Model Options

In addition to Django’s default Meta options, Django MongoDB Engine supports various options specific to MongoDB through a special class MongoMeta.

class FooModel(models.Model):
    class MongoMeta:
        # Mongo options here


Django MongoDB Engine already understands the standard db_index and unique_together options and generates the corresponding MongoDB indexes on syncdb.

To make use of other index features, like multi-key indexes and Geospatial Indexing, additional indexes can be specified using the indexes setting.

class Club(models.Model):
   location = ListField()
   rating = models.FloatField()
   admission = models.IntegerField()
   class MongoMeta:
      indexes = [
         [('rating', -1)],
         [('rating', -1), ('admission', 1)],
         {'fields': [('location', '2d')], 'min': -42, 'max': 42},

indexes can be specified in two ways:

  • The simple “without options” form is a list of (field, direction) pairs. For example, a single ascending index (the same thing you get using db_index) is expressed as [(field, 1)]. A multi-key, descending index can be written as [(field1, -1), (field2, -1), ...].
  • The second form is slightly more verbose but takes additional MongoDB index options. A descending, sparse index for instance may be expressed as {'fields': [(field, -1)], 'sparse': True}.

Capped Collections

Use the capped option and collection_size (and/or collection_max) to limit a collection in size (and/or document count), new documents replacing old ones after reaching one of the limit sets.

For example, a logging collection fixed to 50MiB could be defined as follows:

class LogEntry(models.Model):
    timestamp = models.DateTimeField()
    message = models.TextField()
    class MongoMeta:
        capped = True
        collection_size = 50*1024*1024