Laravel polymorphic relationships return null - laravel

Question

I'm trying to join an Order and 2 different OrderDetailType tables.
OrderDetailType1
- id
- order_id
OrderDetailType2
- id
- order_id
Order
- id
- detail_type 'type1' or 'type2'
And I have followed Polymorphic Relations example in official Laravel site and adapted to my code like:
class OrderDetailType1 extends Model {
public function order() {
return $this->morphOne('App\Order', 'type_detail');
}
}
class OrderDetailType2 extends Model {
public function order() {
return $this->morphOne('App\Order', 'type_detail');
}
}
class Order extends Model {
public function type_detail() {
return $this->morphTo();
}
}
And I have put Relation::morphMap() into boot() function in AppServiceProvider class already.
use Illuminate\Database\Eloquent\Relations\Relation;
class AppServiceProvider extends ServiceProvider {
public function boot() {
Relation::morphMap([
'type1' => 'App\OrderDetailType1',
'type2' => 'App\OrderDetailType2'
]);
}
}
The example is different from my code. The difference is both foreign key and the attribute that specifying which table to be joined should be in Order. So I cannot use morphTo() and morphOne() like the example to solve this.
I am confuse which classes should contain morphTo() and morphOne(). And is there any overload to specify which table have foreign key and type?
I use Laravel 5.4. Thank You in Advance.

Answer 1

The _id column has to be in the Order table:
OrderDetailType1
- id
OrderDetailType2
- id
Order
- id
- detail_type
- detail_id
class OrderDetailType1 extends Model {
public function order() {
return $this->morphOne('App\Order', 'detail');
}
}
class OrderDetailType2 extends Model {
public function order() {
return $this->morphOne('App\Order', 'detail');
}
}
class Order extends Model {
public function detail() {
return $this->morphTo();
}
}