How to create a laravel relationship model with a SQL query like this

Question

I have query like this

SELECT * FROM 'discussions' INNER JOIN comments ON comments.commentable_id = discussions.id WHERE discussions.user_id = 1 ORDER BY comments.id DESC

How to create relationships in laravel models

Not with query builder like this

DB::table('discussions')
    ->join('comments', 'comments.commentable_id', '=', 'discussions.id')
    ->where('discussions.user_id', '=', 1)
    ->orderBy('comments.id', 'DESC')
    ->get();```

Answer 1

First you need to know what type of relationship it is.

One:One, One:Many, Many:Many, Many:One

After that you can take a look at the documentation

You create 2 models by calling to php artisan make:model <name> within your terminal, or by manually creating them.

After that you just do whatever documentation tells you to do.

Say you have one-to-many where one discussion has many comments, it is important you specify the foreign_key in the 2nd parameter if it's non-conventional naming.

namespace App\Models;

use Illuminate\Database\Eloquent\Model;

class Discussion extends Model
{
    /**
     * Get the comments for the discussions post.
     */
    public function comments()
    {
        // Watch the foreign_key in this instance 'commentable_id'
        return $this->hasMany(Comment::class, 'commentable_id');
    }
}

After that you can call something like

$comments = Discussion::where('user_id', 1)->first()->comments

To get all comments belonging to that discussion

I don't want to be a jerk, but the documentation is truly a wonderful source of information. And I advice you to read everything before starting your development journey.