Laravel 5.8检索关注者信息

Question

I have a follow users system in place for my application written in Laravel and I am trying to retrieve data from my DB based on certain followers. It's a recipe application with a users, recipes, and followers table. I am currently retrieving a users followers by writing $user->followers. However, I want to set up my relationship in such a way so that I can retrieve the particular recipes that belong to a given users followers. Something along the lines of $user->followers->recipes. I don't have the correct logic or Eloquent relationships in place to do that right now. Any suggestions on how that might get done?

User Model

public function followers(){
        return $this->belongsToMany(User::class, 'followers', 'leader_id', 'follower_id')->withTimestamps();
    }

    public function followings(){
        return $this->belongsToMany(User::class, 'followers', 'follower_id', 'leader_id')->withTimestamps();
    }

Recipe Model

public function user(){
        return $this->belongsTo('App\User');
    }

    public function category(){
        return $this->belongsTo('App\Category');
    }

    public function comments(){
        return $this->hasMany('App\Comment'); 
    }

    public function likes(){
        return $this->hasMany('App\Like');
    }

FollowerController

class FollowerController extends Controller
{
    public function followUser($id){
        $user = User::find($id);

        if(!$user){
            return redirect()->back()->with('error', 'User does not exist.');
        }

        $user->followers()->attach(auth()->user()->id);

        return redirect()->back()->with('success', 'You now follow the user!');
    }

    public function unfollowUser($id){
        $user = User::find($id);

        if(!$user){
            return redirect()->back()->with('error', 'User does not exist.');
        }

        $user->followers()->detach(auth()->user()->id);
        return redirect()->back()->with('success', 'You unfollowed the user!');
    }

    public function show($id){
        $user = User::find($id);
        $followers = $user->followers;
        $followings = $user->followings;

        return view('welcome')->with('user', $user);
    }

Is there any way I can setup a relationship between models User, Recipe, and Follow? What would be the best way to go about retrieving any information pertaining to the particular set of followers of a user? Let me know if I need to share anymore code with you guys! Thanks for the help!

Answer 1

What you need is a HasManyThrough relationship.

In your User model:

public function recipes()
{
    return $this->hasManyThrough(
        'App\Recipe',
        'App\User',
        'leader_id',
        'user_id',
        'id',
        'id'
    );
}

Complete documentation (you may need to better set some foreign keys) can be found at: https://laravel.com/docs/5.8/eloquent-relationships#has-many-through .

EDIT: I'm wrong. Your followers relationship is a many-to-many, not a one-to-many, so this method is not gonna work. I will leave here the comment in case someone has trouble with a one-to-many relation.

Answer 2

You can define a direct relationship by "skipping" the users table:

class User extends Model
{
    public function followerRecipes() {
        return $this->belongsToMany(
            Recipe::class, 'followers', 'leader_id', 'follower_id', null, 'user_id'
        );
    }
}