Level 13
Have you found a solution yet for your problem, because I'm facing the same problem..
Mar 12, 2015
13
Level 1
Laravel 5 - Eloquent Models Inheritance (Accessing columns from abstract parent class in derived classes)
Hello.
I'm working on a little project and ran across a problem. (See the ERD for the design).
I want to, for example, access the "name" of the creatures table in the Monster Context.
abstract class Creature extends Model {...}
class Character extends Creature {...}
class Monster extends Creature {...}
If I don't make the parent class (Creature) abstract, I can do a workaround like this:
class Monster extends Creature {
public function getStatblock() {
return parent::getStatblock();
}
}
class Creature extends Model {
public function getStatblock() {
$statblock = [];
$statblock["name"] = $this->creature->name;
return $statblock;
}
}
As you can see, I have to resolve the FK of the derived class in the parent class, to get to the actual instance of the object. It looks really odd though and I want to have something more elegant.
edit: I do not want to use single table inheritance unless I really have to. I would like to maintain a one table per class design.
Level 8
I am not sure about declaring the parent class as abstract is going to help you. Did you look into Polymorphic Relations in Laravel. I think it can solve your problem.
You can find the official documentation here: http://laravel.com/docs/5.1/eloquent-relationships#polymorphic-relations
Here is a broad analysis on polymorphic relations: http://richardbagshaw.co.uk/laravel-user-types-and-polymorphic-relationships/
1 like
Level 2
I'm facing the same problem.
If I use Polymorphic Relations, I have to insert the ID of the sub tables into the parent table. In this scenario, the Monster and Character tables will not have the "creature_id" anymore. It does no sense for me. Any sugestion?
Level 4
@andreza.vieira what if you abstract the foreign key? Whenever I use polymorphic relations, I don't use the standard naming convention that Laravel uses, I always switch it to "parent" (thus making the linkage with "parent_id" and "parent_type").
Level 2
@kobear , thanks for the answer. I think I did not understand... Can I use polymorphic relation and insert the parent_id into the sub tables (subclasses)? For example, I would have the tables:
- Creature (id, name, aligment, hitdice) - without the "type_id" and "ability_id"
- Monster (id, creature_id, size_id)
- Character (id, creature_id, race_id)
Thanks.
Level 4
Yes, that would work. Monster and Character would each need to have the relationship like below:
public function creature()
{
return $this->hasOne(Creature::class);
}
Level 2
@kobear I will try, thanks. In this case, is it possible a Creature be a Monster and a Character at the same time? I'm asking because in my project I need something like this.
Level 4
Yes, that is exactly what it can do.
Level 2
I'm having problems to insert the data into the database. I have to: (1) save the Creature; (2) get the last inserted id from Creature; (3) save the Monster with the "creature_id" and other fields. Is it correct?
I noted that Laravel sugest another way (https://laravel.com/docs/5.1/eloquent-relationships#inserting-related-models). Which is the best way?
Level 2
@kobear. Suppose that a Creature has a relationship with the Address table. How to access the address street (field from Address) from a Monster?
I will call getRelations function from the Monster to obtain the Creature. After I will call getRelations from the Creature to obtain the Address. Finnally, I will obtain the street from the Address. I did this way, but my relations are empty. I do not know how to implement the all() function to do all the joins with the tables.
Any suggestion will help. Thanks.
Level 4
Keep in mind that if your Creature->Monster is a hasMany relationship , it is going to return a collection. So, if you try to get the address by using
$monster = App\Monster::find('Dracula');
$monster->creature->address;
will return null because $monster->creature is an array. It should be done via referencing the array element
$monster = App\Monster::find('Dracula');
$monster->creature[0]->address;
Level 1
It's an old thread but could be of help to STI searchers. https://github.com/calebporzio/parental
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