Declares a link type in the graph’s ontology: a name, its source and target object types, an optional cardinality hint (for example many-to-one), and property definitions. Source and target must name declared object types by the time the ontology is frozen. After freezing, this command fails with failed_precondition.engine.graph_ontology_frozen.

Successful mutations return an acknowledgement that identifies the affected target, the mutation effect, and commit facts when the operation changed stored state.

Examples

Define a link (edge) type between two object types.

CLI

$ strata graph create g
$ strata graph ontology define-object-type g person
$ strata graph ontology define-link-type g knows person person
$ strata graph ontology get g

Wire

{"graph":"g","type":"graph_create"}
{"graph":"g","name":"person","type":"graph_define_object_type"}
{"graph":"g","name":"knows","source":"person","target":"person","type":"graph_define_link_type"}
{"graph":"g","type":"graph_get_ontology"}

Parameters

Name	Type	Required	Description
cardinality	string	no	Optional cardinality hint (e.g. one-to-many).
graph	string	yes	Graph name.
name	string	yes	Link type name.
properties	object	no	Declared properties by name.
source	string	yes	Declared source object type.
target	string	yes	Declared target object type.

Plus the optional scope: branch and space (default to the session branch and the "default" space).

Returns

MutationAck<GraphOntologyWrite>.

Errors

• failed_precondition.engine.runtime_closed
• not_found.engine.branch
• invalid_argument.engine.product_space
• invalid_argument.engine.graph_name
• not_found.engine.graph
• invalid_argument.engine.graph_type_name
• invalid_argument.engine.graph_type_name_reserved
• invalid_argument.engine.graph_property_name
• failed_precondition.engine.graph_ontology_frozen

Invocation

• CLI: strata graph ontology define-link-type
• Wire type: graph_define_link_type