The PROPERTY_CONSTRAINT_SCHEMA schema type defines constraint definitions that can be assigned to a property using the Constraint schema property.

Naming convention

To easily identify pages that contain a constraint schema it is suggested to use smw/schema:Constraint:... as naming convention.

Properties

• type defines the type and is fixed to PROPERTY_CONSTRAINT_SCHEMA
• constraints the section that contains constraints definitions
• tags simple tags to categorize a schema

Example

{
    "type": "PROPERTY_CONSTRAINT_SCHEMA",
    "constraints": {
        ...
    },
    "tags": [
        "property constraint",
        "..."
    ]
}

Constraint properties

• allowed_namespaces (array) specifies allowed namespaces
• unique_value_constraint (boolean) specifies that values should be unique across the wiki, that the value is likely to be different (distinct) from all other items
• https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/master/docs/examples/constraint.schema.md "`single_value_constraint`" (boolean) specifies that the property expects only a single value per assigned entity
• https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/master/docs/examples/register.custom.constraint.md "`custom_constraint`" (object) specifies non-schema specific custom constraints implementations
• https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/master/docs/examples/constraint.schema.md "`non_negative_integer`" (boolean) specifies that values are derived from integer with the minimum inclusive to be 0
• https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/master/docs/examples/constraint.schema.md "`must_exists`" (boolean) specifies that the annotated value must exist to be valid

Extending constraints

• General introduction on how to extend a https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/master/docs/architecture/extending.constraint.md "constraint"
• How to register a https://github.com/SemanticMediaWiki/SemanticMediaWiki/blob/master/docs/examples/register.custom.constraint.md "custom constraint" using the custom_constraint property

Validation

/data/schema/property-constraint-schema.v1.json