# Django null=True vs blank=True Field Options Explained

> Use blank=True for form-level validation and null=True for database-level NULL values in Django model fields, with CharField and TextField as exceptions

**URL:** https://sentry.io/answers/django-difference-between-null-and-blank/

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## The Problem

What is the difference between `null=True` and `blank=True` in Django Model Fields?

## The Solution

The fundamental difference between these two is that `null` controls the validation at the database level, and `blank` is used during form field validation at the application level.

Consider the following model with a title field, a date field, and a time field:

```python
from django.db import models

class Book(models.Model):
  title = models.CharField(max_length=200)
  pub_date = models.DateField()
  pub_time = models.TimeField()
```

**By default all fields are required.** In order to make a field optional, we have to say so explicitly.

If we want to make the `pub_time` field optional, we add `blank=True` to the model, which tells Django's field validation that `pub_time` can be empty.

```python
pub_time = models.TimeField(blank=True)
```

But adding `blank=True` to the model is not enough. Trying to submit a form based on the model above will result in an integrity error because, while the field validation will accept an empty response, the database will not accept a null value. 

To inform our database that the column for this field can be left empty (i.e. null), we need to add `null=True` in our model:

```python
pub_time = models.TimeField(blank=True, null=True)
```

Be aware though that if you change the `null` value of a model field, you will have to create a new migration and apply it, so the database schema is updated to set the `NULL` or `NOT NULL`. 

An exception to the above is if you are using `CharField` or `TextField`. For both of these fields, Django saves an empty string if `blank=True`. For example, if we want to make the title field optional we can do it like so:

```python
title = models.CharField(max_length=200, blank=True)
pub_date = models.DateField()
pub_time = models.TimeField(blank=True, null=True)
```

Although we could still set a `null=True` on the title field, the Django convention is to avoid using `null=True` for `CharField` and `TextField` since these fields could have two different values for "no data": `None` or an empty string `""`.

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*Source: [sentry.io/answers/django-difference-between-null-and-blank/](https://sentry.io/answers/django-difference-between-null-and-blank/)*