_item = Person.objects.get(username = instance.username)
            person_item.django_user = None
            person_item.save()
    except:
        pass

def user_post_save(sender, instance, **kwargs):
    try:
        if instance.username:
            p, created = Person.objects.get_or_create(
                username=instance.username)
            p.django_user = instance
            p.save()
    except:
        pass

models.signals.post_delete.connect(user_post_delete, sender=User)
models.signals.post_save.connect(user_post_save, sender=User)

Django ContentTypes to relate your condition to the object in question. https://docs.djangoproject.com/en/dev/ref/contrib/contenttypes/

Here is an model I am using with ContentTypes:

from django.contrib.contenttypes.models import ContentType
class Comment(models.Model):
    message = models.TextField()
    #removed fields not relevent
    content_type = models.ForeignKey(ContentType)
    object_id = models.PositiveIntegerField()
    content_object = generic.GenericForeignKey('content_type', 'object_id')
    date_added = models.DateTimeField('date_added',auto_now_add=True, editable=False)
    date_updated = models.DateTimeField('date_updated',auto_now_add=True, auto_now=True, editable=False)

Then in your views.py/signals.py to use that ContentType model(Ticket is a model name, and t.id is the id of the Ticket object:

new_comment = Comment(
    message = "test message",
    content_type = ContentType.objects.get(model='Ticket'),
    object_id = t.id,
)
new_comment.save()

You would then want to expand to have a simple boolean as to if your condition was met, or get a bit more into it and use another model to store results and come up with a "5

Upvotes: 1

mrlnt
mrlnt

Reputation: 1

You can refer to Django's models.ForeignKey doc.

Upvotes: 0

Related Questions