tap() intersect() and diff() collection method

[techmahedy]

diff() example

Get items that exist in the first collection but not in the second

// Find users who haven't made purchases
$allUsers = User::all();
$purchasers = Order::all()->pluck('user_id')->unique();
$nonPurchasers = $allUsers->pluck('id')->diff($purchasers);

// Find removed features
$oldFeatures = new Collection(Model::class, ['feature1', 'feature2', 'feature3']);
$newFeatures = new Collection(Model::class, ['feature2', 'feature4']);
$removedFeatures = $oldFeatures->diff($newFeatures); // ['feature1', 'feature3']

intersect() example

Get items that exist in both collections

// Find users in both groups
$premiumUsers = User::where('premium', true)->get()->pluck('id');
$activeUsers = User::where('last_login > ?', $date)->get()->pluck('id');
$premiumActiveUsers = $premiumUsers->intersect($activeUsers);

// Find common interests
$user1Interests = new Collection(Model::class, ['sports', 'music', 'art']);
$user2Interests = new Collection(Model::class, ['music', 'coding', 'art']);
$commonInterests = $user1Interests->intersect($user2Interests); // ['music', 'art']

tap() example

Execute a callback without modifying the collection

// Debug pipeline
$result = $users
    ->filter(fn($u) => $u['active'])
    ->tap(fn($col) => Log::info("Active users: " . $col->count()))
    ->map(fn($u) => $u['email'])
    ->tap(fn($col) => Cache::set('active_emails', $col->all()))
    ->all();

// Send notification without breaking the chain
$orders = Order::pending()
    ->tap(fn($orders) => "Send notification")
    ->update(['status' => 'processing']);