Join only returning one row in getLoadSelect method rewrite

Question

I'm trying to load all of the associated entries to another table that has a foreign key

protected function _getLoadSelect($field, $value, $object)
{
    $field = $this->getConnection()->quoteIdentifier(sprintf('%s.%s', $this->getMainTable(), $field));

    $select = $this->getConnection()->select()->from($this->getMainTable())->where($field . '=?', $value)
    ->join(
        ['second_table_alias' => 'second_table'],
        'first_table.entity_id = second_table_alias.entity_id'
    )
    ->group('second_table_alias.entity_id');

    return $select;
}

There are multiple rows that share that entity_id and if I switch between left join and join (inner join) it returns different results.

Is it possible to get an array of all rows with that entity_id from the secondary table? What am I doing wrong?

Answer 1

The returned result needs to be fetched in order to retrieve the results:

$select = $entity->_getLoadSelect();
$data = $this->getConnection()->fetchAll($select);

Answer 2

There only reason (I see) to load all the associated entities when the load select is executed is to be able to apply a filter on those loaded entities.
If you apply a filter inside the load select that should get only one record (or none) it should be OK.
So you can apply your filter directly in this method.
Take a look at the method from the CMS module
If you just need the associated entities, I recommend you a separate method afterLoad for example, that will just query your secondary table and give you what you need.
Or better yet, have a method that retrieves the results when needed the first time, then stores them in a member variable.
This way you get lazy loading.