doctrine2/manual/docs/Working with objects - Component overview - Collection - Key mapping.php

Sometimes you may not want to use normal indexing for collection elements. For example in
some cases mapping primary keys as collection keys might be useful. The following example
demonstrates how this can be achieved.

<code type="php">
// mapping id column

$user = new User();

$user->setAttribute(Doctrine::ATTR_COLL_KEY, 'id');

// now user collections will use the values of
// id column as element indexes

$users = $user->getTable()->findAll();

foreach($users as $id => $user) {
    print $id . $user->name;
}

// mapping name column

$user = new User();

$user->setAttribute(Doctrine::ATTR_COLL_KEY, 'name');

// now user collections will use the values of
// name column as element indexes

$users = $user->getTable()->findAll();

foreach($users as $name => $user) {
    print $name . $user->type;
}
</code>