How to get foreign key from eloquent collection in laravel

All we need is an easy explanation of the problem, so here it is.

I have hasMany relationship in my User model;

 /**
 * Get the posts for the users.
 */
public function posts()
{
    return $this->hasMany(Posts::class); //foreign key assigned by user_id
}

I need to get a foreign id in Eloquent data

Controller;

use App\Models\User;

$posts = User::find(1)->posts;

foreach ($posts as $post) {
    //
}
//for example
$foreign_key = $posts->foreign_key;
echo "all posts collection assigned foreign key is; ".$foreign_key;

Expected output;

1

How can I get the foreign key?

How to solve :

I know you bored from this bug, So we are here to help you! Take a deep breath and look at the explanation of your problem. We have many solutions to this problem, But we recommend you to use the first method because it is tested & true method that will 100% work for you.

Method 1

You can do the following. Since posts has hasmany relation so it return collection of object even though you have one item in posts.

foreach ($posts as $post) {
     
    echo $post->user_id;
}

or

 dd($posts->first()->user_id);

If you still need one item from posts relationship then you can add one relationship

public function post()
{
    return $this->hasOne(Posts::class); //foreign key assigned by user_id
}

then you can access

$posts = User::find(1)->post;

$foreign_key =$posts->user_id;

Note: Use and implement method 1 because this method fully tested our system.
Thank you 🙂

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