static and non static methods in mvc websites

Question

currently i have a problem which don't allow me to continue adding features to my mvc website without do any sort of spaghetti code.

i have two classes, one is ModModel and the other is ModUploadModel. both are extended with the Model class. ModModel contains all the methods about "mods", as ModModel->doesModNameExists(), ModModel->getModDetails() etc... ModUploadModel contains all the methods for the uploading of a mod, as ModUploadModel->upload(), ModUploadModel->isModNameValid() etc...

in some cases i have to call some ModModel methods from ModUploadModel, and to do so i have to create a new instance of ModModel inside the ModUploadController and to pass it as an argument to ModUploadModel->upload(). for example: the ModUploadController creates two new objects, $modModel = new ModModel() and $modUploadModel = new ModUploadModel(), then calls $modUploadModel->upload($modModel).

this is the ModUploadController, which creates the two objects and call the ModUploadModel->upload() method

class ModUploadController extends Mvc\Controller {

    public function uploadMod(): void {
        $modUploadModel = new ModUploadModel()
        $modModel = new ModModel();

        // $modModel needs to be passed because the ModUploadModel needs
        // one of its methods
        if ($modUploadModel->upload("beatiful-mod", $modModel)) {
            // success
        } else {
            // failure
        }
    }
}

ModUploadModel->upload() checks if the input is valid (if the mod name isn't already taken etc), and finally upload the mod data into the db. obviously it's all suddivise in more sub private methods, as ModUploadModel->isModNameValid() and ModUploadModel->insertIntoDb().

the problem is that i don't structured my classes with all static methods, and everytime i have to pass objects as parameters, like with ModModel (for example i need its isModNameValid() method). i thought about making all the ModModel methods static, but that's not as simple as it seems, because all its methods query the db, and they use the Model->executeStmt() method (remember that all the FooBarModel classes are extended with the Model class, which contains usefull common methods as executeStmt() and others), and calling a non static method from a static one is not a good practice in php, so i should make static the Model methods too, and consequently also the Dbh methods for the db connection (Model is extended with Dbh).

the ModModel class:

class ModModel extends Mvc\Model {

    // in reality it queries the db with $this->executeStmt(),
    // which is a Model method
    public function doesModNameExists($name) {
        if (/* exists */) {
            return true;
        }

        return false;
    }

}

the ModUploadModel class:

class ModUploadModel extends Mvc\Model {

    private $modName;

    public function upload($modName, $modModel) {
        $this->modName = $modName;

        if (!$this->isModNameValid($modModel)) {
            return false;
        }
    
        if ($this->insertIntoDb()) {
            return true;
        }
    
        return false;
    }
    
    // this methods needs to use the non static doesModNameExists() method
    // which is owned by the ModModel class, so i need to pass
    // the object as an argument
    private function isModNameValid($modModel) {
        if ($modModel->doesModNameExists($this->modName)) {
            return false;
        }
        
        // other if statements

        return true;
    }
    
    private function insertIntoDb() {
        $sql = "INSERT INTO blabla (x, y) VALUES (?, ?)";
        $params = [$this->modName, "xxx"];
    
        if ($this->executeStmt($sql, $params)) {
            return true;
        }
    
        return false;
    }
}

the alternative would be to create a new instance of Model inside the ModModel methods, for example (new Model)->executeStmt(). the problem is that it's not a model job to create new objects and generally it's not the solution i like most.

Answer 1

Some observations and suggestions:

[a] You are passing a ModModel object to ModUploadModel to validate the mod name before uploading. You shouldn't even try to call ModUploadModel::upload() if a mod with the provided name already exists. So you should follow steps similar to this:

class ModUploadController extends Mvc\Controller {

    public function uploadMod(): void {
        $modUploadModel = new ModUploadModel()
        $modModel = new ModModel();

        $modName = 'beatiful-mod';

        try {
            if  ($modModel->doesModNameExists($modName)) {
                throw new \ModNameExistsException('A mod with the name "' . $modName . '" already exists');
            }

            $modUploadModel->upload($modName);
        } catch (\ModNameExistsException $exception){
            // ...Present the exception message to the user. Use $exception->getMessage() to get it...
        }
    }
}

[b] Creating objects inside a class is a bad idea (like in ModUploadController ). Use dependency injection instead. Read this and watch this and this . So the solution would look something like this:

class ModUploadController extends Mvc\Controller {

    public function uploadMod(ModUploadModel $modUploadModel, ModModel $modModel): void {
        //... Use the injected objects ($modUploadModel and $modModel ) ...
    }
}

In a project, all objects that need to be injected into others can be created by a "dependency injection container" . For example, PHP-DI (which I recommend), or other DI containers . So, a DI container takes care of all dependency injections of your project. For example, in your case, the two objects injected into ModUploadController::uploadMod method would be automatically created by PHP-DI. You'd just have to write three lines of codes in the file used as the entry-point of your app, probably index.php :

use DI\ContainerBuilder;

$containerBuilder = new ContainerBuilder();
$containerBuilder->useAutowiring(true);
$container = $containerBuilder->build();

Of course, a DI container requires configuration steps as well. But, in a couple of hours, you can understand how and where to do it.

By using a DI container, you'll be able to concentrate yourself solely on the logic of your project, not on how and where various components should be created, or similar tasks.

[c] Using static methods is a bad idea. My advise would be to get rid of all static methods that you already wrote. Watch this , read this , this and this . So the solution to the injection problem(s) that you have is the one above: the DI, perfomed by a DI container. Not at all creating static methods.

[d] You are using both components to query the database ( ModModel with doesModNameExists() and ModUploadModel with insertIntoDb() ). You should dedicate only one component to deal with the database.

[e] You don't need Mvc\Model at all.

[f] You don't need Mvc\Controller at all.

Some code:

I wrote some code, as an alternative to yours (from which I somehow "deduced" the tasks). Maybe it will help you, seeing how someone else would code. It would give you the possibility of "adding features to my mvc website without do any sort of spaghetti code" . The code is very similar to the one from an answer that I wrote a short time ago. That answer also contains additional important suggestions and resources.

Important : Note that the application services, eg all components from Mvc/App/Service/ , should communicate ONLY with the domain model components, eg with the components from Mvc/Domain/Model/ (mostly interfaces), not from Mvc/Domain/Infrastructure/ . In turn, the DI container of your choice will take care of injecting the proper class implementations from Mvc/Domain/Infrastructure/ for the interfaces of Mvc/Domain/Model/ used by the application services.

Note: my code uses PHP 8.0. Good luck.

Project structure:

Mvc/App/Controller/Mod/AddMod.php:

<?php

namespace Mvc\App\Controller\Mod;

use Psr\Http\Message\{
    ResponseInterface,
    ServerRequestInterface,
};
use Mvc\App\Service\Mod\{
    AddMod As AddModService,
    Exception\ModAlreadyExists,
};
use Mvc\App\View\Mod\AddMod as AddModView;

class AddMod {

    /**
     * @param AddModView $addModView A view for presenting the response to the request back to the user.
     * @param AddModService $addModService An application service for adding a mod to the model layer.
     */
    public function __construct(
        private AddModView $addModView,
        private AddModService $addModService,
    ) {
        
    }

    /**
     * Add a mod.
     * 
     * The mod details are submitted from a form, using the HTTP method "POST".
     * 
     * @param ServerRequestInterface $request A server request.
     * @return ResponseInterface The response to the current request.
     */
    public function addMod(ServerRequestInterface $request): ResponseInterface {
        // Read the values submitted by the user.
        $name = $request->getParsedBody()['name'];
        $description = $request->getParsedBody()['description'];

        // Add the mod.
        try {
            $mod = $this->addModService->addMod($name, $description);
            $this->addModView->setMod($mod);
        } catch (ModAlreadyExists $exception) {
            $this->addModView->setErrorMessage(
                $exception->getMessage()
            );
        }

        // Present the results to the user.
        $response = $this->addModView->addMod();

        return $response;
    }

}

Mvc/App/Service/Mod/Exception/ModAlreadyExists.php:

<?php

namespace Mvc\App\Service\Mod\Exception;

/**
 * An exception thrown if a mod already exists.
 */
class ModAlreadyExists extends \OverflowException {
    
}

Mvc/App/Service/Mod/AddMod.php:

<?php

namespace Mvc\App\Service\Mod;

use Mvc\Domain\Model\Mod\{
    Mod,
    ModMapper,
};
use Mvc\App\Service\Mod\Exception\ModAlreadyExists;

/**
 * An application service for adding a mod.
 */
class AddMod {

    /**
     * @param ModMapper $modMapper A data mapper for transfering mods 
     * to and from a persistence system.
     */
    public function __construct(
        private ModMapper $modMapper
    ) {
        
    }

    /**
     * Add a mod.
     * 
     * @param string|null $name A mod name.
     * @param string|null $description A mod description.
     * @return Mod The added mod.
     */
    public function addMod(?string $name, ?string $description): Mod {
        $mod = $this->createMod($name, $description);

        return $this->storeMod($mod);
    }

    /**
     * Create a mod.
     * 
     * @param string|null $name A mod name.
     * @param string|null $description A mod description.
     * @return Mod The newly created mod.
     */
    private function createMod(?string $name, ?string $description): Mod {
        return new Mod($name, $description);
    }

    /**
     * Store a mod.
     * 
     * @param Mod $mod A mod.
     * @return Mod The stored mod.
     * @throws ModAlreadyExists The mod already exists.
     */
    private function storeMod(Mod $mod): Mod {
        if ($this->modMapper->modExists($mod)) {
            throw new ModAlreadyExists(
                    'A mod with the name "' . $mod->getName() . '" already exists'
            );
        }

        return $this->modMapper->saveMod($mod);
    }

}

Mvc/App/View/Mod/AddMod.php:

<?php

namespace Mvc\App\View\Mod;

use Mvc\{
    App\View\View,
    Domain\Model\Mod\Mod,
};
use Psr\Http\Message\ResponseInterface;

/**
 * A view for adding a mod.
 */
class AddMod extends View {

    /** @var Mod A mod. */
    private Mod $mod = null;

    /**
     * Add a mod.
     * 
     * @return ResponseInterface The response to the current request.
     */
    public function addMod(): ResponseInterface {
        $bodyContent = $this->templateRenderer->render('@Templates/Mod/AddMod.html.twig', [
            'activeNavItem' => 'AddMod',
            'mod' => $this->mod,
            'error' => $this->errorMessage,
        ]);

        $response = $this->responseFactory->createResponse();
        $response->getBody()->write($bodyContent);

        return $response;
    }

    /**
     * Set the mod.
     * 
     * @param Mod $mod A mod.
     * @return static
     */
    public function setMod(Mod $mod): static {
        $this->mod = $mod;
        return $this;
    }

}

Mvc/App/View/View.php:

<?php

namespace Mvc\App\View;

use Psr\Http\Message\ResponseFactoryInterface;
use SampleLib\Template\Renderer\TemplateRendererInterface;

/**
 * A view.
 */
abstract class View {

    /** @var string An error message */
    protected string $errorMessage = '';

    /**
     * @param ResponseFactoryInterface $responseFactory A response factory.
     * @param TemplateRendererInterface $templateRenderer A template renderer.
     */
    public function __construct(
        protected ResponseFactoryInterface $responseFactory,
        protected TemplateRendererInterface $templateRenderer
    ) {
        
    }

    /**
     * Set the error message.
     * 
     * @param string $errorMessage An error message.
     * @return static
     */
    public function setErrorMessage(string $errorMessage): static {
        $this->errorMessage = $errorMessage;
        return $this;
    }

}

Mvc/Domain/Infrastructure/Mod/PdoModMapper.php:

<?php

namespace Mvc\Domain\Infrastructure\Mod;

use Mvc\Domain\Model\Mod\{
    Mod,
    ModMapper,
};
use PDO;

/**
 * A data mapper for transfering Mod entities to and from a database.
 * 
 * This class uses a PDO instance as database connection.
 */
class PdoModMapper implements ModMapper {

    /**
     * @param PDO $connection Database connection.
     */
    public function __construct(
        private PDO $connection
    ) {
        
    }

    /**
     * @inheritDoc
     */
    public function modExists(Mod $mod): bool {
        $sql = 'SELECT COUNT(*) as cnt FROM mods WHERE name = :name';

        $statement = $this->connection->prepare($sql);
        $statement->execute([
            ':name' => $mod->getName(),
        ]);

        $data = $statement->fetch(PDO::FETCH_ASSOC);

        return ($data['cnt'] > 0) ? true : false;
    }

    /**
     * @inheritDoc
     */
    public function saveMod(Mod $mod): Mod {
        if (isset($mod->getId())) {
            return $this->updateMod($mod);
        }
        return $this->insertMod($mod);
    }

    /**
     * Update a mod.
     * 
     * @param Mod $mod A mod.
     * @return Mod The mod.
     */
    private function updateMod(Mod $mod): Mod {
        $sql = 'UPDATE mods 
                SET 
                    name = :name,
                    description = :description 
                WHERE 
                    id = :id';

        $statement = $this->connection->prepare($sql);
        $statement->execute([
            ':name' => $mod->getName(),
            ':description' => $mod->getDescription(),
        ]);

        return $mod;
    }

    /**
     * Insert a mod.
     * 
     * @param Mod $mod A mod.
     * @return Mod The newly inserted mod.
     */
    private function insertMod(Mod $mod): Mod {
        $sql = 'INSERT INTO mods (
                    name,
                    description
                ) VALUES (
                    :name,
                    :description
                )';

        $statement = $this->connection->prepare($sql);
        $statement->execute([
            ':name' => $mod->getName(),
            ':description' => $mod->getDescription(),
        ]);

        $mod->setId(
            $this->connection->lastInsertId()
        );

        return $mod;
    }

}

Mvc/Domain/Model/Mod/Mod.php:

<?php

namespace Mvc\Domain\Model\Mod;

/**
 * Mod entity.
 */
class Mod {

    /**
     * @param string|null $name (optional) A name.
     * @param string|null $description (optional) A description.
     */
    public function __construct(
        private ?string $name = null,
        private ?string $description = null
    ) {
        
    }

    /**
     * Get id.
     * 
     * @return int|null
     */
    public function getId(): ?int {
        return $this->id;
    }

    /**
     * Set id.
     * 
     * @param int|null $id An id.
     * @return static
     */
    public function setId(?int $id): static {
        $this->id = $id;
        return $this;
    }

    /**
     * Get the name.
     * 
     * @return string|null
     */
    public function getName(): ?string {
        return $this->name;
    }

    /**
     * Set the name.
     * 
     * @param string|null $name A name.
     * @return static
     */
    public function setName(?string $name): static {
        $this->name = $name;
        return $this;
    }

    /**
     * Get the description.
     * 
     * @return string|null
     */
    public function getDescription(): ?string {
        return $this->description;
    }

    /**
     * Set the description.
     * 
     * @param string|null $description A description.
     * @return static
     */
    public function setDescription(?string $description): static {
        $this->description = $description;
        return $this;
    }

}

Mvc/Domain/Model/Mod/ModMapper.php:

<?php

namespace Mvc\Domain\Model\Mod;

use Mvc\Domain\Model\Mod\Mod;

/**
 * An interface for various data mappers used to 
 * transfer Mod entities to and from a persistence system.
 */
interface ModMapper {

    /**
     * Check if a mod exists.
     * 
     * @param Mod $mod A mod.
     * @return bool True if the mod exists, false otherwise.
     */
    public function modExists(Mod $mod): bool;

    /**
     * Save a mod.
     * 
     * @param Mod $mod A mod.
     * @return Mod The saved mod.
     */
    public function saveMod(Mod $mod): Mod;
}