Check for Exactly One Collection Item with containsOneItem()

Use containsOneItem() on Laravel Collections instead of count() === 1 to write cleaner, more expressive dataset assertions.

Checking whether a collection or filtered list contains exactly a single item (such as checking if a user has only one registered payment method or verifying single-item cart status) traditionally required $collection->count() === 1.

Laravel provides the expressive containsOneItem() method.

Basic Usage

$cart = collect([
    ['id' => 1, 'name' => 'Book', 'price' => 20]
]);

// Clear and readable
if ($cart->containsOneItem()) {
    $item = $cart->first();
    // Apply single-item shipping rate
}

In Authorization or Business Logic

// Prevent deleting the only remaining administrator account
if ($team->admins->containsOneItem()) {
    abort(422, 'Cannot remove the last remaining administrator.');
}

Summary

• Returns true only if the collection contains exactly 1 item; returns false if empty or containing multiple items.
• More expressive than checking count equality.
• Available on all Laravel Collection and LazyCollection instances.