Mapping Question

jacklin · **Joined:** Fri May 23, 2008 4:39 pm **Posts:** 3

I need a little help with a mapping. Here are my tables and current mappings.

Teams:
TeamId

TeamGroups:
TeamGroupId
TeamId

TeamGroupMembers:
TeamGroupId
UserId

TeamGroupTeams
TeamGroupId
TeamId

If I want to get a specific team group its not a problem, but if I want to limit the number of teams that appear ( for pagination ) it won't work.
I think because hibernate doesn't exactly know how to go about it.

My TeamGroup mapping is:

<set name="teams" inverse="true" table="team_group_teams" >
<key>
<column name="team_group_id"></column>
</key>
<many-to-many class="Team" />
</set>
<set name="members" inverse="true" table="team_group_members" >
<key>
<column name="team_group_id"></column>
</key>
<many-to-many class="Users" />
</set>

So doing a:
Criteria crit = this.getSession().createCriteria(TeamGroup.class);
crit.setMaxResults(10);

Only knows to limit the number of TeamGroups returned, but not the
number of teams that belong to the group, which is what i'm after really.

What i'm trying to accomplish over all here is someone asks for a
group of teams ( like a division, or league ), and then I can
give the user a paginated list of those teams.

The feature is new so if there is a suggestion that means changing the table structure in some way I can do it without too much fuss.

I did my due diligence as far as researching the problem, but I haven't had much luck, and I've spent way too long on this as it is.

Any help would be great! Thanks so much!

jacklin · **Joined:** Fri May 23, 2008 4:39 pm **Posts:** 3

Well I fixed it. Not sure if its the best way or not but I'll share just in case it can help someone else. Bummer nobody responded at all to my post... not even to ask for more info. Any way here goes:

I put teamGroups in the teams class / mapping:

Code:

<set name="teamGroups" table="team_group_teams">
      <key column="team_id"/>
      <many-to-many class="com.ack.dreamjournal.bo.TeamGroup" column="team_group_id" />
</set>

Now I do a criteria query on the teams class instead of the
teamGroups class so the setMaxResults will limit what I want.

Code:

      
Criteria c = this.getSession().createCriteria( Team.class);
        c.createAlias("teamGroups", "dg");
   c.add(Restrictions.eq("dg.id", dg.getId() ));
   c.setFirstResult( startPage * teamsPerPage);
   c.setMaxResults(teamsPerPage);

The createAlias is needed so hibernate will join correctly.

It took 30 seconds to write the sql query to give me the results, and
about 5 hours in all to figure out how to make hibernate do it.

Ugh...

Cameron McKenzie · **Posted:** Sun May 25, 2008 2:47 pm

We all share your paint. :(

Thanks so much for posting back. Your hard work will inevitably help out someone else having the same problems. Good Karma to you!