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doctrine2/manual/new/docs/en/object-relational-mapping/relations/join-table-associations.txt
jepso 5329c3827c * Converted most of the docs to the new format.
* Fixed a few layout bugs in new documentation
* Fixed documentation table of contents indentation bug in IE6 (fixes #344)
* Fixed a parser bug in Sensei_Doc_Section
* Restructrured a bit some files of the documentation.
2007-06-13 21:30:32 +00:00

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++++ One-to-One
++++ One-to-Many, Many-to-One
++++ Many-to-Many
If you are coming from relational database background it may be familiar to you how many-to-many associations are handled: an additional association table is needed.
In many-to-many relations the relation between the two components is always an aggregate relation and the association table is owned by both ends. For example in the case of users and groups when user is being deleted the groups it belongs to are not being deleted and the associations between this user and the groups it belongs to are being deleted.
Sometimes you may not want that association table rows are being deleted when user / group is being deleted. You can override this behoviour by setting the relations to association component (in this case {{Groupuser}}) explicitly.
In the following example we have Groups and Users of which relation is defined as many-to-many. In this case we also need to define an additional class called {{Groupuser}}.
<code type="php">
class User extends Doctrine_Record {
public function setUp() {
$this->hasMany('Group','Groupuser.group_id');
}
public function setTableDefinition() {
$this->hasColumn('name','string',30);
}
}
class Group extends Doctrine_Record {
public function setUp() {
$this->hasMany('User','Groupuser.user_id');
}
public function setTableDefinition() {
$this->hasColumn('name','string',30);
}
}
class Groupuser extends Doctrine_Record {
public function setTableDefinition() {
$this->hasColumn('user_id','integer');
$this->hasColumn('group_id','integer');
}
}
$user = new User();
// add two groups
$user->Group[0]->name = 'First Group';
$user->Group[1]->name = 'Second Group';
// save changes into database
$user->save();
// deleting the associations between user and groups it belongs to
$user->Groupuser->delete();
$groups = new Doctrine_Collection($conn->getTable('Group'));
$groups[0]->name = 'Third Group';
$groups[1]->name = 'Fourth Group';
$user->Group[2] = $groups[0];
// $user will now have 3 groups
$user->Group = $groups;
// $user will now have two groups 'Third Group' and 'Fourth Group'
</code>
++++ Self-referencing
Self-referencing with join tables is done as follows:
<code type="php">
class User extends Doctrine_Record {
public function setUp() {
$this->hasMany('User as Friend','UserReference.user_id-user_id2');
}
public function setTableDefinition() {
$this->hasColumn('name','string',30);
}
}
class UserReference extends Doctrine_Record {
public function setTableDefinition() {
$this->hasColumn('user_id','integer');
$this->hasColumn('user_id2','integer');
}
}
</code>