在 PHP 7.4 中获取类型属性

Question

我有一个 DTO 类型的 PHP 变量：

class CreateMembershipInputDto extends BaseDto
{
    public bool $is_gift;
    public int $year;
    public string $name;
    public \DateTime $shipping_date;
    public ContactInputDto $buyer;
    public ?ContactInputDto $receiver;
}

我正在尝试制作某种填充属性的自动映射器，但我需要检查变量的类型，但这似乎是不可能的。

class BaseDto
{
    public function __construct($json)
    {
        $jsonArray = json_decode($json, true);
        foreach($jsonArray as $key=>$value){
            $type = gettype($this->$key);
            if($type instanceof BaseDto)
                $this->$key = new $type($value);
            else
                $this->$key = $value;
        }
    }
}

ContactInputDto:

class ContactInputDto extends BaseDto
{
    public string $firstname;
    public string $lastname;
    public string $street_housenumber;
    public string $postal_code;
    public string $place;
    public string $country;
    public string $email;
    public string $phone;
}

是否有可能使 "gettype($this->$key)" 行正常工作，而不 php 抛出以下错误：

Typed property App\Dto\CreateMembershipInputDto::$is_gift must not be accessed before initialization

Answer 1

虽然手册目前似乎没有记载，但 ReflectionProperty to allow you to get the type. This is actually specified in the RFC for typed properties

中添加了一种方法

以下是您将如何使用它：

class CreateMembershipInputDto extends BaseDto {
    public bool $is_gift;
    public int $year;
    public string $name;
    public \DateTime $shipping_date;
    public ContactInputDto $buyer;
    public ?ContactInputDto $receiver;
}

class BaseDto
{
    public function __construct($json)
    {   
        $r = new \ReflectionClass(static::class); //Static should resolve the the actual class being constructed
        $jsonArray = json_decode($json, true);
        foreach($jsonArray as $key=>$value){
            $prop = $r->getProperty($key);
            if (!$prop || !$prop->getType()) { continue; } // Not a valid property or property has no type   
            $type = $prop->getType();
            if($type->getName() === BaseDto::class) //types names are strings
                $this->$key = new $type($value);
            else
                $this->$key = $value;
        }
    }
}

如果你想检查类型是否扩展 BaseDto 你将需要 (new \ReflectionClass($type->getName()))->isSubclassOf(BaseDto::class)

注意getName指的是ReflectionNamedType::getName. Prior to PHP 8 this was the only possible instance you could get $prop->getType() however starting PHP 8 you may also get a ReflectionUnionType包含多个类型

在 PHP 7.4 中获取类型属性

Get type of typed property in PHP 7.4

php

php-7.4

在 PHP 7.4 中获取类型 属性

Get type of typed property in PHP 7.4

php

php-7.4

在 PHP 7.4 中获取类型属性