我为自定义电子邮件类型复制了 Lighthouse 网站链接到 ( https://webonyx.github.io/graphql-php/type-system/scalar-types/ ) 的示例。（见下面的代码）
不幸的是，如果我现在转到 graphql-playground，我会收到 500 错误，说明：“没有为标量电子邮件找到 GraphQL\Type\Definition\ScalarType 的匹配子类”
我该如何解决这个错误？
<?php
// file: /graphql/EmailType.php
namespace MyApp;
use GraphQL\Error\Error;
use GraphQL\Error\InvariantViolation;
use GraphQL\Language\AST\StringValueNode;
use GraphQL\Type\Definition\ScalarType;
use GraphQL\Utils\Utils;
class EmailType extends ScalarType
{
// Note: name can be omitted. In this case it will be inferred from class name
// (suffix "Type" will be dropped)
public $name = 'Email';
/**
* Serializes an internal value to include in a response.
*
* @param string $value
* @return string
*/
public function serialize($value)
{
// Assuming internal representation of email is always correct:
return $value;
}
/**
* Parses an externally provided value (query variable) to use as an input
*
* @param mixed $value
* @return mixed
*/
public function parseValue($value)
{
if (!filter_var($value, FILTER_VALIDATE_EMAIL)) {
throw new Error("Cannot represent following value as email: " . Utils::printSafeJson($value));
}
return $value;
}
/**
* Parses an externally provided literal value (hardcoded in GraphQL query) to use as an input.
*
* E.g.
* {
* user(email: "user@example.com")
* }
*
* @param \GraphQL\Language\AST\Node $valueNode
* @param array|null $variables
* @return string
* @throws Error
*/
public function parseLiteral($valueNode, array $variables = null)
{
// Note: throwing GraphQL\Error\Error vs \UnexpectedValueException to benefit from GraphQL
// error location in query:
if (!$valueNode instanceof StringValueNode) {
throw new Error('Query error: Can only parse strings got: ' . $valueNode->kind, [$valueNode]);
}
if (!filter_var($valueNode->value, FILTER_VALIDATE_EMAIL)) {
throw new Error("Not a valid email", [$valueNode]);
}
return $valueNode->value;
}
}