Laravel 5 - 基于模型和相关的模型ID获得特定的多对多关系

Question

I've got Tag and Attendee Eloquent models, they are in many-to-many relation. Pivot table has also two more attributes – value_int and value_string. My Attendee model looks like this:

class Attendee extends Model
{
    public $timestamps = false;

    protected $fillable = [
        'event_id'
    ];

    public function tags() {
        return $this->belongsToMany('App\Models\Tag', 'attendee_tag', 'attendee_id', 'tag_id')
            ->withPivot(['value_string', 'value_int']);
    }

    public function scoreTagValue($tag_id) {
        return $this->tags->where('tag_id', '=', $tag_id)->first();
    }

}

What I want is to obtain pivot values based on Attendee model and variable tag_id, so I've written scoreTagValue function, but it always returns null and I don't know why :( I'm calling it this way: $attendee->scoreTagValue($tag_id). Thanks for your help :)

Answer 1

You need to access the relation, not the property:

public function scoreTagValue($tag_id) {
    return $this->tags()->where('tag_id', '=', $tag_id)->first();
}

Also, according to the docs, withPivot() does not take an array, so:

->withPivot('value_string', 'value_int');