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.
To find out in what roles a user is for a particular groups (here Group2), the following query can traverse this HyperEdge node and provide answers.
Query.
MATCH ({ name: 'User1' })-[:hasRoleInGroup]->(hyperEdge)-[:hasGroup]->({ name: 'Group2' }),
(hyperEdge)-[:hasRole]->(role)
RETURN role.name
The role of User1 is returned:
Here, find all groups and the roles a user has, sorted by the name of the role.
Query.
MATCH ({ name: 'User1' })-[:hasRoleInGroup]->(hyperEdge)-[:hasGroup]->(group),
(hyperEdge)-[:hasRole]->(role)
RETURN role.name, group.name
ORDER BY role.name ASC
The groups and roles of User1 are returned:
Assume a more complicated graph:
-
Two user nodes
User1,User2. -
User1is inGroup1,Group2,Group3. -
User1hasRole1,Role2inGroup1;Role2,Role3inGroup2;Role3,Role4inGroup3(hyper edges). -
User2is inGroup1,Group2,Group3. -
User2hasRole2,Role5inGroup1;Role3,Role4inGroup2;Role5,Role6inGroup3(hyper edges).
The graph for this looks like the following (nodes like U1G2R23 representing the HyperEdges):
To return Group1 and Group2 as User1 and User2 share at least one common role in these two groups, the query looks like this:
Query.
MATCH (u1)-[:hasRoleInGroup]->(hyperEdge1)-[:hasGroup]->(group),(hyperEdge1)-[:hasRole]->(role), (u2)-[:hasRoleInGroup]->(hyperEdge2)-[:hasGroup]->(group),(hyperEdge2)-[:hasRole]->(role) WHERE u1.name = 'User1' AND u2.name = 'User2' RETURN group.name, count(role) ORDER BY group.name ASC
The groups where User1 and User2 share at least one common role: