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.
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 is returned:
Here, find all groups and the roles a user has, sorted by the name of the role.
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 are returned:
Assume a more complicated graph:
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):
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.
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 ASC
The groups where User1 and User2 share at least one common role:
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