unable to create more than 2 same relations between two nodes

Question

Spent multiple days trying to figure out why this isn't working. My model is Player-[:PLAYED_WITH_TEAM]->team-[:CONTESTED_IN]->league. Few instances of this relation is as follows

bob-[:PLAYED_WITH_TEAM]->falcons-[:CONTESTED_IN]->ABC League
alice-[:PLAYED_WITH_TEAM]->falcons-[:CONTESTED_IN]->ABC League
bob-[:PLAYED_WITH_TEAM]->falcons-[:CONTESTED_IN]->XYZLeague

Bob played for the same team "Falcons" in two leagues ABC and XYZ. This is the fact i want to capture. Since Bob played for the same team in 2 different leagues, I need to have two PLAYED_WITH_TEAM relations between the same start (Bob) and end (Falcons) nodes.

I am using spring data and have the entities defined. I am able to create 2 such relationships but not more than two using spring data. i.e. if bob played for the same team Falcons for another 3rd league, I am unable to create that 3rd relation. I am not sure where the problem is. Below is my code for creating the new relation. PlayedWith is a RelationshipEntity with Player as the start node and Team as the end node.

private PlayedWith createPlayedWithRelation(League currentLeague, Team team, Player p)
    {
        System.err.println("Creating PLAYED_WITH_TEAM relation between " + team + " and " + p + " and " + currentLeague);

        PlayedWith playedWith = template.createRelationshipBetween(p, team, PlayedWith.class, "PLAYED_WITH_TEAM", true);
        playedWith.setDuring(currentLeague.getStartDate());
        playedWith.setInLeague(currentLeague);
        playedWith.setPlayer(p);
        playedWith.setTeam(team);
        playedWith.setAsCaptain(p.isCaptain());

        team.addPlayer(p);
        template.save(playedWith);

        return playedWith;
    }

PlayedWith

@RelationshipEntity (type = "PLAYED_WITH_TEAM")
public class PlayedWith
{
    @GraphId
    private Long nodeId;

    @StartNode
    Player player;

    @Fetch
    @EndNode
    Team team;
}

Let me know if there is an alternate way of storing this scenario.

score 0 · Answer 1 · answered Aug 23 '13 at 10:34

0

You do not need to add another relationship between bob and the falcons but between the falcons and the new league like this:

(falcons)-[:CONTESTED_IN]->(NEWLeague)

As bob plays for the falcons and the falcons then contested in ABC League, XYZ League and NEW League bob implicitly plays in those three leagues.

answered Aug 23 '13 at 10:34

Henrik Sachse

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This was my initial model but this approach has a drawback. How can you find the players of Falcon who only played XYZ league? A Player might not play all the leagues. – Aravind Yarram Aug 23 '13 at 11:13
Then you need an other relation from the player to the league in addition. – Henrik Sachse Aug 23 '13 at 11:40

score 0 · Answer 2 · answered Aug 29 '13 at 12:10

Actually there should only be one :PLAYED_WITH_TEAM relationship between bob and the falcons. Are you sure that you query is right for getting the amount of :PLAYED_WITH_TEAM relationships between Bob and the falcons?

From the SDN reference documentation:

Note

Spring Data Neo4j ensures by default that there is only one relationship of a given type between any two given entities. This can be circumvented by using the createRelationshipBetween() method with the allowDuplicates parameter on repositories or entities.

unable to create more than 2 same relations between two nodes

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