Edges
Edges are documents with special _from
and _to
attributes to reference other documents by their ID to form a graph
Edges are used in graphs to link vertices together.
They are documents with two additional system attributes that you set, a
_from
and a _to
attribute. They need to be stored in edge collections.
Together with vertex documents stored in document collections (also called vertex collections in this context), edges form graphs.
Example
- An edge collection stores the information that a company’s reception is a
sub-unit to the services unit and the services unit is sub-unit to the
CEO. You would express this relationship with the
_from
and_to
attributes. - A vertex collection stores all the properties about the reception, for example, that 20 people are working there, the room number, and so on.
- The
_from
attribute of an edge is the document ID of the linked vertex (incoming relation). - The
_to
attribute of an edge is the document ID of the linked vertex (outgoing relation).
Edges API
Edges are normal documents
but additionally have a _from
and a _to
attribute that you need to set.
You can update the _from
and _to
attributes like any other document attribute.