Laravel Collection Key Method

In this tutorial we will see laravel collection key method.

Laravel collection key method

The `key` method in Laravel collection returns the key of the first item in the collection that passes a given truth test. If no item passes the test, the method returns null.

The syntax of the `key` method is:

$collection->key($callback);

Here, `$collection` is the instance of the Laravel collection, and `$callback` is an optional closure or string used to test each item in the collection. If `$callback` is not provided, the `key` method returns the key of the first item in the collection.

Example Usage:

Let's say we have a collection of students, and we want to find the key of the first student whose name starts with the letter 'J'. We can use the `key` method as follows:

$students = collect([
    ['name' => 'John', 'age' => 21],
    ['name' => 'Jane', 'age' => 22],
    ['name' => 'Jim', 'age' => 23],
    ['name' => 'Jake', 'age' => 24],
]);

$key = $students->key(function ($student, $key) {
    return substr($student['name'], 0, 1) === 'J';
});

echo $key; // Output: 0

In the above example, the `key` method returns the key 0, which is the index of the first student in the collection whose name starts with the letter 'J' (i.e., 'John').