ChatGPT Implements Work With Users Using the CQRS Pattern

There has been a lot of talk lately that AI will soon leave our brother without a job. Such speeches cannot but excite us, those who have completely devoted themselves and their lives to software development. Being very worried, I decided to check how this ChatGPT can replace me. Let's assume that I have no idea how to write code in symphony. And we will ask ChatGTP to teach us how to write a mini-project with user CRUD. And let's try to imagine that we don't know how to work with docker containers. And let him teach us all this. So, let's begin... Let's enter the following command in chatGPT: in ubuntu 20.04 you need to raise a new project on symphony in a docker container Let's do what we're told: Here's the first problem... we need the latest version of PHP. Let's tell AI about it: Change the instruction so that the latest version of php is indicated in the docker And here is the norm version of the docker file FROM php:latest-apache # Install additional dependencies if needed # RUN apt-get update && apt-get install -y ... # Enable Apache Rewrite module RUN a2enmod rewrite # Install Symfony CLI RUN curl -sS https://get.symfony.com/cli/installer | bash && \ mv /root/.symfony/bin/symfony /usr/local/bin/symfony # Install additional PHP extensions if needed # RUN docker-php-ext-install ... # Install Composer RUN curl -sS https://getcomposer.org/installer | php -- --install-dir=/usr/local/bin --filename=composer # Install PHP extensions for Symfony RUN docker-php-ext-install pdo pdo_mysql # Set the environment variable ENV APACHE_DOCUMENT_ROOT /var/www/html/public # Copy project files COPY . /var/www/html # Set file permissions for the project RUN chown -R www-data:www-data /var/www/html # Port to be exposed EXPOSE 80 Navigate to the directory where the Dockerfile is located, and execute the following command to build the Docker image. sudo docker build -t my-symfony-app . We get an error: ERROR: failed to solve: php:latest-apache: docker.io/library/php:latest-apache: not found I change in docker file to FROM php:latest-apache FROM php:8.1-apache Not working again. ERROR: failed to solve: process "/bin/sh -c curl -sS https://get.symfony.com/cli/installer | bash && mv /root/.symfony/bin/symfony /usr/local/bin/symfony" did not complete successfully: exit code: 1 Hmmm… Ok, with Docker I understand. I take the first docker file that comes across to work with Symphony from a Google search and voila ... everything works. Let's skip this failure, and try to implement a REST API for working with users. But let's complicate the task ... ask to do it with the CQRS (Command Query Responsibility Segregation) approach. Forming a request for AI: implement work with users on symphony with the CQRS approach At first, we received a general implementation without specifics. When working with users in Symfony using the CQRS (Command Query Responsibility Segregation) approach, you can follow these steps: Step 1: Define User Commands Create commands that represent the actions to be performed on users. These commands should encapsulate the intent and necessary data for creating, updating, and deleting users. For example, you can have commands like CreateUserCommand, UpdateUserCommand, and DeleteUserCommand. These commands should be part of your application's command namespace. Step 2: Implement User Command Handlers Create command handler classes responsible for handling the user commands. Each command handler should have a single responsibility and handle only one type of command. The command handlers will contain the business logic for executing the actions on users. For example, you can have CreateUserCommandHandler, UpdateUserCommandHandler, and DeleteUserCommandHandler classes. ... ... I showed only the first 2 steps, and I was given 21 of them in total. Our article would turn into a book))) Then we begin to ask it to write down each step in turn. Created a prompt: describe me step 1 1.1. Create a new directory within your Symfony project, such as . src/Application/User/Command 1.2. Inside the directory, create a new PHP class for each user command you want to define. For example, let's start with the . Command CreateUserCommand namespace App\Application\User\Command; class CreateUserCommand { private $username; private $email; private $password; public function __construct(string $username, string $email, string $password) { $this->username = $username; $this->email = $email; $this->password = $password; } public function getUsername(): string { return $this->username; } public function getEmail(): string { return $this->email; } public function getPassword(): string { return $this->password; } } Repeat the process to define other user commands, such as and , by creating separate PHP classes for each of them. Customize the properties and methods based on the data required for the specific action. UpdateUserCommand DeleteUserCommand If you don’t know how to do it, you can ask about it. show me realisation UpdateUserCommand or show me realisation DeleteUserCommand Having finished step 1, we move on to step 2. Step 2: Implement Command Handlers show me step 2 Create a new directory within your Symfony project, such as . src/Application/User/CommandHandler Inside the directory, create a new PHP class for each command handler. For example, let's start with the . CommandHandler CreateUserCommandHandler userRepository = $userRepository; } public function handle(CreateUserCommand $command): void { $username = $command->getUsername(); $email = $command->getEmail(); $password = $command->getPassword(); // Perform any necessary validation on the command data // Create a new User entity $user = new User($username, $email, $password); // Save the user to the repository $this->userRepository->save($user); } } Repeat the process to implement command handlers for other user commands, such as or . UpdateUserCommand DeleteUserCommand Each command handler class should have a method that accepts the respective command object and performs the required actions on the user entities. handle() If you don't know how to do it, ask the AI: show me realisation UpdateUserCommand and show me realisation DeleteUserCommand And move on to the next step. Step 3: Wire Up Command Handlers and Configure Command Bus Make sure you have the necessary packages installed for working with command buses and dependency injection in Symfony. You can install them using Composer: composer require symfony/messenger composer require symfony/dependency-injection Configure the Command Bus In your Symfony project, locate the file, and open it for editing. config/services.yaml Add the following configuration to enable the command bus and define its handler mappings: services: _defaults: autowire: true autoconfigure: true App\Application\User\CommandHandler\: resource: '../src/Application/User/CommandHandler' tags: ['messenger.message_handler'] App\Application\User\Command\: resource: '../src/Application/User/Command' Implement UserRepositoryInterface Create an interface for your user repository in the directory. This interface defines the methods for working with user entities, such as , , and . src/Domain/User findById() save() delete() Make sure your user repository class implements this interface. If you don't know how to do it, you know what to do ;)))) Then inject UserRepositoryInterface into Command Handlers Update your command handlers to inject an instance of into their constructors. This allows the handlers to access the user repository and perform the necessary operations on user entities. UserRepositoryInterface Then dispatch User Commands and have them handled by the command handlers; you can use the Symfony Messenger component. In your application code, when you want to execute a user command, dispatch it using the service. message_bus In your Symfony project, locate the file, and open it for editing. config/packages/messenger.yaml Ensure that the following configuration is present or add it if it's not already there: framework: messenger: buses: messenger.bus.commands: ~ This configuration defines a message bus named for handling commands. messenger.bus.commands In your Symfony project, locate the file, and make sure the following line is not commented out: config/bundles.php Symfony\Bundle\MessengerBundle\MessengerBundle::class => ['all' => true], This line ensures that the MessengerBundle is enabled. Next, we are offered the implementation of the controller use App\Application\User\Command\CreateUserCommand; use Symfony\Component\Messenger\MessageBusInterface; class UserController { private $commandBus; public function __construct(MessageBusInterface $commandBus) { $this->commandBus = $commandBus; } public function createUserAction(): Response { $command = new CreateUserCommand('john_doe', 'john@example.com', 'password123'); $this->commandBus->dispatch($command); // Handle the response or return a success message // ... } } And again, the problem. We do not see how we should receive and transfer client data to the command. Let's try to persuade him to help us. show me how I can get params from client request and put in this controller To retrieve parameters from a client request and pass them to a controller in Symfony, you can use the object and its methods. Here's an example of how you can do this: Request use Symfony\Component\HttpFoundation\Request; use Symfony\Component\HttpFoundation\Response; class UserController { public function createUserAction(Request $request): Response { $username = $request->request->get('username'); $email = $request->request->get('email'); $password = $request->request->get('password'); // Perform validation or other operations with the parameters // Create a CreateUserCommand using the parameters $command = new CreateUserCommand($username, $email, $password); // Dispatch the command to the command bus $this->commandBus->dispatch($command); // Handle the response or return a success message // ... return new Response('User created', 200); } } Adding the previous version to the current one, we get the following: commandBus = $commandBus; } public function createUserAction(Request $request): Response { $username = $request->request->get('username'); $email = $request->request->get('email'); $password = $request->request->get('password'); // Perform validation or other operations with the parameters // Create a CreateUserCommand using the parameters $command = new CreateUserCommand($username, $email, $password); // Dispatch the command to the command bus $this->commandBus->dispatch($command); // Handle the response or return a success message // ... return new Response('User created', 200); } } We go further… Create Query Classes In the query side of the CQRS pattern, you'll typically have query classes that represent the data you want to retrieve from the database or other data sources. These query classes encapsulate the data requirements for specific use cases. Create query classes that correspond to the data you need to fetch for your application. For example, you might have a to retrieve a user by their ID or a to fetch a list of users. GetUserByIdQuery GetUsersQuery namespace App\Application\User\Query; class GetUserByIdQuery { private $userId; public function __construct(string $userId) { $this->userId = $userId; } public function getUserId(): string { return $this->userId; } } You can create similar query classes based on your application's requirements. Create Query Handlers Query handlers are responsible for executing the queries and fetching the data from the appropriate data source. These handlers receive the query object, retrieve the requested data, and return the result. Create query handler classes that correspond to your query classes. For example, you might have a to handle the and fetch the user by their ID. GetUserByIdQueryHandler GetUserByIdQuery namespace App\Application\User\QueryHandler; use App\Application\User\Query\GetUserByIdQuery; use App\Domain\User\UserRepositoryInterface; class GetUserByIdQueryHandler { private $userRepository; public function __construct(UserRepositoryInterface $userRepository) { $this->userRepository = $userRepository; } public function __invoke(GetUserByIdQuery $query) { $userId = $query->getUserId(); // Retrieve the user from the repository $user = $this->userRepository->findById($userId); return $user; } } In this example, the class is responsible for handling the . The handler's method is invoked when the query is executed. GetUserByIdQueryHandler GetUserByIdQuery __invoke() Inside the method, you can extract the necessary information from the query object, such as the user ID. __invoke() Next, you can use the to retrieve the user from the repository by calling the method. UserRepositoryInterface findById() Finally, you can return the fetched user or the desired result based on your application's requirements. Create query handler classes for other query types in a similar fashion. Register Query Handlers To enable the dispatching and handling of queries, you need to register the query handlers in your Symfony application. In your Symfony project, locate the file and add the following configuration: config/services.yaml services: App\Application\User\QueryHandler\: resource: '../src/Application/User/QueryHandler' tags: ['messenger.message_handler'] This configuration maps the query handler classes within the directory to the tag, indicating that they should be considered message handlers. App\Application\User\QueryHandler messenger.message_handler With this configuration in place, Symfony's Messenger component will automatically discover and invoke the appropriate query handler based on the dispatched query. Dispatch Queries To dispatch queries and retrieve data, you can use the provided by Symfony's Messenger component. Here's an example of how you can do this: MessageBusInterface queryBus = $queryBus; } public function getUserAction(string $userId): Response { $query = new GetUserByIdQuery($userId); $user = $this->queryBus->dispatch($query)->getResult(); // Handle the user data or return a response // ... return new Response('User retrieved', 200); } } In this example, the method in the is responsible for handling a request to retrieve a user by their ID. getUserAction UserController The is injected through the constructor, allowing you to dispatch queries using the method. MessageBusInterface dispatch() You can create a object, passing the desired user ID as a parameter. GetUserByIdQuery Next, you can dispatch the query using the query bus, and retrieve the result using the method. getResult() You can then handle the user data or return a response based on your application's requirements. Hmmm… Again not completed ... and it is not clear what to do next. I dial in response - continue and… Update the Controller In the previous steps, we implemented separate methods for handling commands and queries in the controller. However, in many cases, you might need to handle both commands and queries within the same controller. Update your controller to handle both commands and queries by injecting both the for commands and the for queries. Here's an example: MessageBusInterface QueryBusInterface use App\Application\User\Command\CreateUserCommand; use App\Application\User\Query\GetUserByIdQuery; use Symfony\Component\HttpFoundation\Request; use Symfony\Component\HttpFoundation\Response; use Symfony\Component\Messenger\MessageBusInterface; use Symfony\Component\Messenger\Stamp\HandledStamp; use Symfony\Component\Routing\Annotation\Route; class UserController { private $commandBus; private $queryBus; public function __construct(MessageBusInterface $commandBus, MessageBusInterface $queryBus) { $this->commandBus = $commandBus; $this->queryBus = $queryBus; } /** * @Route("/users", methods={"POST"}) */ public function createUser(Request $request): Response { // Retrieve data from the request $username = $request->request->get('username'); $email = $request->request->get('email'); $password = $request->request->get('password'); // Create the command and dispatch it $command = new CreateUserCommand($username, $email, $password); $this->commandBus->dispatch($command); // Handle the response or return a success message // ... return new Response('User created', 200); } /** * @Route("/users/{id}", methods={"GET"}) */ public function getUser(string $id): Response { // Create the query and dispatch it $query = new GetUserByIdQuery($id); $envelope = $this->queryBus->dispatch($query); // Retrieve the result from the handled envelope /** @var HandledStamp $handledStamp */ $handledStamp = $envelope->last(HandledStamp::class); $user = $handledStamp->getResult(); // Handle the user data or return a response // ... return new Response('User retrieved', 200); } } And again, we didn't get the full implementation. We do not have a response with user data. show me getUser with realisation of Handle the user data or return a response <?php namespace App\Controller\User; use App\Application\User\Query\GetUserByIdQuery; use Symfony\Component\HttpFoundation\Response; use Symfony\Component\Messenger\MessageBusInterface; use Symfony\Component\Messenger\Stamp\HandledStamp; use Symfony\Component\Routing\Annotation\Route; class GetUserController { private $queryBus; public function __construct(MessageBusInterface $queryBus) { $this->queryBus = $queryBus; } /** * @Route("/users/{id}", methods={"GET"}) */ public function getUser(string $id): Response { // Create the query and dispatch it $query = new GetUserByIdQuery($id); $envelope = $this->queryBus->dispatch($query); // Retrieve the result from the handled envelope $result = $envelope->last(HandledStamp::class)->getResult(); if ($result === null) { // User not found, return a 404 Not Found response return new Response('User not found', 404); } // User found, handle the user data $user = [ 'id' => $result->getId(), 'username' => $result->getUsername(), 'email' => $result->getEmail(), ]; // Return a JSON response with the user data return new Response(json_encode($user), 200, ['Content-Type' => 'application/json']); } } Configure Messenger Component In Symfony, the Messenger component is used to handle messages, including commands and queries. To use the component, you need to configure it in your Symfony application. Open the file in your Symfony project, and add the following configuration: config/packages/messenger.yaml framework: messenger: default_bus: command.bus buses: command.bus: middleware: - messenger.middleware.validation - messenger.middleware.handle_message query.bus: middleware: - messenger.middleware.handle_message In this configuration, we define two buses: and . The is set to , indicating that it will be the default bus used for commands. command.bus query.bus default_bus command.bus We configure the middleware for each bus. For the , we include the middleware, which enables message validation, and the middleware, which handles the messages by invoking the appropriate handlers. command.bus messenger.middleware.validation messenger.middleware.handle_message For the , we only include the middleware, as validation is typically not necessary for queries. query.bus messenger.middleware.handle_message You can customize the configuration based on your specific needs. Register Command and Query Handlers To enable the handling of commands and queries, you need to register the corresponding command handlers and query handlers in your Symfony application. In your Symfony project, locate the file and add the following configuration: config/services.yaml services: App\Application\User\CommandHandler\: resource: '../src/Application/User/CommandHandler' tags: ['messenger.message_handler'] App\Application\User\QueryHandler\: resource: '../src/Application/User/QueryHandler' tags: ['messenger.message_handler'] This configuration maps the command handler classes within the directory and the query handler classes within the directory to the tag, indicating that they should be considered message handlers. App\Application\User\CommandHandler App\Application\User\QueryHandler messenger.message_handler With this configuration in place, Symfony's Messenger component will automatically discover and invoke the appropriate command and query handlers based on the dispatched messages. Ensure that the command handlers and query handlers are correctly placed in the respective directories and have the necessary dependencies injected. Inject the Buses Finally, you need to inject the command bus and query bus into the controllers or services where you want to use them. With the buses injected, you can now use them to dispatch commands and queries within the controller or service. Remember to import the necessary classes and ensure that the buses and related dependencies are correctly wired and configured. Let's continue. Update the UserRepositoryInterface The UserRepositoryInterface defines the contract for interacting with the user data storage, such as a database or any other persistence mechanism. Update the interface to include the necessary methods for creating, updating, deleting, and retrieving user entities. use App\Domain\User\User; interface UserRepositoryInterface { public function save(User $user): void; public function update(User $user): void; public function delete(User $user): void; public function findById(string $id): ?User; public function findByEmail(string $email): ?User; // Additional methods for retrieving users based on specific criteria } Implement the UserRepository Next, you need to implement the UserRepositoryInterface in a concrete UserRepository class that interacts with your chosen data storage. use App\Domain\User\User; use Doctrine\ORM\EntityManagerInterface; class UserRepository implements UserRepositoryInterface { private $entityManager; public function __construct(EntityManagerInterface $entityManager) { $this->entityManager = $entityManager; } public function save(User $user): void { $this->entityManager->persist($user); $this->entityManager->flush(); } public function update(User $user): void { $this->entityManager->flush(); } public function delete(User $user): void { $this->entityManager->remove($user); $this->entityManager->flush(); } public function findById(string $id): ?User { return $this->entityManager->getRepository(User::class)->find($id); } public function findByEmail(string $email): ?User { return $this->entityManager->getRepository(User::class)->findOneBy(['email' => $email]); } } Again, the question is... where should we place our repository? ChatGPT answer: The UserRepository needs to be created as part of the implementation of the infrastructure layer in your Symfony application. The infrastructure layer is responsible for interacting with external systems and resources, such as databases, APIs, or file systems. Typically, the UserRepository is created within the infrastructure folder or namespace of your Symfony project's directory structure. Here's a common approach: Create a new folder called within the directory of your Symfony project. Infrastructure src Inside the folder, create a subfolder called , or any appropriate name that reflects the domain or module you're working with. Infrastructure User Within the folder, create a new file called to contain the UserRepository implementation. User UserRepository.php Place the UserRepository implementation in the file within the appropriate namespace, such as . UserRepository.php App\Infrastructure\User Remember to update the namespace and import the necessary classes in the UserRepository file. Additionally, make sure you configure the dependency injection container in Symfony to properly instantiate and inject the UserRepository. This typically involves creating a service definition for the UserRepository in your Symfony project's service configuration file (e.g., or a specific configuration file). services.yaml UserBundle Here's an example of how the UserRepository service definition might look like in the file: services.yaml services: App\Infrastructure\User\UserRepository: arguments: - '@doctrine.orm.entity_manager' # Other configuration options for the UserRepository service In this example, the UserRepository service is defined, and the service is injected as an argument. doctrine.orm.entity_manager Remember to adjust the service definition according to your actual implementation and requirements. And again the question ... but no one told us that we need to install packages to work with the doctrine… Install Doctrine: Use Composer, the dependency management tool for PHP, to install the necessary Doctrine packages. The most commonly used packages are and . doctrine/orm doctrine/doctrine-bundle Let's continue, which involves configuring the Symfony Messenger component to handle the commands and queries. Configure Symfony Messenger Open the file, and update it with the following configuration: config/packages/messenger.yaml framework: messenger: transports: async: '%env(MESSENGER_TRANSPORT_DSN)%' routing: 'App\Application\User\Command\CreateUserCommand': async 'App\Application\User\Command\UpdateUserCommand': async 'App\Application\User\Command\DeleteUserCommand': async 'App\Application\User\Query\GetUserQuery': async In this example, we configure the Symfony Messenger component with a single transport named "async" using the environment variable. We define the routing for each command and query class, specifying that they should be handled by the "async" transport. MESSENGER_TRANSPORT_DSN Update services.yaml Open the file, and update it with the following services: config/services.yaml services: App\Application\User\Command\UserCommandHandler: public: true autowire: true App\Application\User\Query\UserQueryHandler: public: true autowire: true App\Domain\User\UserRepositoryInterface: alias: App\Infrastructure\Persistence\DoctrineUserRepository In this example, we define the services for the , , and the . UserCommandHandler UserQueryHandler UserRepositoryInterface Make sure to adjust the service definitions based on your application's requirements. That's it! You have configured the Symfony Messenger component to handle the commands and queries. Next, we get a lot of advice on how to improve the code, plus how to check the work of our code with data validation and filtering. But got nothing about entity creation and data mapping. Let's ask him to explain where and at what step he should have told us about it. At what step did you have to tell us about the creation of the User entity and the mapping of its data I apologize for the oversight. It seems I missed explaining the steps related to creating the User entity and mapping its data. I apologize for any confusion caused. To provide you with the complete picture, here are the additional steps for creating the User entity and mapping its data using Doctrine: Step 7: Create the User Entity 7.1. Create a new directory called inside the directory. Entity src/Domain/User 7.2. Inside the directory, create a new file called with the following content: Entity User.php <?php namespace App\Domain\User\Entity; use Doctrine\ORM\Mapping as ORM; /** * @ORM\Entity * @ORM\Table(name="users") */ class User { /** * @ORM\Id * @ORM\GeneratedValue * @ORM\Column(type="integer") */ private $id; /** * @ORM\Column(type="string", length=255) */ private $username; /** * @ORM\Column(type="string", length=255) */ private $email; /** * @ORM\Column(type="string", length=255) */ private $password; // Getters and Setters public function getId(): ?int { return $this->id; } public function getUsername(): ?string { return $this->username; } public function setUsername(string $username): void { $this->username = $username; } public function getEmail(): ?string { return $this->email; } public function setEmail(string $email): void { $this->email = $email; } public function getPassword(): ?string { return $this->password; } public function setPassword(string $password): void { $this->password = $password; } } This code defines the User entity class with its properties and their corresponding annotations for Doctrine ORM mapping. Step 8: Update Doctrine Configuration 8.1. Open the file. config/packages/doctrine.yaml 8.2. Ensure that the section is properly configured with your database credentials. dbal 8.3. Ensure that the section has the following configuration: orm orm: auto_generate_proxy_classes: true naming_strategy: doctrine.orm.naming_strategy.underscore auto_mapping: true mappings: App: is_bundle: false type: annotation dir: '%kernel.project_dir%/src/Domain' prefix: 'App\Domain' alias: App This configuration tells Doctrine to look for entity mappings in the directory. src/Domain Step 9: Generate the Database Schema 9.1. Run the following command to generate the database schema based on the entity mapping: $ php bin/console doctrine:schema:create This command will create the necessary tables in your database based on the entity mappings. With these additional steps, you have created the User entity and mapped its data using Doctrine. So we got something working ... And we see that without a person it cannot be working yet ... We need to understand what ChatGPT offers us and correct it often. But I see him as a super helper for us. If you like this approach, let me know, and in the next few articles, I will show how we can improve this functionality using chatGPT, adding full parameter validation and correctly handling exceptions. You can also try to use it to write authorization through third-party services.