Laravel Eager Loading Polymorphic Relationships

问题

Trying to eager load a model and it's related model but the related model returns null even though it has related data.

Group Model is polymorphic 1:1 to either Game or Gamer.

Group Model Relationship:

public function groupable()
{
    return $this->morphTo();
}

Game Model Relationship:

public function group()
{
    return $this->morphOne('Group', 'groupable');
}

Gamer Model Relationship:

public function group()
{
    return $this->morphOne('Group', 'groupable');
}

Query to Load Group then Game:

$group = Group::whereSubdomain($id)->first();
$game = $group->game;

Group returns the group but game returns null.

Here is a sample database entry for Groups table:

id    subdomain    groupable_id    groupable_type
5     Starmade     10              Game

Here is a sample database entry for Games table:

id    genre    rating
10    7        4.5

Not sure where I am going wrong to have no game returned.

回答1:

Try this. It might help.

    public function groupable()
{
    return $this->morphTo('groupable');
}

I had that problem too earlier, maybe you have the same prob like me. Essentially what I did was to help Laravel finds what columns it needs to look up for.

来源：https://stackoverflow.com/questions/21487145/laravel-eager-loading-polymorphic-relationships