UUIDField is a special field to store universally unique identifiers. It uses Python’s UUID class. UUID, Universal Unique Identifier, is a python library that helps in generating random objects of 128 bits as ids. It provides the uniqueness as it generates ids on the basis of time, Computer hardware (MAC etc.). Universally unique identifiers are a good alternative to AutoField for primary_key. The database will not generate the UUID for you, so it is recommended to use default.
For example,
import uuidfrom django.db import models class MyUUIDModel(models.Model): id = models.UUIDField( primary_key = True, default = uuid.uuid4, editable = False) # other fields |
Syntax
field_name = models.UUIDField(**options)
Django Model UUIDField Explanation
Illustration of UUIDField using an Example. Consider a project named neveropen having an app named Lazyroar.
Refer to the following articles to check how to create a project and an app in Django.
Enter the following code into models.py file of Lazyroar app.
from django.db import modelsfrom django.db.models import Model# Create your models here. class GeeksModel(Model): Lazyroar_field = models.UUIDField() |
Add the Lazyroar app to INSTALLED_APPS
# Application definition INSTALLED_APPS = [ 'django.contrib.admin', 'django.contrib.auth', 'django.contrib.contenttypes', 'django.contrib.sessions', 'django.contrib.messages', 'django.contrib.staticfiles', 'Lazyroar',] |
Now when we run makemigrations command from the terminal,
Python manage.py makemigrations
A new folder named migrations would be created in Lazyroar directory with a file named 0001_initial.py
# Generated by Django 2.2.5 on 2019-09-25 06:00 from django.db import migrations, models class Migration(migrations.Migration): initial = True dependencies = [ ] operations = [ migrations.CreateModel( name ='GeeksModel', fields =[ ('id', models.AutoField(auto_created = True, primary_key = True, serialize = False, verbose_name ='ID' )), ('Lazyroar_field', models.UUIDField() )), ], ), ] |
Thus, an Lazyroar_field UUIDField is created when you run makemigrations on the project.It is a field to store python’s UUID instance.
How to use UUIDField ?
UUID, Universal Unique Identifier, is a python library which helps in generating random objects of 128 bits as ids. To know more about UUID visit Generating Random id’s using UUID in Python. Let’s try to save a uuid object into the UUIDField.
# importing the model# from Lazyroar appfrom Lazyroar.models import GeeksModel # importing uuidimport uuid # creating an instance of# uuid objecttest = uuid.uuid4() # creating a instance of # GeeksModelgeek_object = GeeksModel.objects.create(Lazyroar_field = test)geek_object.save() |
Now let’s check it in admin server. We have created an instance of GeeksModel
Field Options
Field Options are the arguments given to each field for applying some constraint or imparting a particular characteristic to a particular Field. For example, adding an argument null = True to UUIDField will enable it to store empty values for that table in relational database.
Here are the option and attributes that an UUIDField can use.
| Field Options | Description |
|---|---|
| Null | If True, Django will store empty values as NULL in the database. Default is False. |
| Blank | If True, the field is allowed to be blank. Default is False. |
| db_column | The name of the database column to use for this field. If this isn’t given, Django will use the field’s name. |
| Default | The default value for the field. This can be a value or a callable object. If callable it will be called every time a new object is created. |
| help_text | Extra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form. |
| primary_key | If True, this field is the primary key for the model. |
| editable | If False, the field will not be displayed in the admin or any other ModelForm. They are also skipped during model validation. Default is True. |
| error_messages | The error_messages argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override. |
| help_text | Extra “help” text to be displayed with the form widget. It’s useful for documentation even if your field isn’t used on a form. |
| verbose_name | A human-readable name for the field. If the verbose name isn’t given, Django will automatically create it using the field’s attribute name, converting underscores to spaces. |
| validators | A list of validators to run for this field. See the validators documentation for more information. |
| Unique | If True, this field must be unique throughout the table. |
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