UUIDField – Django Models
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 uuid
from django.db import models
class MyUUIDModel(models.Model):
id = models.UUIDField(
primary_key = True ,
default = uuid.uuid4,
editable = False )
|
Syntax
field_name = models.UUIDField(**options)
Django Model UUIDField Explanation
Illustration of UUIDField using an Example. Consider a project named geeksforgeeks
having an app named geeks
.
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 geeks app.
from django.db import models
from django.db.models import Model
class GeeksModel(Model):
geeks_field = models.UUIDField()
|
Add the geeks app to INSTALLED_APPS
INSTALLED_APPS = [
'django.contrib.admin' ,
'django.contrib.auth' ,
'django.contrib.contenttypes' ,
'django.contrib.sessions' ,
'django.contrib.messages' ,
'django.contrib.staticfiles' ,
'geeks' ,
]
|
Now when we run makemigrations
command from the terminal,
Python manage.py makemigrations
A new folder named migrations would be created in geeks
directory with a file named 0001_initial.py
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'
)),
( 'geeks_field' ,
models.UUIDField()
)),
],
),
]
|
Thus, an geeks_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.
from geeks.models import GeeksModel
import uuid
test = uuid.uuid4()
geek_object = GeeksModel.objects.create(geeks_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.
|
Last Updated :
12 Feb, 2020
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