Unique identifiers (UIDs)

UID is a unique, non-human-readable identifier for a content object which stays on the object even if the object is moved.

Plone uses UIDs for

• Storing content-to-content references (Archetypes, ReferenceField)
• Linking by UIDs (Kupu) - this enables persistent links even though the object is moved

Warning

Dexterity content framework does not use UIDS, but integer ids (intids) to manage references.

• More information about Dexterity reference system

Getting the object’s UID

Use UID() accessor function:

>>> site.events.UID()
'ce380ef0f10a85beb864025928e1819b'

Looking up object by UID

Use lookupObject() in reference catalog.

>>> site.reference_catalog.lookupObject('ce380ef0f10a85beb864025928e1819b')
<ATBTreeFolder at /test/events>

None will be returned if there is content item with matching UID (the item has been deleted).