Laravel Eloquent: multiple foreign keys for relationship

Question

I am in the process of porting a project to Laravel.

I have two database tables which are in a One-To-Many relationship with each other. They are joined by three conditions. How do I model this relationship in Eloquent?

I am not supposed to modify the database schema, since it has to remain backwards compatible with other things.

I have tried the following, but it doesn't work.

The owning side:

use Illuminate\Database\Eloquent\Model;

class Route extends Model
{
    public function trips()
    {
        return $this->hasMany('Trip', 'route_name,source_file', 'route_name,source_file')
    }
}

The inverse side:

use Illuminate\Database\Eloquent\Model;

class Trip extends Model
{
    public function routes()
    {
        return $this->belongsTo('Route', 'route_name,source_file', 'route_name,source_file');
    }
}

Example Route database values:

id    | route_name     | source_file
---------------------------------------
1     | Berlin - Paris | file1.xls   
2     | Madrid - London| file2.xls
3     | Berlin - Paris | file3.xls

Example Trip database values:

id        | route_name           | source_file | duration
---------------------------------------------------------
1         | Berlin - Paris       | file1.xls   | 78
2         | Madrid - London      | file2.xls   | 241
3         | Berlin - Paris       | file3.xls   | 65
1         | Berlin - Paris       | file1.xls   | 95
1         | Berlin - Paris       | file1.xls   | 65

Route and Trip have other attributes, which I did not include here for brevity.

Is this possible in Eloquent?

Answer 1

I had to deal with a similar problem. The solution provided by @fab won't work with eager loading because $this->source_file would be null at the time the relationship is processed. I came up with this solution

After installing Compoships and configuring it in your models, you can define your relationships matching multiple columns.

The owning side:

use Illuminate\Database\Eloquent\Model;
use Awobaz\Compoships\Compoships;

class Route extends Model
{
    use Compoships;

    public function trips()
    {
        return $this->hasMany('Trip', ['id', 'route_name', 'source_file'], ['route_id', 'route_name', 'source_file']);
    }
}

The inverse side:

use Illuminate\Database\Eloquent\Model;
use Awobaz\Compoships\Compoships;

class Trip extends Model
{
    use Compoships;

    public function route()
    {
        return $this->belongsTo('Route', ['route_id', 'route_name', 'source_file'], ['id', 'route_name', 'source_file']);
    }
}

Compoships supports eager loading.

Answer 2

As Jonathon already mentioned, you could try to add an where-clause to your relationship:

use Illuminate\Database\Eloquent\Model;

class Route extends Model
{
    public function trips()
    {
        return $this->hasMany('Trip', 'route_name')->where('source_file', $this->source_file);
    }
}

The inverse side:

use Illuminate\Database\Eloquent\Model;

class Trip extends Model
{
    public function routes()
    {
        return $this->belongsTo('Route', 'route_name')->where('source_file', $this->source_file);
    }
}