Create Models

Django Fields

The following table describes the Django model fields that Django MongoDB Backend supports:

MongoDB BSON Fields

MongoDB organizes and stores documents in a binary representation called BSON that allows for flexible data processing.

The following table describes supported BSON field types and their Django MongoDB Backend equivalents that you can use in your Django models:

Example

This sample models.py file defines a Movie model class that includes the following information:

• List of fields that represent movie data.

• Meta class that sets the db_table option to movies. This instructs Django MongoDB Backend to use this model to represent the sample_mflix.movies collection from the Atlas sample datasets.

  The Meta class also sets the managed option to False, instructing Django MongoDB Backend not to create a new collection for the model.

• __str__() method that defines the model's string representation as its title field value.

from django.db import models
class Movie(models.Model):
    title = models.CharField(max_length=200)
    plot = models.TextField(blank=True)
    runtime = models.IntegerField(default=0)
    released = models.DateTimeField("release date", null=True, blank=True)
    class Meta:
        db_table = "movies"
        managed = False
    
    def __str__(self):
        return self.title

Use a JSONField

You can use a JSONField in your model to store JSON objects. JSON is a human-readable format for data exchange, and JSON objects are data containers that map string keys to values. MongoDB provides the Object field type to store JSON data in documents and internally stores this data in BSON, or Binary JSON, format.

from django.db import models
class Movie(models.Model):
    title = models.CharField(max_length=200)
    plot = models.TextField(blank=True)
    runtime = models.IntegerField(default=0)
    released = models.DateTimeField("release date", null=True, blank=True)
    imdb = models.JSONField(null=True, blank=True)
    class Meta:
        db_table = "movies"
        managed = False
    
    def __str__(self):
        return self.title

Use an ArrayField

You can use an ArrayField in your model to store a list of data. To create an ArrayField, use the ArrayField() class constructor and pass the following arguments:

• base_field: Specifies the underlying data type of each value stored in the array. You cannot specify EmbeddedModelField or FileField as the base field type.

• size: (Optional) Specifies the maximum size of the array.

• options: (Optional) Specifies Django field options. To view a list of available options, see Field options in the Django documentation.

from django.db import models
from django_mongodb_backend.fields import ArrayField
class Movie(models.Model):
    title = models.CharField(max_length=200)
    plot = models.TextField(blank=True)
    runtime = models.IntegerField(default=0)
    released = models.DateTimeField("release date", null=True, blank=True)
    genres = ArrayField(
             models.CharField(max_length=100),
             size=5,
             null=True,
             blank=True)
    class Meta:
        db_table = "movies"
        managed = False
    
    def __str__(self):
        return self.title

Use an EmbeddedModelField

You can use an EmbeddedModelField to represent a MongoDB Object, which stores a nested document value. This type allows one model to store a separate model in one of its fields. To create an EmbeddedModelField, define an embedded model class as a subclass of the EmbeddedModel abstract model. Then, create a field in your base model class by using the EmbeddedModelField() constructor and pass the following arguments:

• embedded_model: Specifies the model class to store.

• options: (Optional) Specifies Django field options. To view a list of available options, see Field options in the Django documentation.

from django.db import models
from django_mongodb_backend.models import EmbeddedModel
from django_mongodb_backend.fields import EmbeddedModelField
class Award(EmbeddedModel):
    wins = models.IntegerField(default=0)
    nominations = models.IntegerField(default=0)
    text = models.CharField(max_length=100)
class Movie(models.Model):
    title = models.CharField(max_length=200)
    plot = models.TextField(blank=True)
    runtime = models.IntegerField(default=0)
    released = models.DateTimeField("release date", null=True, blank=True)
    awards = EmbeddedModelField(Award, null=True, blank=True)
    class Meta:
        db_table = "movies"
        managed = False
    
    def __str__(self):
        return self.title