Question

I can’t find a way to use findOrCreate() with single inheritance and abstract parent class in Propel. This little example gives me a fatal error:

Fatal error: Cannot instantiate abstract class ComicBook
propel\query\ModelCriteria.php on line 1181

The query that throws this fatal error is fairly simple:

$thebook = ComicBookQuery::create()->filterById(1)->findOneOrCreate();

A little piece of database schema:

<table name="book" abstract="true" phpName="AbstractBook">
    <column name="id" type="INTEGER" required="true"
       primaryKey="true" autoIncrement="true"/>
    <column name="type" type="VARCHAR" size="255" required="true"
       inheritance="single">
        <inheritance key="Abstract" class="AbstractBook"/>
        <inheritance key="ComicBook" class="ComicBook" extends="AbstractBook"/>
    </column>
</table>

Is there any way to get inheritance working with abstract parent class?

Answer 1

The main issue with the single table inheritance is that you always fake things. You get this error because the real model is AbstractBook, nothing else…

With abstract=false, you’ll be able to instanciate an AbstractBook (which won’t be abstract at all…), and then it will be transformed into a ComicBook.

By setting abstract=true, you cannot instantiate an AbstractBook. Overriding to the rescue!

I didn’t dig a lot in the code but, if you want to create ComicBook with findOneOrCreate(), you’ll have to override the following method: getModelName() in your ComicBookQuery class:

<?php

class ComicBookQuery extends BaseComicBookQuery {

    public function getModelName()
    {
        return 'ComicBook';                                                                                                                              
    }

} // ComicBookQuery

It’s a best practice to override methods to fit your needs 😉