Update

Updating data

Update in Mongokit is as easy than saving an object. Just modify your document and save it:

    @connection.register
    ... class MyDoc(Document):
    ...    structure = {
    ...        'foo':{
    ...            'bar':[unicode],
    ...            'eggs':{'spam':int},
    ...        },
    ...        'bla':unicode
    ...    }

    >>> doc = self.col.MyDoc()
    >>> doc['_id'] = 3
    >>> doc['foo']['bar'] = [u'mybar', u'yourbar']
    >>> doc['foo']['eggs']['spam'] = 4
    >>> doc['bla'] = u'ble'
    >>> doc.save() 

Let's modify our doc:

    >>> doc['foo']['eggs']['spam'] = 2
    >>> doc['bla']= u'bli'
    >>> doc.save()

IMPORTANT: You have to be conscient that updating a document like that is not atomic. To do so, please read the next section.

Bulk and atomic updates

As Mongokit expose all the pymongo API, you can use the pymongo's update on collection:

>>> con.test.tutorial.update({'title': 'my first blog post'}, {'$set':{'title':u'my very first blog post'}})

For more information, please look at the pymongo documentation.

reload()

If a document was updated in another thread, it would be interesting to refresh the document to match changes from the database. To do that, use the reload() method.

Two thing you should know before using this method:

• If no _id is set in the document, a KeyError is raised.
• If a document is not saved into the database, the OperationFailure exception is raised.
• using reload() will erase all unsaved values !

Example:

    >>> @connection.register
    ... class MyDoc(Document):
    ...    __database__ = 'test'
    ...    __collection__ = 'tutorial'
    ...    structure = {
    ...        'foo':{
    ...            'eggs':{'spam':int},
    ...        },
    ...        'bla':unicode
    ...    }

    >>> doc = connection.MyDoc()
    # calling reload() here will raise a KeyError
    >>> doc['_id'] = 3
    >>> doc['foo']['eggs']['spam'] = 4
    >>> doc['bla'] = u'ble'
    # calling reload() here will raise an OperationFailure
    >>> doc.save()
    >>> doc['bla'] = u'bli' # we don't save this change this will be erased
    >>> connection.test.tutorial.update({'_id':doc['_id']}, {'$set':{'foo.eggs.spam':2}})
    >>> doc.reload()
    >>> doc
    {'_id': 3, 'foo': {u'eggs': {u'spam': 2}}, 'bla': u'ble'}

find_and_modify()

This method allow to return a Document object after or before making an update.

If you call find_and_modify on a Collection object, it will return a dict object:

    >>> d = connection.test.tutorial.find_and_modify({'bla':'ble'}, {'$set':{'foo.eggs.spam':2}})
    >>> isinstance(d, MyDoc)
    False
    >>> isinstance(d, dict)
    True

If you call find_and_modify on a Document object, it will return a Document object:

    >>> d = connection.MyDoc.find_and_modify({'bla':'ble'}, {'$set':{'foo.eggs.spam':2}})
    >>> isinstance(d, MyDoc)
    True

Please, read the mongodb documentation to learn how to use the find_and_modify method.