CODEWITHSUNDEEP
pythondjangodjango-modelsuuid
Chad Crowe
Chad Crowe

Reputation: 1338

How to use UUID

I am trying to get unique IDs for my Django objects. In Django 1.8 they have the UUIDField. I am unsure how to use this field in order to generate unique IDs for each object in my model.

Here is what I have for the UUIDField

import uuid
from django.db import models

class MyUUIDModel(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

class Person(models.Model):
    ...
    unique_id = MyUUIDModel()

I can reproduce the id for the UUID model, but everytime I do I get the exact same id. For Example:

person = Person.objects.get(some_field = some_thing)
id = person.unique_id.id

id then gives me the same id every time. What is wrong, how do I fix this?

Upvotes: 76

Views: 115196

Answers (6)

Gata
Gata

Reputation: 463

in model import uuid:

import uuid

in class model use:

class Article(TimeStampedModel):
    uuid = models.UUIDField(editable=False, default=uuid.uuid4, unique=True)
    user = models.ForeignKey(User, on_delete=models.SET_NULL, related_name='articles', null=True)
    categories = models.ManyToManyField(ArticleCategory, blank=True)
    title = models.CharField(max_length=500, null=True, blank=True)
    body = RichTextUploadingField(config_name='portal_lobar_config')
    image = models.ImageField(upload_to='article_images/', null=True, blank=True)
    headline = models.BooleanField(default=True)
    tags = models.ManyToManyField(ArticleTag, blank=True)
    slug = AutoSlugField(max_length=500, populate_from='title', unique_with='created__month', null=True)
    published = models.BooleanField(default=False)
    published_at = models.DateTimeField(null=True, blank=True)

    def __str__(self):
        return self.title

    class Meta:
        ordering = ['-created']

Upvotes: 1

Tom Wojcik
Tom Wojcik

Reputation: 6189

EDIT: Actually I was wrong. It's not possible yet to implement it as DEFAULT_AUTO_FIELD as it has to inherit from IntegerField. Here's the ticket in the django project with feature request to make it possible. Once it's resolved I'll update my answer.

As of Django 3.2, if you want to use uuid as a pk for all your models on a project-wide level, you don't need a generic abstract model anymore. Just define DEFAULT_AUTO_FIELD setting

default value

DEFAULT_AUTO_FIELD = 'django.db.models.AutoField'

so something like this should work

DEFAULT_AUTO_FIELD = 'django.db.models.UUIDField'

Or even better, create your own field.

DEFAULT_AUTO_FIELD = 'project.common.models.CustomUUIDField'

Where you also define uuid type etc.

As seen in the docs, it can also be applied on an app level.

class MyAppConfig(AppConfig):
    default_auto_field = 'project.common.models.CustomUUIDField'

Upvotes: 13

Jatin Goyal
Jatin Goyal

Reputation: 497

To use UUID in Django for a new model see Django Docs.

However, if you want to use it for the existing model (with unique=True) having data corresponding to it, you will not be able to do it directly by the above documentation. It will create migration errors. To do it without losing the data follow all the steps carefully of this Django Documentation.

Upvotes: 2

Sylvestre
Sylvestre

Reputation: 153

You need to use the class you created as a subclass when declaring your Person model like this: 

import uuid
from django.db import models

class MyUUIDModel(models.Model):
  id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

class Person(MyUUIDModel):
  ...

This way Person becomes a subclass of MyUUIDModel and will inherit its id field definition.

Upvotes: 15

Alasdair
Alasdair

Reputation: 309089

I'm not sure why you've created a UUID model. You can add the uuid field directly to the Person model.

class Person(models.Model):
    unique_id = models.UUIDField(default=uuid.uuid4, editable=False, unique=True)

Each person should then have a unique id. If you wanted the uuid to be the primary key, you would do:

class Person(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

Your current code hasn't added a field to the person. It has created a MyUUIDModel instance when you do MyUUIDModel(), and saved it as a class attribute. It doesn't make sense to do that, the MyUUIDModel will be created each time the models.py loads. If you really wanted to use the MyUUIDModel, you could use a ForeignKey. Then each person would link to a different MyUUIDModel instance.

class Person(models.Model):
    ...
    unique_id = models.ForeignKey(MyUUIDModel, unique=True)

However, as I said earlier, the easiest approach is to add the UUID field directly to the person.

Upvotes: 133

Rahul Gupta
Rahul Gupta

Reputation: 47896

You can directly add the id field as a UUIDField in the Person model. There is no need for a separate MyUUIDModel.

I think you have confused it with the MyUUIDModel used in the UUIDField example where the id is a UUIDField. You can just use the below code and it will use UUIDs for id.

import uuid
from django.db import models

class Person(models.Model):
    ...
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

Upvotes: 11

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