sqlalchemy.orm.attributes

Delete the value of an attribute, firing history events.

This function may be used regardless of instrumentation applied directly to the class, i.e. no descriptors are required. Custom attribute management schemes will need to make usage of this method to establish attribute state as understood by SQLAlchemy.

Mark an instance as 'dirty' without any specific attribute mentioned.

This is a special operation that will allow the object to travel through the flush process for interception by events such as .SessionEvents.before_flush. Note that no SQL will be emitted in the flush process for an object that has no changes, even if marked dirty via this method. However, a .SessionEvents.before_flush handler will be able to see the object in the .Session.dirty collection and may establish changes on it, which will then be included in the SQL emitted.

Mark an attribute on an instance as 'modified'.

This sets the 'modified' flag on the instance and establishes an unconditional change event for the given attribute. The attribute must have a value present, else an .InvalidRequestError is raised.

To mark an object "dirty" without referring to any specific attribute so that it is considered within a flush, use the .attributes.flag_dirty call.

Get the value of an attribute, firing any callables required.

This function may be used regardless of instrumentation applied directly to the class, i.e. no descriptors are required. Custom attribute management schemes will need to make usage of this method to make usage of attribute state as understood by SQLAlchemy.

Return a .History record for the given object and attribute key.

This is the pre-flush history for a given attribute, which is reset each time the .Session flushes changes to the current database transaction.

Initialize a collection attribute and return the collection adapter.

This function is used to provide direct access to collection internals for a previously unloaded attribute. e.g.:

collection_adapter = init_collection(someobject, 'elements')
for elem in values:
    collection_adapter.append_without_event(elem)

For an easier way to do the above, see ~sqlalchemy.orm.attributes.set_committed_value.

Set the value of an attribute, firing history events.

This function may be used regardless of instrumentation applied directly to the class, i.e. no descriptors are required. Custom attribute management schemes will need to make usage of this method to establish attribute state as understood by SQLAlchemy.

Set the value of an attribute with no history events.

Cancels any previous history present. The value should be a scalar value for scalar-holding attributes, or an iterable for any collection-holding attribute.

This is the same underlying method used when a lazy loader fires off and loads additional data from the database. In particular, this method can be used by application code which has loaded additional attributes or collections through separate queries, which can then be attached to an instance as though it were part of its original loaded state.