Edges

An edge is a labeled connection between two resources.

The edge table defines these relations between resources. It does this by adding a directed edge from one rsc record (subject) to another (object). It also adds a reference to the predicate: the label of the edge.

In the admin, edges are represented in the “Page connections” sidebar panel, of the edit page of the subject: the resource where the edges originate. By convention, edges are said to belong to their subject. This is to simplify the access control: if you are allowed to edit the resource, you’re also allowed to edit its outgoing edges (“Page connections” in the admin), creating connections to other resources.

See also

m_edge

Predicate

Edges have a label: like in The datamodel by example, author is a predicate of an edge which denotes that a certain article was written by a certain person

Just like categories, these predicates are themselves also resources: allowing you to specify metadata, give them a meaningful title, et cetera.

Each predicate has a list of valid subject categories and valid object categories (stored in the predicate_category table). This is used to filter the list of predicates in the admin edit page, and also to filter the list of found potential objects when making a connection. On their edit page in the admin interface, you can edit the list of valid subject and object categories for a predicate.

See also

m_predicate