Local Development

Setup

For a local installation start with:

  1. pip install djongo
  2. Into settings.py file of your project, add:

       DATABASES = {
           'default': {
               'ENGINE': 'djongo',
               'NAME': 'your-db-name',
           }
       }
    

Requirements

  1. Python 3.6 or higher.
  2. MongoDB 3.4 or higher.
  3. If your models use nested queries or sub querysets like:

       inner_query = Blog.objects.filter(name__contains='Ch').values('name')
       entries = Entry.objects.filter(blog__name__in=inner_query)
    

    MongoDB 3.6 or higher is required.

MongoDB and Django

EmbeddedField

Nest a dict inside a model with the EmbeddedField. The model_container is used to describe the structure of the data stored.

from djongo import models

class Blog(models.Model):
    name = models.CharField(max_length=100)

    class Meta:
        abstract = True

class Entry(models.Model):
    blog = models.EmbeddedField(
        model_container=Blog
    )    
    headline = models.CharField(max_length=255)    

e = Entry()
e.blog = {
    'name': 'Djongo'
}
e.headline = 'The Django MongoDB connector'
e.save()

ArrayField

Nest a list of dict inside a model for more complex data.

from djongo import models

class Entry(models.Model):
    blog = models.ArrayField(
        model_container=Blog
    )    
    headline = models.CharField(max_length=255)    

e = Entry()
e.blog = [
    {'name': 'Djongo'}, {'name': 'Django'}, {'name': 'MongoDB'}
]
e.headline = 'Djongo is the best Django and MongoDB connector'
e.save()

Database Configuration

The settings.py supports (but is not limited to) the following options:

Attribute Value Description
ENGINE djongo The MongoDB connection engine for interfacing with Django.
ENFORCE_SCHEMA True Ensures that the model schema and database schema are exactly the same. Raises Migration Error in case of discrepancy.
ENFORCE_SCHEMA False (Default) Implicitly creates collections. Returns missing fields as None instead of raising an exception.
NAME your-db-name Specify your database name. This field cannot be left empty.
LOGGING dict A dictConfig for the type of logging to run on djongo.
CLIENT dict A set of key-value pairs that will be passed directly to MongoClient as kwargs while creating a new client connection.

All options except ENGINE and ENFORCE_SCHEMA are the same those listed in the pymongo documentation.

    DATABASES = {
        'default': {
            'ENGINE': 'djongo',
            'NAME': 'your-db-name',
            'ENFORCE_SCHEMA': False,
            'CLIENT': {
                'host': 'host-name or ip address',
                'port': port_number,
                'username': 'db-username',
                'password': 'password',
                'authSource': 'db-name',
                'authMechanism': 'SCRAM-SHA-1'
            },
            'LOGGING': {
                'version': 1,
                'loggers': {
                    'djongo': {
                        'level': 'DEBUG',
                        'propagate': False,                        
                    }
                },
             },
        }
    }

DjongoCS

Djongo Cloud Server is the fastest way to deploy to the cloud your djongo powered apps. The DjongoCS package and dependencies come preconfigured and installed on the Cloud.

SSH

On account creation you install your public SSH key at the dashboard. This gives a secure shell access to the VM instance for uploading a Django App. Once the key is installed, the dashboard displays the SSH port number over which you can connect to the VM instance.

Establish a secure shell connection using:

ssh <user>@api.djongomapper.com -p <port> 

The user is the same as the username used while creating the account.

Public API

When you create an account on DjongoCS you get a unique URL path assigned to you. The Django views that you create for servicing your API can be accessed and extended further starting from the base URL:

https://api.djongomapper.com/<user> 

Launching the App

Establishing a SSH connection to your server logs you into the /home/$USER directory. The typical home directory structure looks like:

~home
| -- .ssh/
| -- site/
|   -- api/
|     -- settings.py
|     -- urls.py
|   -- app/
|     -- app1/
|       -- views.py
|       -- models.py
|     -- app2/
|       -- views.py
|       -- models.py

In your urls.py if you add an entry like path('hello/', app1.views.hello), the URL path becomes https://api.djongomapper.com/<user>/hello

Reload the Server

After making changes to your app, you need to reload the server. This is done by clicking the reload button in your dashboard.

Security and Integrity Checks

Djongo allows for checks on data fields before they are saved to the database. Running the correct integrity checks and field value validators before writing data into the database is important.

Enforce schema

MongoDB is schemaless, which means no schema rules are enforced by the database. You can add and exclude fields per entry and MongoDB will not complain. This can make life easier, especially when there are frequent changes to the data model. Take for example the Blog Model (version 1).

class Blog(models.Model):
    name = models.CharField(max_length=100)
    tagline = models.TextField()

You can save several entries into the DB and later modify it to version 2:

class Blog(models.Model):
    name = models.CharField(max_length=100)
    tagline = models.TextField()
    description = models.TextField()

The modified Model can be saved without running any migrations.

This works fine if you know what you are doing. Consider a query that retrieves entries belonging to both the ‘older’ model (with just 2 fields) and the current model. What will the value of description now be? To handle such scenarios Djongo comes with the ENFORCE_SCHEMA option.

When connecting to Djongo you can set ENFORCE_SCHEMA: True. In this case, a MigrationError will be raised when field values are missing from the retrieved documents. You can then check what went wrong.

ENFORCE_SCHEMA: False works by silently setting the missing fields with the value None. If your app is programmed to expect this (which means it is not a bug) you can get away by not calling any migrations.

Validators

Apply validators to each field before they are saved.

from django.core.exceptions import ValidationError
from django.utils.translation import gettext_lazy as _
from djongo import models
from django.core.validators import URLValidator

def script_injection(value):
    if value.find('<script>') != -1:
        raise ValidationError(_('Script injection in %(value)s'),
                              params={'value': value})

class Address(models.Model)
    city = models.CharField(max_length=50)
    homepage = models.URLField(validators=[URLValidator, script_injection])
    class Meta:
        abstract=True

class Entry(models.Model):
    _id = models.ObjectIdField()
    address = models.EmbeddedField(model_container=Address)

Integrity checks

class Entry(models.Model):
    _id = models.ObjectIdField()
    address = models.EmbeddedField(model_container=Address,
                                   null=False,
                                   blank=False)

By setting null=False, blank=False in EmbeddedField, missing values are never stored.

Djongo Manager

Djongo Manager extends the functionality of the usual Django Manager. It gives direct access to the pymongo collection API. To use this manager define your manager as DjongoManager in the model.

class Entry(models.Model):
    blog = models.EmbeddedField(
        model_container=Blog,
    )
    headline = models.CharField(max_length=255)    
    objects = models.DjongoManager()

Use it like the usual Django manager:

post = Entry.objects.get(pk=p_key)

Will get a model object having primary key p_key.

Using PyMongo Commands

MongoDB has powerful query syntax and DjongoManager lets you exploit it fully. For the above Entry model define a custom query function:

class EntryView(DetailView):

    def get_object(self, queryset=None):
        index = [i for i in Entry.objects.mongo_aggregate([
            {
                '$match': {
                    'headline': self.kwargs['path']
                }
            },
        ])]

        return index

You can directly access any pymongo command by prefixing mongo_ to the command name.

For example, to perform aggregate on the BlogPage collection (BlogPage is stored as a table in SQL or a collection in MongoDB) the function name becomes mongo_aggregate. To directly insert a document (instead of .save() a model) use mongo_insert_one()

GridFS

To save files using GridFS you must create a file storage instance of GridFSStorage:

grid_fs_storage = GridFSStorage(collection='myfiles')

In your model define your field as FileField or ImageField as usual:

avatar = models.ImageField(storage=grid_fs_storage, upload_to='')

Refer to Using GridFSStorage for more details.

DjongoCS Features

Features under development on DjongoCS are not a part of the standard Djongo package. Visit the support page for more information.

DjongoCS supports multiple features of MongoDB including:

Indexes

Support for indexes provided by MongoDB, for example 2dSphere Index, Text Index and Compound Indexes.

Model Query

Support for GeoSpatial Queries and Tailable Cursors.

Model Update

Unordered and Ordered Bulk Writes.

Database Transactions

Atomic multi document transactions with commit and rollback support.

Schema Validation and Model Creation

Automatic JSON Schema validation document generation and options to add Read and Write Concerns for the Models.

Aggregation Operators

Support for various aggregation operators provided by MongoDB.

Contribute

If you think djongo is useful, please share it with the world! Your endorsements and online reviews will help get more support for this project.

You can contribute to the source code or the documentation by creating a simple pull request! You may want to refer to the design documentation to get an idea on how Django MongoDB connector is implemented.