Eloquent ORM / Laravel - use custom pivot table structure

eloquent, laravel, many-to-many, pivot

Solution

`belongsToMany` would accept 3rd and 4th arguments. You can see it in documentation: http://laravel.com/docs/eloquent#relationships

But the thing that is not in documentation is that you can constraint your relation by chaining the query builder functions like `where`, `orderBy` etc.

So your code would be something like:

class Type extends Eloquent {

    public function units()
    {
        return $this->belongsToMany('Unit', 'relations', 'first_id', 'second_id')
          ->withPivot(['relation_type'])
          ->where('relations.relation_type', '=', 'type_unit');
    }

}

Problem

I'm trying to build a Laravel app using a customized database structure. I have tables `types`, `units`, `content`, and a pivot table called `relations`. The structure of the `relations` table is such: ``` --------------------------------------------- | id | relation_type | first_id | second_id | --------------------------------------------- | 1 | type_unit | 1 | 2 | --------------------------------------------- | 2 | unit_content | 2 | 3 | --------------------------------------------- ``` In other words, the first three tables have many-to-many relations among themselves, and the fourth one is the pivot table for all the relations. How can I use the Eloquent's `BelongsToMany` method with this pivot table structure, i.e. how can I select only the pivot table's records relevant to the given relation? For example, how would I use only the type_unit relations in this: ``` class Type extends Eloquent { public function units() { return $this->belongsToMany('Unit', 'relations'); } } ``` but at the same time ignore the unit_content relations?

Original source