Relations

Relations#

Get relations#

from plone import api

friendship = api.relation.get(
    source=source, target=target, relationship="friend", unrestricted=False, as_dict=False
    )

You must provide either source, target, or relationship, or a combination of those, to api.relation.get(). unrestricted and as_dict are optional.

By default the result is a list of z3c.relationfield.RelationValue objects. If you set as_dict=True api.relation.get() will return a dictionary with the names of the relations as keys and lists of objects as values.

By default the View permission is checked on the relation objects. You only get objects that you are allowed to see. Use the unrestricted parameter if you want to bypass this check.

To get back relations, so relations pointing to an item, use:

friendships = api.relation.get(target=target)

To get the objects connected by relations you can use the api of these return values:

for relation in api.relation.get(source=source):
    source = relation.from_object
    target = relation.to_object
    relationship = relation.from_attribute

Create relation#

To create a relation between source object and target object, use api.relation.create().

from plone import api

portal = api.portal.get()
source = portal.bob
target = portal.bobby
api.relation.create(source=source, target=target, relationship="friend")

If the relation is based on a RelationChoice or RelationList field on the source object, the value of that field is created/updated accordingly.

Delete relation#

Delete one or more relations:

api.relation.delete(source=source, target=target, relationship="friend")

In order to delete relation(s), you must provide either source, target, or relationship to api.relation.delete(). You can mix and match.

Delete all relations from source to any target:

api.relation.delete(source=source)

Delete all relations from any source to this target:

api.relation.delete(target=target)

Delete relations with name "friend" from source to any target:

api.relation.delete(source=source, relationship="friend")

Delete relations with name "uncle" from any source to this target:

api.relation.delete(target=target, relationship="uncle")

Delete relations with name "enemy" from any source to any target:

api.relation.delete(relationship="enemy")

If a deleted relation is based on a RelationChoice or RelationList field on the source object, the value of the field is removed/updated accordingly.

Further reading#

For more information on possible flags and usage options please see the full plone.api.relation specification. For more information on relations read the relevant chapter in the Mastering Plone training.

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