Using Gate auth to check if a user is a moderator - getting Missing argument 3 for Illuminate\Auth\AuthServiceProvider

Check what the value of your variables are as it appears that it is missing the third argument, namely $subreddit.

Also, what happens when you remove the [] around the $post->id?

@can('update-post', $post, $subreddit)
        <a href="{{ action('PostsController@edit', $post->id) }}">Edit</a>
    @endcan

@mstnorris I think the problem was I need to pass $post and $subreddit in an array like so [$post, $subreddit]

Now I'm getting a different error

ErrorException in AuthServiceProvider.php line 29:

Trying to get property of non-object (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php) (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php)

It's referring to $subreddit->moderator->user_id but how else can I access the moderator's user_id?

Are you importing Gate properly at the top?

use Gate;

Have you set up the relevant relationship on the Subreddit and Moderator models? If you have, then that Subreddit doesn't have a Moderator.

Try:

$subreddit->moderator()->user_id

Here are my relations for Subreddit

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

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

    public function moderators() {
        return $this->belongsToMany('App\User','moderators');
    }

And Moderator

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

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

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

I'm positive that at least 1 moderator exists for that subreddit, the record is in the db.

@mstnorris Yes I am using Gate at the top. and using $subreddit->moderators()->user_id gives

Undefined property: Illuminate\Database\Eloquent\Relations\BelongsToMany::$user_id (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php) (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php)

moderators() with s

You don't have a moderator relationship on you Subreddit model. That's why you're having trouble as you're calling it like a one-to-many relationship, yet you've set up a many-to-many.

@mstnorris so how should it be? one-to-one or many-to-many?

That depends on what you need.

Explain what the use case is between a subreddit and moderators? Does asubreddit have one or many moderators?

@mstnorris

Subreddits have many moderators, and many posts.

Here I am simply checking if the logged in user_id is the same as user_id of moderators table related to the subreddit the post belongs to.

@ufodisko Before we go any further, you're relationships aren't right. Take a look at them and the documentation to help you out. Before we continue, this is undoubtedly causing issues.

hasOne <=> belongsTo

hasMany <=> belongsTo

belongsToMany <=> belongsToMany

@mstnorris can you be more specific as to where I got the relationships wrong? Because everything else works. I've read the documentation and followed the instructions.

Here are all 3 models and their relations.

Subreddit Model

class Subreddit extends Model
{
    protected $fillable = [
        'name',
        'description'
    ];

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

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

    public function moderators() {
        return $this->hasMany('App\User', 'moderators');
    }
}

Post Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Post extends Model
{
    protected $fillable = [
        'title',
        'link',
        'text',
        'image',
        'subreddit_id'
    ];

    // this was preventing the Votes relation from working..
    //    protected $primaryKey = 'subreddit_id';

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

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

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

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

Moderator Model

<?php

namespace App;

use Illuminate\Database\Eloquent\Model;

class Moderator extends Model
{
    protected $table = 'moderators';

    protected $fillable = ['user_id', 'subreddit_id'];

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

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

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

Can a Moderator, moderate more than one Subreddit?

@mstnorris yes, he can.

And a post belongs to only one subreddit and has many moderators as well.

In that case you need a Many-to-Many relationship between Subreddits and Moderators.

Subreddit Model

public function moderators() {
    return $this->belongsToMany('App\Moderator');
}

Moderator Model

public function subreddits() {
    return $this->belongsToMany('App\Subreddit');
}

Also, please show your migrations too as that will be affected by the change in relationships. As mentioned above you'll need to create a moderator_subreddit pivot table.

@mstnorris still getting the same error

Undefined property: Illuminate\Database\Eloquent\Relations\BelongsToMany::$user_id (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php) (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php)

Please note that I am also linking App\User in the Subreddit Model

public function moderators() {
        return $this->belongsToMany('App\User', 'moderators');
}

@ufodisko I suggest that you think about how your models relate to one another. If it helps, use http://laravelsd.com as you'll be able to visualise it clearly. You can also export your database migrations too.

Going back to your original question, were you ever passing three arguments?

@mstnorris What do you mean by was I ever passing 3 arguments? I don't understand the question.

I just tried something, changed the relation on Subreddit Model to belongsTo

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

I am getting a different error now

Undefined property: App\Subreddit::$moderators (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php) (View: C:\xampp\htdocs\reddit\resources\views\partials\post.blade.php)

Let me see your migrations.

@mstnorris here you can check all the files of the app https://github.com/Halnex/laravel-reddit

@ufodisko I've cloned it, set up the database (I can't seed it as you don't have a PermissionsTableSeeder), what should I see.

Please explain your app to me and I'll try my best to help.

@mstnorris First you need to open AuthServiceProvider and add the following method.

public function boot(GateContract $gate)
    {
        parent::registerPolicies($gate);

        $gate->define('update-post', function ($user, $post, $subreddit) {
            // Check if user is subreddit owner
            if ($user->id === $post->subreddit->user->id) {
                return true;
            }

            // Check if user is the post author
            if ($user->id === $post->user_id) {
                return true;
            }

            if ($user->id === $subreddit->moderators->user_id) {
                return true;
            }

            return false;
        });

        $gate->define('update-sub', function($user, $subreddit) {
            if($user->id === $subreddit->user->id) {
                return true;
            }

            return false;
        });
    }

After that you need to

• Register for an account
• Create New Subreddit (create sub link)
• Create New Post (create post link)
• Assign A mod to your sub (My subreddit link in the user menu)

And that's it, you don't need to seed. But I think you'll get an error once you run it due to the issue we're trying to solve.

@mstnorris Oh and be sure to change the ajax requests url to relative urls on the views. I forgot to change them before committing.

The project isn't loading for me, not even the homepage.

It's late here. I'll take a look in the morning.

Alright, no worries

You were just required to add the $user model. @can('update-post', $user, $post, $subreddit) @edit', [$post->id]) }}">Edit @endcan