son_manipulator
– Manipulators that can edit SON documents as they are saved or retrieved¶
Manipulators that can edit SON objects as they enter and exit a database.
New manipulators should be defined as subclasses of SONManipulator and can be installed on a database by calling pymongo.database.Database.add_son_manipulator.
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class
pymongo.son_manipulator.
AutoReference
(db)¶ Transparently reference and de-reference already saved embedded objects.
This manipulator should probably only be used when the NamespaceInjector is also being used, otherwise it doesn’t make too much sense - documents can only be auto-referenced if they have an _ns field.
NOTE: this will behave poorly if you have a circular reference.
TODO: this only works for documents that are in the same database. To fix this we’ll need to add a DatabaseInjector that adds _db and then make use of the optional database support for DBRefs.
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transform_incoming
(son, collection)¶ Replace embedded documents with DBRefs.
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transform_outgoing
(son, collection)¶ Replace DBRefs with embedded documents.
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will_copy
()¶ We need to copy so the user’s document doesn’t get transformed refs.
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class
pymongo.son_manipulator.
NamespaceInjector
¶ A son manipulator that adds the _ns field.
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transform_incoming
(son, collection)¶ Add the _ns field to the incoming object
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class
pymongo.son_manipulator.
ObjectIdInjector
¶ A son manipulator that adds the _id field if it is missing.
Changed in version 2.7: ObjectIdInjector is no longer used by PyMongo, but remains in this module for backwards compatibility.
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transform_incoming
(son, collection)¶ Add an _id field if it is missing.
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class
pymongo.son_manipulator.
ObjectIdShuffler
¶ A son manipulator that moves _id to the first position.
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transform_incoming
(son, collection)¶ Move _id to the front if it’s there.
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will_copy
()¶ We need to copy to be sure that we are dealing with SON, not a dict.
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class
pymongo.son_manipulator.
SONManipulator
¶ A base son manipulator.
This manipulator just saves and restores objects without changing them.
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transform_incoming
(son, collection)¶ Manipulate an incoming SON object.
Parameters: - son: the SON object to be inserted into the database
- collection: the collection the object is being inserted into
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transform_outgoing
(son, collection)¶ Manipulate an outgoing SON object.
Parameters: - son: the SON object being retrieved from the database
- collection: the collection this object was stored in
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will_copy
()¶ Will this SON manipulator make a copy of the incoming document?
Derived classes that do need to make a copy should override this method, returning True instead of False. All non-copying manipulators will be applied first (so that the user’s document will be updated appropriately), followed by copying manipulators.
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