Help:Property constraints portal/Type
type constraint (Q21503250) specifies that items with a given property should have a given type. This is also known as the domain of a property.
Subclass relations according to subclass of (P279) are taken into account: if a constraint demands that an item should be an instance of building (Q41176), it is not a violation if the item is an instance of skyscraper (Q11303), because there is a subclass of (P279) path from skyscraper (Q11303) to building (Q41176). (If an indirect relation should not be permitted, item requires statement constraint (Q21503247) can be used.)
There are several possible ways to address a violation of this constraint:
- It’s possible that the item should not have the statement at all, and that the statement should be removed.
- It’s possible that the item is missing the right instance of (P31) or subclass of (P279) statement.
- It’s possible that the item has the right instance of (P31) or subclass of (P279) statement, but the linked item is missing a subclass of (P279) statement. For example, if an item with population (P1082) was instance of (P31) big city (Q1549591), but big city (Q1549591) was missing subclass of (P279) city (Q515), then this could result in a violation on the item even though the error is actually on big city (Q1549591).
- It’s possible that the item is a rare, but legitimate exception to the constraint, and nothing should be done.
This constraint has two parameters (both mandatory):
- relation (P2309)
- Either instance of (Q21503252) or subclass of (Q21514624). Describes whether the item should be an instance or a subclass of the class. This parameter must only be given once.
- class (P2308)
- Lists the classes that the item should have. Each class must be an item ID (no value Help or unknown value Help is not permitted).