graphql-php入门：如何从.graphql文件向架构添加解析器功能？

getting started in graphql-php: how to add resolver functions to schema from .graphql file?

我是GraphQL的新手，并且想与graphql-php一起使用，以构建一个入门的简单API。我目前正在阅读文档并尝试使用示例，但是起初我很困惑。

我希望将架构存储在schema.graphql文件中，而不是手动进行构建，因此我遵循了有关如何执行此操作的文档，确实可以正常工作：

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<?php
// graph-ql is installed via composer
require('../vendor/autoload.php');

use GraphQL\\Language\\Parser;
use GraphQL\\Utils\\BuildSchema;
use GraphQL\\Utils\\AST;
use GraphQL\\GraphQL;

try {
$cacheFilename = 'cached_schema.php';
// caching, as recommended in the docs, is disabled for testing
// if (!file_exists($cacheFilename)) {
$document = Parser::parse(file_get_contents('./schema.graphql'));
file_put_contents($cacheFilename,"<?php\
return" . var_export(AST::toArray($document), true) . ';');
/*} else {
$document = AST::fromArray(require $cacheFilename); // fromArray() is a lazy operation as well
}*/

$typeConfigDecorator = function($typeConfig, $typeDefinitionNode) {
// In the docs, this function is just empty, but I needed to return the $typeConfig, otherwise I got an error
return $typeConfig;
};
$schema = BuildSchema::build($document, $typeConfigDecorator);

$context = (object)array();

// this has been taken from one of the examples provided in the repo
$rawInput = file_get_contents('php://input');
$input = json_decode($rawInput, true);
$query = $input['query'];
$variableValues = isset($input['variables']) ? $input['variables'] : null;
$rootValue = ['prefix' => 'You said: '];
$result = GraphQL::executeQuery($schema, $query, $rootValue, $context, $variableValues);
$output = $result->toArray();
} catch (\\Exception $e) {
$output = [
'error' => [
'message' => $e->getMessage()
]
];
}
header('Content-Type: application/json; charset=UTF-8');
echo json_encode($output);

这是我的schema.graphql文件的样子：

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schema {
query: Query
}

type Query {
products: [Product!]!
}

type Product {
id: ID!,
type: ProductType
}

enum ProductType {
HDRI,
SEMISPHERICAL_HDRI,
SOUND
}

我可以例如查询

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query {
__schema {types{name}}
}

并且这将按预期返回元数据。但是，当然，现在我想查询实际的产品数据，并从数据库中获取数据，为此，我需要定义一个解析器功能。

http://webonyx.github.io/graphql-php/type-system/type-language/上的文档说明："默认情况下，这种架构是在没有任何解析器的情况下创建的。我们必须依靠默认字段解析器和根值以便针对该架构执行查询。" -但是没有这样做的例子。

如何为每种类型/字段添加解析器功能？

相关讨论

此方法无需实例化服务器即可工作。就我而言，我已经有一个服务器并且可以读取HTTP数据，我所需要做的就是读取GraphQL模式并运行查询。首先，我从文件中读取模式：

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$schemaContent = // file_get_contents or whatever works for you

$schemaDocument = GraphQL\\Language\\Parser::parse($schemaContent);
$schemaBuilder = new GraphQL\\Utils\\BuildSchema($schemaDocument);
$schema = $schemaBuilder->buildSchema();

然后，我通过自定义字段解析器执行查询：

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$fieldResolver = function() {
return call_user_func_array([$this, 'defaultFieldResolver'], func_get_args());
};

$result = GraphQL\\GraphQL::executeQuery(
$schema,
$query, // this was grabbed from the HTTP post data
null,
$appContext, // custom context
$variables, // this was grabbed from the HTTP post data
null,
$fieldResolver // HERE, custom field resolver
);

字段解析器如下所示：

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private static function defaultFieldResolver(
$source,
$args,
$context,
\\GraphQL\\Type\\Definition\
esolveInfo $info
) {
$fieldName = $info->fieldName;
$parentType = $info->parentType->name;

if ($source === NULL) {
// this is the root value, return value depending on $fieldName
// ...
} else {
// Depending on field type ($parentType), I call different field resolvers.
// Since our system is big, we implemented a bootstrapping mechanism
// so modules can register field resolvers in this class depending on field type
// ...

// If no field resolver was defined for this $parentType,
// we just rely on the default field resolver provided by graphql-php (copy/paste).
$fieldName = $info->fieldName;
$property = null;

if (is_array($source) || $source instanceof \\ArrayAccess) {
if (isset($source[$fieldName])) {
$property = $source[$fieldName];
}
} else if (is_object($source)) {
if (isset($source->{$fieldName})) {
$property = $source->{$fieldName};
}
}

return $property instanceof \\Closure
? $property($source, $args, $context)
: $property;
}
}

这就是我最终要做的...

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$rootResolver = array(
'emptyCart' => function($root, $args, $context, $info) {
global $rootResolver;
initSession();
$_SESSION['CART']->clear();
return $rootResolver['getCart']($root, $args, $context, $info);
},
'addCartProduct' => function($root, $args, $context, $info) {
global $rootResolver;

...

return $rootResolver['getCart']($root, $args, $context, $info);
},
'removeCartProduct' => function($root, $args, $context, $info) {
global $rootResolver;

...

return $rootResolver['getCart']($root, $args, $context, $info);
},
'getCart' => function($root, $args, $context, $info) {
initSession();
return array(
'count' => $_SESSION['CART']->quantity(),
'total' => $_SESSION['CART']->total(),
'products' => $_SESSION['CART']->getProductData()
);
},

然后在配置中

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$config = ServerConfig::create()
->setSchema($schema)
->setRootValue($rootResolver)
->setContext($context)
->setDebug(DEBUG_MODE)
->setQueryBatching(true)
;

$server = new StandardServer($config);

在我看来，这有点hacking，我可能应该将解析程序外包到单独的文件中，但是它可以正常工作……仍然感到困惑的是，没有简单的示例可以完成此任务，也许比我的解决方案更好。

我为此使用根值：

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<?php

require("vendor/autoload.php") ;
require("exemplo-graphql.php");
require("Usuario.php");

use GraphQL\\GraphQL;
use GraphQL\\Type\\Schema;
use GraphQL\\Utils\\BuildSchema;

$query = $_REQUEST['query'];

$typeConfigDecorator = function($typeConfig, $typeDefinitionNode) {
$name = $typeConfig['name'];
// ... add missing options to $typeConfig based on type $name
return $typeConfig;
};

$contents = file_get_contents('schema.graphql');
$schema = BuildSchema::build($contents, $typeConfigDecorator);

// $rawInput = file_get_contents('php://input');
$input = json_decode($query, true);
$query = $input['query'];
$variableValues = isset($input['variables']) ? $input['variables'] : null;

try {
// $rootValue = ['prefix' => 'You said: '];
$rootValue = [
'usuario' => function($root, $args, $context, $info) {
$usuario = new Usuario();
$usuario->setNome("aqui tem um teste");
$usuario->setEmail("aqui tem um email");
return $usuario;
},
'echo' => function($root, $args, $context, $info) {
return"aqui tem um echooo";
},
'adicionarUsuario' => function ($root, $args, $context, $info) {
$usuario = new Usuario();
$usuario->setNome("aqui tem um teste");
$usuario->setEmail("aqui tem um email");
return $usuario;
}
];

$result = GraphQL::executeQuery($schema, $query, $rootValue, null,
$variableValues);

if ($result->errors) {
$output = [
'errors' => [
[
'message' => $result->errors
]
]
];
} else {
$output = $result->toArray();
}
} catch (\\Exception $e) {
$output = [
'errors' => [
[
'message' => $e->getMessage()
]
]
];
}

header('Content-Type: application/json');
echo json_encode($output);