With this option you would store into the entity itself the association information ?
Something like:
City:
{_id: "ParisID", name:"Paris"}
{_id: "StrasbourgID", name:"Strasbourg"}

Country
{
_id: ObjectID("123151231313123"),
name:"France",
cities:{["ParisID", "StrasbourgID"]}
}

This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators.
For more information on JIRA, see: http://www.atlassian.com/software/jira