field_name = models.Field (null = True)
Django embedded field validation
null = True Explanation
Illustration of null = True using the example. Consider a project named
pythonengineering that has an application named
Refer to the following articles to check how to create a project and an app in Django.
Enter the following code into the
models.py file of the geeks application. We will use CharField to experiment with all the margin variations.
After running makemigrations and migrating to Django and rendering the above model, let’s try creating an instance using None from the Django shell. To start the Django shell, enter the command,
Python manage.py shell
Now let’s try to create a GeeksModel instance using None .
Let’s check in the admin interface to see if the model has been instantiated.
Therefore null = True changes the field to accept values NULL or in terms of Python None Values.
Advanced Concepts with null = True
Avoid empty values in no data ": NULL and empty string . In most cases, it is redundant to have two possible values for "no data"; Django’s convention is to use an empty string, not NULL. The only exception is when the CharField is unique = True and empty = True . In this situation,
null = True is required to avoid unique constraint violations when storing multiple objects with null values.
For both string and non-string fields, you must also set
blank = True if you want to allow blank values in forms, since a null parameter only affects the database storage (see blank).