Document

Documents

Documents are the basic building blocks of MongoKit. They define the schema of each document and how that document should be accessed

Document Class

from mongokit import Document, Connection

class MyDocument(Document):
    structure = {
        ...
    }
    required_fields = [
        ...
    ]
    default_values = {
        ...
    }

You can read more about the structure attribute, and the required_fields and default_values descriptors. They are the primary definition of a document. MongoKit also supports handling i18n, indexes, and migration.

Registering

Once a document has been defined, it must be registered with a Connection:

connection = Connection()
connection.register([MyDocument])

Optionally, the register method can be used as a decorator:

    @connection.register
    class MyDocument(Document):
        structure = {...}

Database and Collection

To use a Document, you must call it from a collection. In pymongo's syntax, you would use connection.<database>.<collection> to access the collection. Once you have the collection, you can create a new document:

>>> connection.database.collection.MyDocument()
{... new Document's default values ...}

As a short cut, you can define the database and colleciton names in the Document definition:

@connection.register
class MyDocument(Document):
    __collection__ = 'collection_name'
    __database__ = 'database_name'
    structure = {...}

Now, we can have access to our document directly from the connection:

>>> connection.MyDocument()
{... new Document's default values ...}

Note that if you want to specify the __database__, you should also specify the __collection__ attribute.

It is also possible to access the Document from the database:

>>> connection.database.MyDocument() # this will use __collection__ as collection name

This matches the typical pattern of creating and passing around a db object:

>>> connection = Connection()
>>> db = connection[MONGODB_DATABASE_NAME]
>>> db.MyDocument()

Changing Collection Dynamically

You might need to specify a different db or collection dynamically. For instance, say you want to store a User by database.

>>> class User(Document):
...     structure = {'login':unicode, 'screen_name':unicode}

>>> con.register([User])

Like pymongo, MongoKit allow you to change those parameters on the fly:

>>> user_name = 'namlook'
>>> user_collection = connection[user_name].profile #returns a reference to the database 'namlook' in the collection 'profile'.

Now, we can query the database by passing our new collection:

>>> profiles = user_col.User.find()

>>> user = user_col.User()
>>> user['login'] = '[email protected]'
>>> user['screen_name'] = 'Namlook'

Calling user.save() will save the object into the database namlook in the collection profile.

Dot Notation

If you want to use the dot notation (ala javascript), you must set the use_dot_notation attribute to True:

class TestDotNotation(Document):
    use_dot_notation = True

    structure = {
        'foo':{
            'bar': basestring
        }
    }

then

>>> connection.register([TestDotNotation])
>>> doc = connection.database.TestDotNotation()
>>> doc.foo.bar = 'blah'
>>> doc
{'foo': {'bar': 'blah'}}

Note that if an attribute is not in structure, the value will be added as attribute:

>>> doc.arf = 3 # arf is not in structure
>>> doc
{'foo': {'bar': u'bla'}}

If you want to be warned when a value is set as attribute, you can set the dot_notation_warning attribute as True.

Polymorphism

In the following example, we have two objects, A and B, which inherit from Root. And we want to build an object C from A and B. Let's build Root, A and B first:

from mongokit import *
class Root(Document):
    structure = {
        'root': int
    }
    required_fields = ['root']

class A(Root):
    structure = {
        'a_field': basestring,
    }
    required_fields = ['a_field']


class B(Root):
    structure = {
        'b_field': basestring,
    }

Polymorphisms just work as expected:

class C(A,B):
    structure = {'c_field': float}

then

>>> c = C()
>>> c == {'b_field': None, 'root': None, 'c_field': None, 'a_field': None}
True
>>> C.required_fields
['root', 'a_field']