Django Field Types

BooleanField

If you need to accept null values then use NullBooleanField instead.

Note

NullBooleanField is deprecated in version 3.1

CharField

To create a CharField which can be blank, specify only blank.

If your CharField includes choices, then you can get the human-readable name using get_FOO_display():

COLOUR_CHOICES = [
    (GREEN, "Green"),
    (RED, "Red"),
]
colour = models.CharField(max_length=30, blank=True, choices=COLOUR_CHOICES)

# In the template
{{ object.get_colour_display }}

DateTimeField

To create a DateTimeField which can be blank, specify blank AND null.

Update

To update a created field with auto_now_add (e.g. models.DateTimeField(auto_now_add=True):

sales_order.save()
# The 'created' field is 'auto_now' in the 'sales_order' model
# https://stackoverflow.com/questions/7499767/temporarily-disable-auto-now-auto-now-add
sales_order.created = created_at
sales_order.save(update_fields=["created"])

DecimalField

For now (because I can’t find it in the docs), I am creating a DecimalField which can be blank with blank AND null (the same as an IntegerField).

rate = models.DecimalField(max_digits=8, decimal_places=2)

EmailField

The EmailField is a CharField so for blank, we will specify only blank.

FileField and ImageField

To create a FileField or ImageField which can be blank:

I am not sure what to do here, but we will try copying a CharField, so specify only blank.

File System

From Loading Django FileField and ImageFields from the file system:

from django.db import models

class Company(models.Model):
    name = models.CharField(max_length=100)
    logo = models.ImageField()


import requests
from django.core.files import File
from pathlib import Path

from .models import Company

r = requests.get("http://media.revsys.com/img/revsys-logo.png")

with open("/tmp/revsys-logo.png", "wb") as f:
    f.write(r.content)

reopen = open("/tmp/revsys-logo.png", "rb")
django_file = File(reopen)

revsys = Company()
revsys.name = "Revolution Systems"
revsys.logo.save("revsys-logo.png", django_file, save=True)

Read

To read from a FileField:

data = schedule.output.readlines()

S3 / Spaces

To get the private URL for a field use the url method:

>>> x = Invoice.objects.last()
>>> x.pdf
<FieldFile: invoice/2025/11/04/001913.pdf>
>>> x.pdf.url
'https://lon1.digitaloceanspaces.com/kbsoftware/private/invoice/2025/11/04/001913.pdf?...

ForeignKey

To create an optional ForeignKey, specify blank AND null e.g: mentor = models.ForeignKey(MentorModel, blank=True, null=True)

Filter:

qs = Ticket.objects.filter(ticket_type__isnull=True)

IntegerField

To create an IntegerField which can be blank, specify blank AND null.

JSONField

from django.core.serializers.json import DjangoJSONEncoder
parameters = JSONField(blank=True, null=True, encoder=DjangoJSONEncoder)

Date and Time

To dump json data using the DjangoJSONEncoder:

import json
from django.core.serializers.json import DjangoJSONEncoder
print(json.dumps(result, indent=4, cls=DjangoJSONEncoder))

If you add a date / time to the JSONField e.g:

my_model.parameters = {
    "contact_pk": contact.pk,
    "from_date": from_date,
    "to_date": to_date,
}

You need to parse them e.g:

from dateutil.parser import parse
from_date = parse(parameters.get("from_date"))

ManyToManyField

app_group = models.ManyToManyField(AppGroup, blank=True)

Note

I tried setting null=True, but I got the following warning from migrations:: (fields.W340) null has no effect on ManyToManyField.

TextField

To create a TextField which can be blank, specify only blank.

URLField

The URLField is a CharField so for blank, we will specify only blank.

UUIDField

I am adding a uuid field (I couldn’t find a way to convert an existing id field):

uuid = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)

To allow null:

uuid = models.UUIDField(null=True)

For more details, see the Django UUIDField documentation and Will Django UUIDFIeld behave correctly?