FactoryPattern.php

<?php

interface DataType
{
    /**
     * @return mixed
     */
    public function getModel();
}

class StringType implements DataType
{
    /**
     * @var array
     */
    public $model;

    /**
     * StringType constructor.
     * @param array $model
     */
    public function __construct(array $model)
    {
        $this->model = $model;
    }

    /**
     * @return mixed|string
     */
    public function getModel()
    {
        return implode(", ", $this->model);
    }
}

class JsonType implements DataType
{
    /**
     * @var array
     */
    public $model;

    /**
     * JsonType constructor.
     * @param array $model
     */
    public function __construct(array $model)
    {
        $this->model = $model;
    }

    /**
     * @return false|string
     */
    public function getModel()
    {
        return json_encode($this->model, true);
    }
}

class TypeFactory
{
    /**
     * @var array
     */
    public $model;

    /**
     * TypeFactory constructor.
     * @param array $model
     */
    public function __construct(array $model)
    {
        $this->model = $model;
    }

    /**
     * @param string $type
     * @return DataType
     */
    public function setType(string $type) : DataType
    {
        switch ($type) {
            case "Json":
                return new JsonType($this->model);
            case "String":
                return new StringType($this->model);
        }
    }
}

class Client
{
    public function getResponse()
    {
        $model = array(
            "name" => "Jane",
            "age" => 31
        );

        $typeCreator = new TypeFactory($model);
        $response = $typeCreator->setType("String");
        return $response->getModel();
    }
}