BinaryField — Django Models

Michael Zippo

Syntax

 field_name = models.BinaryField ( ** options )

Django BinaryField Model Explanation

BinaryField illustration using example. Consider a project named pythonengineering that has an application named geeks .

Refer to the following articles to check how to create a project and an app in Django.

How to Create a Basic Project using MVT in Django?

How to Create an App in Django?

Enter the following code into the models.py file of the geeks application.

Add the geek app to INSTALLED_APPS

from django.db import models

from django.db.models import Model

# Create your models here.

class GeeksModel (Model):

geeks_field = models.BinaryField ()

Now when we run the makemigrations command from the terminal,

 Python manage.py makemigrations

In the geeks directory a new folder named migrations will be created with a file named 0001_initial.py

# Application definition

INSTALLED_APPS = [

’ django .contrib.admin’ ,

’django.contrib.auth’ ,

’django.contrib.contenttypes’ ,

’ django.contrib.sessions’ ,

’django.contrib.messages’ ,

’django.contrib.staticfiles’ ,

’geeks’ ,

]

# Generated by Django 2.2.5 on 2019-09- 06:00 25

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.BinaryField ()),

] ,

),

]

So the geeks_field BigIntegerField is created when you run makemigrations for the project. This is a field for storing raw binary data.

How to use BinaryField?

Any data type can be converted to bytes, including integers, strings, images, etc. Let’s try to save a string in the BinaryField. The string can be converted to bytes using the generic byte function. This function internally points to the CPython library, which implicitly calls the encoding function to convert the string to the specified encoding.

# model import
# from a geek app

from geeks.models import GeeksModel

# create string

test_string = "GFG is best"

# create byte object

res = bytes (test_string, ’utf-8’ )

# instantiate
# GeeksModel

geek_object = GeeksModel.objects.create (geeks_field = res)

geek_object.save ()

Now let’s check it out on the admin server. We have created a GeeksModel instance

Possible Errors

How stated, BinaryField is a non-editable field, if you manually try to make it editable with editable = True it will result in unexpected errors. It must be created in a function so that objects can be allocated to it.

Field options

Field options — they are arguments given to each field to apply some constraint or to convey a particular characteristic to a particular field. For example, adding the null = True argument to the BinaryField will allow it to store empty values for that table in a relational database.
Here are the options and attributes that the BinaryField 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.
Choices	An iterable (eg, a list or tuple) of 2-tuples to use as choices for this field.
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 .
Unique	If True, this field must be unique throughout the table.