Laravel 4多对多三角形与Eloquent，检索“建议”类似的数据

This might be very simple, but I can't find the solution... Any help will be appreciated. I have 3 tables: users, skills and projects, all connected to each other with Many to Many relationship.

users <-- MtM --> skills <-- MtM --> projects <-- MtM --> users

User model

public function skills()
{
    return $this->belongsToMany('Skill')->withPivot('level');
}
public function projects(){

    return $this->belongsToMany('Project')->withPivot('user_id', 'project_id');
}

Skill model

public function users() {
    return $this->belongsToMany('User')->withPivot('level');
}
public function projects() {
    return $this->belongsToMany('Project')->withPivot('level');
}

Project model

public function users(){
    return $this->belongsToMany('User')->withPivot('user_id', 'project_id');
}
public function skills(){
    return $this->belongsToMany('Skill')->withPivot('level');
}

So, a Many to Many triangle. I want to get all the projects, the skills of which are subset of specific users skills. So basically "suggested projects" for user.

$projects = Project::whereHas('skills', function($q) use($array)
    {
        $q->thatAreSubsetOf($array);
        //$array contains names or ids of users skills
    })->orderBy('created_at', 'DESC')->get();

If some $user->skills are 'PHP', 'C' and 'Javascript', all the returned projects skills should only be subset of those (e.g. {'PHP', 'C'} or {'PHP', 'Javascript'} or {'Javascript', 'C'} or {'PHP', 'C', 'Javascript'} or {'PHP'}, or {'Javascript'} or {'C'}) I've tried many thing, researched a lot in Laravel Docs/here but can't seem to get what I want..

Basically your requirement can achieve Many To Many Polymorphic Relations. Your requirement is to use skills with User and Project, so its would be easy to handle with MTMPR.

Example below shows how I have implemented sharing Skill with both Project and User.

DB Schema

Skill

id              integer
name            string

skillable

id              integer
skillable_id    integer
skillable_type  string 

Models

Skill

class Skill extends Eloquent{
        public function projects(){
            return $this->morphedByMany('Project', 'skillable');
        }

        public function users(){
            return $this->morphedByMany('User', 'skillable');
        }
}

Project

class Project extends Eloquent{
        public function skills(){
            return $this->morphToMany('Skill', 'skillable');
        }
}

User

class User extends Eloquent{
    public function skills(){
        return $this->morphToMany('Skill', 'skillable');
    }
}

How to get skill from project

$project = Project::find($id);
$projectsSkill = $project->skills()->all();

And how you can get Project from skills

$skill = Skill::find(1);
$projects = $skill->projects();

If you still find something unclear to handle these situation, let me know.