Good practices for growing class

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Good practices for growing class

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#1 by (2 votes)

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Complementing a question that I posted here for some time, about a system for registering users using SOLID standard concepts, one of the problem I came across was the question of the User class being very large and can be very variable, one Once a user can have several characteristics, it follows a situation "script":

Each attribute has its setter / getter in the User class.
Each attribute has its validation rule in the userValidator class.
Each attribute has its "definition" in an associative array of the class userCrud.

Let's say that in another situation a user might have attributes like: corDOSOlhos, corDoCabelo and etc, I would have to always be changing the classes above, what would be a good solution for this?

User class structure:

class User {

private $attributes;

function __construct() {
    $this->userValidator = new userValidator;
}

function setName ($param) {

    if($this->userValidator->validateName($param))
        $this->attributes['name'] = $param;
}

function getAttributes () {
    return $this->attributes;
}

function getAttribute ($attr) {

    if(isset($attributes[$attr]))
        return $this->attributes[$name];
    else throw new Exception("Attribute '{$attr}' does not exist");

}

}

php solid

asked by anonymous 01.10.2018 / 20:18

1 answer

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Validation

To validate each attribute it is best to have a validator for each value. With this in mind, if a new attribute arises it is not necessary to modify the class.

Basically, validators will be passed to a primary validator:

class UserValidator
{

   private $validators = [];

   public function setValidator($attribute, $validator)
   {

      $this->validator[$attribute] = $validator;

   }

   public function validate(User $user)
   {

       $messages = [];

       foreach($user->getData() as $attribute => $value){

           // Verificando se um validador para o atributo existe
           if(isset($this->validators[$attribute])){
               $message = $this->validators[$attribute]->validate($value);

               // Caso contenha a mensagem de validação, ela será armazenada em um array
               if($message){
                  $messages[$attribute] = $message;
               }

           }

       }

       // Retornando as mensagens de validação para serem utilizadas
       return $messages;

   }

 }

Using the UserValidator

To use the class you will need to pass the validators to it. As you can see, to add a new validation just set the class with the setValidator method.

$userValidator = new UserValidador;
$userValidator->serValidator('name', new NameValidator);
$userValidator->setValidator('age', new AgeValidator);
$userValidator->setValidator('corDosOlhos', new CorDosOlhosValidator);
// Basta continuar configurando para cada novo atributo necessário.

The User entity

Finally, the User entity would work with an array to avoid having a huge amount of methods. If a new attribute is added, the class remains intact. Here's the implementation:

class User
{

   private $attributes;

   public function __construct(array $attributes){

       $this->attributes = $attributes;

   }

   public function getData()
   {

      return $this->attributes;

   }

   // Exemplo de método que pode ser utilizado em outros contextos
   public function getUserAttribute($attribute){

       if(isset($this->attributes[$attribute])){
           return $this->attributes[$attribute];
       }

       throw new Exception('Attribute not found');

   }

}

Final considerations

Before finishing I would like to point out some points:

If the attributes grow, simply add a new item in the array passed to User and a new validator for this item.
As you can see, the classes will not be modified. The additions will be made in the configuration of the objects.