Lets say that we have a query like this one:
SELECT *, (CUSTOM_EXPRESSION) as virtualfield FROM users
The user's entity itself has the "virtualfield" but the mapping annotations no, since the table doesn't have this field.
Assuming that it is executed as a raw SQL, how do we populate the entity with the field above?
I've found the answer. To do so, you need to use a scalar value. For instance:
$rsm = new \Doctrine\ORM\Query\ResultSetMappingBuilder($this->getEntityManager());
$rsm->addRootEntityFromClassMetadata('Category', 'c');
$rsm->addScalarResult('depth', 'depth');
// [ ... ]
$results = $q->execute();
// Output will be a two-dimensional array
// array(0 => array(0 => CategoryObject, 'depth' => 'scalar-value', // ... ), // ...)
Then, you can loop through it and set the property on the object if you want.