Command

Description

Command is behavioral design pattern that converts requests or simple operations into objects.

• Chuyển request thành object

Example

Xử lí lưu post với các trạng thái yêu cầu là draft, no approval, pusblish,..

1. Class xử lí business logic cho post:

   class PostReceiver
   {
   	public function draft() 
   	{
   		// do something
   	}
       
       public function noApproval() 
   	{
   		// do something
   	}
       
       public function publish() 
   	{
   		// do something
   	}
   }

2. Command:

   interface Command
   {
   	public function excute();
   }

3. Concreate command: class implement command define thực thi của Receiver tương ứng với case request.

   class DraftCommand implements Command
   {
       protected PostReceiver $receiver;
   
       public function __construct(PostReceiver $receiver)
       {
           $this->receiver = $receiver;
       }
   
       public function execute()
       {
           $this->receiver->saveDraft();
       }
   }

   class NoApprovalCommand implements Command
   {
       protected PostReceiver $receiver;
   
       public function __construct(PostReceiver $receiver)
       {
           $this->receiver = $receiver;
       }
   
       public function execute()
       {
           $this->receiver->saveNoApproval();
       }
   }

   class PublishCommand implements Command
   {
       protected PostReceiver $receiver;
   
       public function __construct(PostReceiver $receiver)
       {
           $this->receiver = $receiver;
       }
   
       public function execute()
       {
           $this->receiver->savePublish();
       }
   }

4. Invoker: Liên kết với command, gửi request đến command.

   class Invoker
   {
       private Command $command;
   
       public function setCommand(Command $cmd)
       {
           $this->command = $cmd;
       }
   
       public function run()
       {
           $this->command->execute();
       }
   }

5. Usage:

   $invoker = new Invoker();
   $postReceiver = new PostReceiver();
   
   $invoker->setCommand(new DraftCommand($postReceiver));
   $invoker->run();

→ Dễ dàng thêm các command mới mà vẫn tuân thủ Open/Closed Principle .
→ Dễ thực hiện unit testing.