Imagine a user being part of different groups.
A group can have different roles, and a user can be part of different groups.
He also can have different roles in different groups apart from the membership.
The association of a User, a Group and a Role can be referred to as a HyperEdge.
However, it can be easily modeled in a property graph as a node that captures this n-ary relationship, as depicted below in the U1G2R1 node.
Graph
To find out in what roles a user is for a particular groups (here Group2), the following Cypher Query can traverse this HyperEdge node and provide answers.
Query
START n=node:node_auto_index(name = "User1") MATCH n-[:hasRoleInGroup]->hyperEdge-[:hasGroup]->group, hyperEdge-[:hasRole]->role WHERE group.name = "Group2" RETURN role.name
The role of User1:
Here, find all groups and the roles a user has, sorted by the roles names.
Query
START n=node:node_auto_index(name = "User1") MATCH n-[:hasRoleInGroup]->hyperEdge-[:hasGroup]->group, hyperEdge-[:hasRole]->role RETURN role.name, group.name ORDER BY role.name asc
The groups and roles of User1
Assume you have a more complicated graph:
- 2 user nodes User1, User2
- User1 is in Group1, Group2, Group3.
- User1 has Role1, Role2 in Group1; Role2, Role3 in Group2; Role3, Role4 in Group3 (hyper edges)
- User2 is in Group1, Group2, Group3
- User2 has Role2, Role5 in Group1; Role3, Role4 in Group2; Role5, Role6 in Group3 (hyper edges)
The graph for this looks like the following (nodes like U1G2R23 representing the HyperEdges):
Graph
To return Group1 and Group2 as User1 and User2 share at least one common role in those 2 groups, the cypher query looks like:
Query
START u1=node:node_auto_index(name = "User1"),u2=node:node_auto_index(name = "User2")
MATCH u1-[:hasRoleInGroup]->hyperEdge1-[:hasGroup]->group,
hyperEdge1-[:hasRole]->role,
u2-[:hasRoleInGroup]->hyperEdge2-[:hasGroup]->group,
hyperEdge2-[:hasRole]->role
RETURN group.name, count(role)
ORDER BY group.name ascThe groups where User1 and User2 share at least one common role: