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Many-to-many relation with additional column

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sir-archimedes

Post subject: Many-to-many relation with additional column

Posted: Tue Oct 31, 2006 7:41 pm

Beginner

Joined: Mon Mar 20, 2006 7:59 am
Posts: 30

Hello,

I want to set up an user authorization system with NHibernate 1.2.0 beta1. I have two relevant classes (here in pseudo syntax):

Code:

class Permission
{
    [PrimaryKey]
    String InternalName{ get; set; }
    String ExternalName{ get; set; }
}

class UserGroup
{
    [PrimaryKey]
    int Id { get; set; }
    String Name { get; set; }
    IList<Permission> GrantedPermissions { get; set; }
    IList<Permission> RevokedPermissions { get; set; }
}

I was thinking of three tables: UserGroups, Permissions, UserGroups_Permissions.

UserGroup_Permissions should contain three columns: (PermissionInternalName, UserGroupId, PermissionType) where PermissionType = 'G' if and only if the permission was granted and PermissionType = 'R' if and only if the permission was revoked.

I tried this with:

Code:

      <bag name="GrantedPermissions" table="UserGroups_Permissions" where="PermissionType = 'G'">
         <key column="UserGroupId" />
         <many-to-many class="Permission" column="PermissionInternalName" />         
      </bag>

Is this scenario possible or do I need two relation tables?

Regards and thanks in advance,
Dominik

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anuarneto

Post subject:

Posted: Wed Nov 01, 2006 7:57 am

Beginner

Joined: Fri Oct 20, 2006 8:02 am
Posts: 36

I think You should do something like this:

Code:

<bag
   name='Permissions'
   cascade='all'
   lazy='true'
   inverse='false'
   table='UserGroups_Permissions'
   >
   <key column='UserGroupId' foreign-key='UserGroups' />
   <composite-element class='UserGroups_Permissions' >
      <many-to-one
         name='Permission'
         column='PermissionInternalName'
         class='Permission'
         not-null='true'
      />
      <property name='PermissionType' column='PermissionType' type='Char' />
   </composite-element>
</bag>

and then build your two lists going throw this whole one.

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sir-archimedes

Post subject:

Posted: Sun Nov 12, 2006 11:11 am

Beginner

Joined: Mon Mar 20, 2006 7:59 am
Posts: 30

Thank you for this tip, that did the trick :-)

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crazypotato

Post subject:

Posted: Thu Dec 14, 2006 9:16 pm

Newbie

Joined: Wed Dec 13, 2006 11:57 pm
Posts: 6

What you are doing very similar to what i did. I will put it in the context of your provided example to illustration the problem I am having. Basically, if you navigate from UserGroup to get UserGroups_Permissions, the composite-id in UserGroups_Permissions class will be empty.

I'm using NH 1.0.3. I suspect it is a bug. Can someone confirm it?

Thanks.

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martbl

Post subject:

Posted: Mon Dec 18, 2006 3:24 pm

Regular

Joined: Fri Feb 03, 2006 5:28 pm
Posts: 73
Location: Québec, QC, Canada

anuarneto wrote:

I think You should do something like this:

Code:

<bag
   name='Permissions'
   cascade='all'
   lazy='true'
   inverse='false'
   table='UserGroups_Permissions'
   >
   <key column='UserGroupId' foreign-key='UserGroups' />
   <composite-element class='UserGroups_Permissions' >
      <many-to-one
         name='Permission'
         column='PermissionInternalName'
         class='Permission'
         not-null='true'
      />
      <property name='PermissionType' column='PermissionType' type='Char' />
   </composite-element>
</bag>

and then build your two lists going throw this whole one.

could you explain your mapping.. I have a very very similar situation.. and I'd like to understand what I'm about to do ! :)

Thanks

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