Muliple Collection Mapping Help Needed

Shurgot · **Joined:** Thu May 25, 2006 7:16 pm **Posts:** 2

Hibernate version:
3.1.3

I need some help mapping two collections of the same entity to one class. I have a parent table called Game. Game has several fields including two foreign keys, HomeTeamId and AwayTeamId. There is another table called Roster. Roster has a RosterId, GameId, TeamId and PlayerId field. The Roster table defines which Players are playing on what teams in a given Game.

I want to have two collections (properties) in my Game class. One called homeTeamRoster, the other called awayTeamRoster. I want to fill these bags with the entities in the Roster table based on the corresponding HomeTeamId and AwayTeamId values.

Example:

(Assuming Game.homeTeamRoster and Game.awayTeamRoster are List classes)

homeTeamRoster would contain all entities that have Roster.GameId = Game.GameId AND Roster.TeamId = Game.HomeTeamId

awayTeamRoster would contain all entities that have Roster.GameId = Game.GameId AND Roster.TeamId = Game.AwayTeamId

Any help would be appreciated.

Thanks!

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I'm presuming that Team and Player are only ever in unidirectional relationships: Teams don't know what Games they're involved in, you need Rosters to figure that out. You can arrange bidirectional relationships, but the mapping is more complex. If you want to do that, check out ternary associations, ref docs section 6.3.4.

Start with this, see what breaks...

Code:

<class name="Roster" ...>
  ...
  <many-to-one name="Team" class="Team" column="TeamID"/>
  <many-to-one name="Game" class="Game" column="GameID"/>
  <set name="Players" ...>
    ...
    <many-to-many class="Player" column="PlayerID" .../>
  </set>
  ...
</class>

<class name="Game" ...>
  ...
  <properties name="HomeTeamRosterID" insert="false" update="false" unique="true">
    <property column="HomeTeamID" name="HomeTeamID"/>
    <property column="GameID" name="GameID"/>
  </properties>

  <set name="HomeTeamRoster" ...>
    <key property-ref="HomeTeamRosterID">
      <column name="HomeTeamID"/>
      <column name="GameID"/>
    </key>
    <one-to-many class="Roster"/>
  </set>

  <properties name="AwayTeamRosterID" insert="false" update="false" unique="true">
    <property column="AwayTeamID" name="AwayTeamID"/>
    <property column="GameID" name="GameID"/>
  </properties>
  <set name="AwayTeamRoster" ...>
    <key property-ref="AwayTeamRosterID">
      <column name="AwayTeamID"/>
      <column name="GameID"/>
    </key>
    <one-to-many class="Roster"/>
  </set>
  ...
</class>