Help:属性约束门户/值类型约束

value-type constraint (Q21510865)定义了一个特定属性应当具有一种特定类型。这也称为属性的“范围”。

例如，mother (P25)的值应当是instance of (P31)human (Q5)或animal (Q729)，space launch vehicle (P375)的值应当是subclass of (P279)launch vehicle (Q697175)。

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, value-requires-statement constraint (Q21510864) can be used.) Longish paths sometimes time-out and don't work in all tools.

如果未指定constraint scope (P4680)，則會在任何位置檢查此約束。

可能的动作

有幾種方法可以解決違反此約束的問題：

• 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 value is missing the right instance of (P31) or subclass of (P279) statement.
• It’s possible that the value 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 had space launch vehicle (P375)Ariane 1 (Q18375), and the statement Ariane 1 (Q18375)subclass of (P279)Ariane (Q131535) existed, but the statement Ariane (Q131535)subclass of (P279)launch vehicle (Q697175) was missing, then this could result in a violation even though the error is actually neither on the item with the violation, nor on the linked value Ariane 1 (Q18375), but on Ariane (Q131535).
• It’s possible that the item is a rare, but legitimate exception to the constraint, and nothing should be done.

参数

这种约束有两种参数（都是强制的）：

relation (P2309)

Must be instance of (Q21503252), subclass of (Q21514624), or instance or subclass of (Q30208840). Describes whether the item should be an instance of the class(es), or a subclass of it/them, or whether both are allowed. This parameter must only be given once.

class (P2308)

Lists the classes that are allowed for the value. Each class must be an item ID (no value Help or unknown value Help is not permitted). If more than one class is specified, the constraint is satisfied as long as the value has at least one of these types.

示例

例子1

adjacent station (P197)的值必须是station (Q719456)的实例

property constraint	value-type constraint edit class station relation instance of 0 references add reference
		add value

例子2

space launch vehicle (P375)的值必须是launch vehicle的子类

property constraint	value-type constraint edit class launch vehicle relation subclass of 0 references add reference
		add value

模板

When the constraint is set to the property, the following template is automatically displayed in the property talk page. The template is created by Module:Constraints using {{Constraint}}, invoked from {{Property documentation}}. Translations are defined at Module:i18n/constraints.

Value type “entry point (Q228332), proposed railway station (Q28109487)”: This property should use items as value that contain property “instance of (P31)”. On these, the value for instance of (P31) should be an item that uses subclass of (P279) with value entry point (Q228332), proposed railway station (Q28109487) (or a subclass thereof). (Help)

Exceptions are possible as rare values may exist. Exceptions can be specified using exception to constraint (P2303).
List of violations of this constraint: Database reports/Constraint violations/P197#Value type Q228332, Q28109487, SPARQL

列表

Lists of properties which are set value type constraint.

• Category:Properties with value only constraints
• SPARQL query - click the execute button at the linked page to see the query result.