How to Order Related Models in Laravel Using `orderBy`?

Ordering Relationships in Laravel

When retrieving a set of related models, it's often useful to order them in a specific way. In Laravel, this can be achieved using the orderBy method.

Ordering HasMany Relationships

Consider the following scenario where you're looping through all comments posted by the Author of a particular post:

foreach($post->user->comments as $comment) {
    echo "<li>" . $comment->title . " (" . $comment->post->id . ")</li>";
}

This code will display the following list of comments:

I love this post (3)
This is a comment (5)
This is the second Comment (3)

To order the comments by post ID, extend the hasMany relationship in the User model:

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

Replace column with the name of the column you want to order by. In this case, we'll use id:

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

This will update the order of the comments to be:

I love this post (3)
This is the second Comment (3)
This is a comment (5)

Ordering with Query Parameters

In addition to hard-coding the order in the relationship, you can also order based on a query parameter. To do this, define a route in your routes.php file:

Route::get('users/{user}/comments', 'UserController@index');

And then create a corresponding index method in your UserController:

public function index($user)
{
    $column = Input::get('orderBy', 'defaultColumn');
    $comments = $user->comments()->orderBy($column)->get();

    // ...
}

When you visit the route with a orderBy parameter, the comments will be ordered accordingly. For example, visiting the following URL would order the comments by the created_at column:

http://localhost/users/1/comments?orderBy=created_at

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