Docs Menu
Docs Home
/
Languages
/
Python
/
Django MongoDB Backend
/
Interact with Data

Perform CRUD Operations

On this page

  • Overview
  • Query API
  • Sample Data
  • Insert Documents
  • Example
  • Read Documents
  • Return Multiple Documents Example
  • Return One Document Example
  • Modify Documents
  • Example
  • Delete Documents
  • Example
  • Additional Information

Overview

In this guide, you can learn how to use Django MongoDB Backend to run create, read, update, and delete (CRUD) operations on your MongoDB collection.

You can also use the Django admin site to edit your models and their corresponding collections on a web interface. For more information, see the Django Admin Site entry in the Django documentation.

Query API

You can use methods provided by the Django QuerySet API to run CRUD operations. To run these operations, you can call QuerySet methods on your model's manager. The Manager class handles database operations and allows you to interact with your MongoDB data by referencing Django models. By default, Django adds a Manager named objects to every model class.

Tip

To learn more about Django's QuerySet API, see QuerySet in the Django documentation.

This guide shows how to use the following QuerySet methods:

  • create(): Inserts documents into the collection

  • filter() and get(): Retrieves one or multiple collection documents

  • update(): Modifies collection documents

  • delete(): Deletes collection documents

Sample Data

The examples in this guide use the Movie model, which represents the sample_mflix.movies collection from the Atlas sample datasets. The Movie model class has the following definition:

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), null=True, blank=True)
    class Meta:
        db_table = "movies"
        managed = False
    
    def __str__(self):
        return self.title

The Movie model includes an inner Meta class, which specifies model metadata, and a __str__() method, which defines the model's string representation. To learn about these model features, see Define a Model in the Create Models guide.

Run Code Examples

You can use the Python interactive shell to run the code examples. To enter the shell, run the following command from your project's root directory:

python manage.py shell

After entering the Python shell, ensure that you import the following models and modules:

from <your application name>.models import Movie
from django.utils import timezone
from datetime import datetime

To learn how to create a Django application that uses the Movie model and the Python interactive shell to interact with MongoDB documents, visit the Get Started with Django MongoDB Backend tutorial.

Insert Documents

To insert a document into a collection, call the create() method on your model's manager. Pass the new document's field names and field values as arguments to the create() method.

Example

The following example calls the create() method to insert a document into the sample_mflix.movies collection. The new document has a title value of "Poor Things" and a runtime value of 141:

Movie.objects.create(title="Poor Things", runtime=141)

The create() method allows you to create a new Movie object and save the object to MongoDB in one method call. Alternatively, you can create a Movie object and call save(), as shown in the following code:

movie = Movie(title="Poor Things", runtime=141)
movie.save()

Tip

To learn more about the create() method, see create in the Django documentation.

Read Documents

To retrieve documents from your collection, call the filter() method on your model's manager. Pass a query filter, or criteria that specifies which documents to retrieve, as an argument to the filter() method.

Alternatively, you can call the get() method to retrieve a single document that matches your query.

Return Multiple Documents Example

The following example calls the filter() method to retrieve documents from the sample_mflix.movies collection. The query returns Movie objects that represent movies released on January 1, 2000:

Movie.objects.filter(released=timezone.make_aware(datetime(2000, 1, 1)))
 <QuerySet [<Movie: The Bumblebee Flies Anyway>, <Movie: Angels of the Universe>,
 <Movie: First Person Plural>, <Movie: Just, Melvin: Just Evil>, <Movie: Sound and Fury>,
 <Movie: Peppermint Candy>]>

Tip

To learn more about the filter() method, see filter in the Django documentation.

Return One Document Example

To retrieve only one document that matches your query criteria, call the get() method and pass a query filter as an argument. The following example retrieves a document in which the title value is "Boyhood":

Movie.objects.get(title="Boyhood")
 <Movie: Boyhood>

Important

If your query matches no documents or multiple documents, the get() method generates an error. To retrieve one document from a query that might match multiple, chain the first() method to filter(), as shown in the following code:

Movie.objects.filter(title="Boyhood").first()

Tip

To learn more about the get() method, see get in the Django documentation.

Modify Documents

To modify documents in a collection, call the filter() and update() methods on your model's manager. Pass a query filter, or criteria that specifies which documents to update, as an argument to the filter() method. Then, pass the fields and values you want to update as arguments to the update() method.

Example

The following example calls the update() method to modify documents in the sample_mflix.movies collection. The code matches a document that has a title value of "High Fidelity" and adds a plot field:

Movie.objects.filter(
    title="High Fidelity").update(
    plot="Rob, a record store owner, recounts his top five breakups,including the one in progress.")
 // Outputs the number of modified documents
 1

Tip

To learn more about the update() method, see update in the Django documentation.

Delete Documents

To delete documents in a collection, call the filter() and delete() methods on your model's manager, Pass a query filter, or criteria that specifies which documents to delete, as an argument to the filter() method.

Example

The following example calls the delete() method to delete documents in the sample_mflix.movies collection. The code matches and deletes documents that have a runtime value of 5:

Movie.objects.filter(runtime=5).delete()
 // Outputs the number of deleted documents and objects
 (16, {'sample_mflix.Movie': 16})

Tip

To learn more about the delete() method, see delete in the Django documentation.

Additional Information

To learn more about performing read operations, see the Specify a Query guide.

To view more create, read, update, and delete examples, see the following steps of the Get Started with Django MongoDB Backend tutorial:

Back

Interact with Data

Next

Specify a Query