Help:Property constraints portal/Required qualifiers

required qualifier constraint (Q21510856) specifies that some qualifier is required for this property. To limit the set of permitted qualifiers, use allowed qualifiers constraint.

For example, head of state (P35) statements should always have a start time (P580) qualifier.

If the property also has an allowed qualifiers constraint, all the required qualifiers must also be listed as permitted qualifiers there.

This constraint can only be checked on the main value of a statement; if any other constraint scope (P4680) is specified, an error is reported.

Possible actions

There are several possible ways to address a violation of this constraint:

• The most likely case is that the missing qualifier should be added. If the value is not known, it might make sense to use unknown value Help.
• It’s possible that the statement is a rare (but legitimate) exception to the constraint, and nothing should be done.

Parameters

This constraint has one mandatory parameter:

property (P2306)

Contains the required qualifier. Must contain exactly one property (no value Help or unknown value Help are not allowed). To add multiple required qualifiers, add multiple constraints of this type.

Examples

Example 1

Example setting for population (P1082).

property constraint	required qualifier constraint edit property point in time 0 references add reference
		add value

Example 2

Example setting for solubility (P2177).

property constraint	required qualifier constraint edit property solvent 0 references add reference required qualifier constraint edit property temperature 0 references add reference
		add value

Template

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 Template:Constraint, invoked from Template:Property documentation. Translations are defined at Module:i18n/constraints.

Required qualifier “determination method or standard (P459)”: this property should be used with the listed qualifier. (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/P1082#mandatory qualifier, SPARQL

Lists

Lists of properties which are set item required qualifier constraint.

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