Laravel eager loading nested relationship

php
$books = App\Book::with('author.contacts')->get();

You can also specify which columns to include for each relationship:

php
$books = App\Book::with('author:id,name', 'author.contacts:id,phone')->get();

This will only load the `id` and `name` columns from the `authors` table, and the `id` and `phone` columns from the `contacts` table.

To add constraints to the eager loading query, you can pass a closure to the `with` method:

php
$users = App\User::with(['posts' => function ($query) {
    $query->where('title', 'like', '%first%');
}])->get();

This will only eager load posts where the `title` column contains the word "first".

If you need to eager load a relationship after the parent model has already been retrieved, you can use the `load` method:

php
$books = App\Book::all();
if ($someCondition) {
    $books->load('author', 'publisher');
}

You can also add constraints to the `load` method:

php
$books->load(['author' => function ($query) {
    $query->orderBy('published_date', 'asc');
}]);

Remember to always include the foreign key columns when eager loading nested relationships, or the nested models may not load at all[4].