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youshido-php/GraphQL: Pure PHP realization of GraphQL protocol

原作者: [db:作者] 来自: 网络 收藏 邀请

开源软件名称（OpenSource Name）：

youshido-php/GraphQL

开源软件地址(OpenSource Url)：

https://github.com/youshido-php/GraphQL

开源编程语言(OpenSource Language)：

PHP 100.0%

开源软件介绍(OpenSource Introduction)：

Looking for Maintainers!

Unfortunatelly, we cannot longer support this package and are looking for someone to take the ownership. Currently Only PRs with bugfixes and not breaking BC are being merged. It's very sad to acknowledge this, but we hope that someone can take it further with the community.

Please, PM @viniychuk if you are interested in taking over.

GraphQL

Join the chat at https://gitter.im/Youshido/GraphQL Latest Stable Version Build Status Scrutinizer Code Quality Code Coverage SensioLabsInsight

This is a pure PHP realization of the GraphQL protocol based on the working draft of the official GraphQL Specification located on http://facebook.github.io/graphql/.

GraphQL is a query language for APIs. It brings a new paradigm to the world of client-server communication and delivers a much more predictable behavior and smallest possible over-the-wire responses to any request. GraphQL advanced in many ways and has fundamental quality improvements:

  • strongly typed communication protocol makes both client and server predictable and more stable
  • encourages you to build a constantly evolving APIs and not use versions in the endpoints
  • bulk requests and responses to avoiding waiting for multiple HTTP handshakes
  • easily generated documentation and incredibly intuitive way to explore created API
  • clients will be much less likely to require backend changes

Current package is and will be trying to be kept up to date with the latest revision of the official GraphQL Specification which is now of April 2016.

Symfony bundle is available by the link – http://github.com/Youshido/GraphqlBundle

If you have any questions or suggestions – let's talk on GraphQL Gitter channel

Table of Contents

Getting Started

You should be better off starting with some examples and "Star Wars" become a somewhat "Hello world" for the GraphQL implementations. If you're looking just for that – you can get it via this link – Star Wars example. On the other hand, we prepared a step-by-step guide for those who wants to get up to speed bit by bit.

Installation

Install GraphQL package using composer. If you're not familiar with it, you should check out their manual. Run composer require youshido/graphql.

Alternatively you can run the following commands:

mkdir graphql-test && cd graphql-test
composer init -n
composer require youshido/graphql

Now you're ready to create your GraphQL Schema and check if everything works fine. Your first GraphQL app will be able to receive currentTime request and response with a formatted time string.

you can find this example in the examples directory – 01_sandbox.

Create an index.php file with the following content:

<?php
namespace Sandbox;

use Youshido\GraphQL\Execution\Processor;
use Youshido\GraphQL\Schema\Schema;
use Youshido\GraphQL\Type\Object\ObjectType;
use Youshido\GraphQL\Type\Scalar\StringType;

require_once 'vendor/autoload.php';

$processor = new Processor(new Schema([
    'query' => new ObjectType([
        'name' => 'RootQueryType',
        'fields' => [
            'currentTime' => [
                'type' => new StringType(),
                'resolve' => function() {
                    return date('Y-m-d H:ia');
                }
            ]
        ]
    ])
]));

$processor->processPayload('{ currentTime }');
echo json_encode($processor->getResponseData()) . "\n";

You can now execute php index.php and get a response with your current time:

{
   data: { currentTime: "2016-05-01 19:27pm" }
}

Just like that, you have created a GraphQL Schema with a field currentTime of type String and resolver for it. Don't worry if you don't know what the field, type and resolver mean here, you'll learn along the way.

If you're having any troubles – here're some troubleshooting points:

  • check that you have the latest composer version (composer self-update)
  • make sure your index.php file has been created in the same directory that you have vendor folder in (presumably it's graphql-test folder)
  • last but not least, check that you have php-cli installed and running and it's version >= 5.5 (php -v)

Also, you can always check if script from the examples folder work.

Tutorial – Creating Blog Schema

For our learning example we'll architect a GraphQL Schema for a Blog. You'll probably be using our package along with your favorite framework (we have a Symfony version here), but for the purpose of this tutorial we're keeping it all examples as plain php code.

(Complete example of the Blog schema available by the following link https://github.com/Youshido/GraphQL/tree/master/examples/02_blog)

Our Blog will have Users who can write Posts and leave Comments. Also, there will be a LikePost operation that could be performed by anyone. Let's start with Post. Take a look at the query that returns title and summary of the latest Post:

GraphQL query is a simple text query structured very much similar to the json format.

latestPost {
    title,
    summary
}

Supposedly server should reply with a relevant json response:

{
   data: {
       latestPost: {
           title: "This is a post title",
           summary: "This is a post summary"
       }
   }
}

It looks very simple and straight forward, so let's go ahead and write code that can handle this request.

Creating Post schema

We'll take a quick look on different approaches you can use to define your schema. Each of them has it's own pros and cons, inline approach might seem to be easier and faster when object oriented gives you more flexibility and freedom as your project grows. You should definitely use OOP approach every time you can reuse the type you're creating.

We're going to create RootQueryType with one field latestPost. Every GraphQL Field has a type(e.g. String, Int, Boolean) and it could be of a different kind(e.g. Scalar, Enum, List). You can read more about it in the official documentation, but for now you can think of field of a type like about instance of a class.

Inline approach

You can create inline-index.php file in your project folder and paste the following code there

inline-index.php

<?php
namespace InlineSchema;

use Youshido\GraphQL\Execution\Processor;
use Youshido\GraphQL\Schema\Schema;
use Youshido\GraphQL\Type\Object\ObjectType;
use Youshido\GraphQL\Type\Scalar\StringType;

// including autoloader
require_once __DIR__ . '/vendor/autoload.php';

// instantiating Processor and setting the schema
$processor = new Processor(new Schema([
    'query' => new ObjectType([
        // root query by convention has a name RootQueryType
        'name'   => 'RootQueryType',
        'fields' => [
            'latestPost' => [
                'type'    => new ObjectType([ // Post type is being created as ObjectType
                    'name'    => 'Post', // name of our type – "Post"
                    'fields'  => [
                        'title'   => new StringType(),  // defining "title" field, type - String
                        'summary' => new StringType(),  // defining "summary" field, type - String
                    ],
                ]),
                'resolve' => function () {          // resolver for latestPost field
                    return [                        // for now it returns a static array with data
                        "title"   => "New approach in API has been revealed",
                        "summary" => "In two words - GraphQL Rocks!",
                    ];
                }
            ]
        ]
    ])
]));

// creating payload and running it through processor
$payload = '{ latestPost { title, summary } }';
$processor->processPayload($payload);
// displaying result
echo json_encode($processor->getResponseData()) . "\n";

To check if everything is working – execute inline-index.php: php inline-index.php You should see response as the json encoded object latestPost inside the data section:

{
   data: {
       latestPost: {
           title: "New approach in API has been revealed",
           summary: "In two words - GraphQL Rocks!"
       }
   }
}

Try to play with the code by removing one field from the request or by changing the resolve function.

Object oriented approach

It's a common situation when you need to use the same custom type in different places, so we're going to create a separate class for the PostType and use it in our GraphQL Schema. To keep everything structured we're going to put this and all our future classes into the Schema folder.

Create a file Schema/PostType.php and put the following code in there:

<?php
namespace Examples\Blog\Schema;

use Youshido\GraphQL\Type\Object\AbstractObjectType;
use Youshido\GraphQL\Type\Scalar\StringType;

class PostType extends AbstractObjectType   // extending abstract Object type
{

    public function build($config)  // implementing an abstract function where you build your type
    {
        $config
            ->addField('title', new StringType())       // defining "title" field of type String
            ->addField('summary', new StringType());    // defining "summary" field of type String
    }

    public function getName()
    {
        return "Post";  // if you don't do getName – className without "Type" will be used
    }

}

Now let's create the main entry point for this example – index.php:

<?php

namespace Examples\Blog;

use Examples\Blog\Schema\PostType;
use Youshido\GraphQL\Execution\Processor;
use Youshido\GraphQL\Schema\Schema;
use Youshido\GraphQL\Type\Object\ObjectType;

require_once __DIR__ . '/vendor/autoload.php';
require_once __DIR__ . '/Schema/PostType.php';       // including PostType definition

$rootQueryType = new ObjectType([
    'name' => 'RootQueryType',
    'fields' => [
        'latestPost' => [
            'type'    => new PostType(),
            'resolve' => function ($source, $args, $info)
            {
                return [
                    "title"   => "New approach in API has been revealed",
                    "summary" => "In two words - GraphQL Rocks!",
                ];
            }
        ]
    ]
]);

$processor = new Processor(new Schema([
    'query' => $rootQueryType
]));
$payload = '{ latestPost { title, summary } }';

$processor->processPayload($payload);
echo json_encode($processor->getResponseData()) . "\n";

Ensure everything is working properly by running php index.php. You should see the same response you saw for the inline approach.

Next step would be to create a separate class for the latestPostField by extending AbstractField class: Schema/LatestPostField.php

<?php

namespace Examples\Blog\Schema;

use Youshido\GraphQL\Execution\ResolveInfo;
use Youshido\GraphQL\Field\AbstractField;

class LatestPostField extends AbstractField
{
    public function getType()
    {
        return new PostType();
    }

    public function resolve($value, array $args, ResolveInfo $info)
    {
        return [
            "title"   => "New approach in API has been revealed",
            "summary" => "In two words - GraphQL Rocks!",
        ];
    }
}

And now we can update our index.php:

<?php

namespace Examples\Blog;

use Examples\Blog\Schema\LatestPostField;
use Youshido\GraphQL\Execution\Processor;
use Youshido\GraphQL\Schema\Schema;
use Youshido\GraphQL\Type\Object\ObjectType;

require_once __DIR__ . '/vendor/autoload.php';
require_once __DIR__ . '/Schema/PostType.php';       // including PostType definition
require_once __DIR__ . '/Schema/LatestPostField.php';

$rootQueryType = new ObjectType([
    'name' => 'RootQueryType',
    'fields' => [
        new LatestPostField()
    ]
]);

$processor = new Processor(new Schema([
    'query' => $rootQueryType
]));
$payload = '{ latestPost { title, summary } }';

$processor->processPayload($payload);
echo json_encode($processor->getResponseData()) . "\n";

Choosing approach for your project

We would recommend to stick to object oriented approach for the several reasons (that matter the most for the GraphQL specifically):

  • makes your Types reusable
  • adds an ability to refactor your schema using IDEs
  • autocomplete to help you avoid typos
  • much easier to navigate through your Schema when project grows

With that being said, we use inline approach a lot to explore and bootstrap ideas or to develop simple fields/resolver that are going to be used in one place only. With the inline approach you can be fast and agile in creating mock-data server to test your frontend or mobile client.

Use valid Names
We highly recommend to get familiar with the official GraphQL Specification Remember that valid identifier in GraphQL should follow the pattern /[_A-Za-z][_0-9A-Za-z]*/. That means any identifier should consist of a latin letter, underscore, or a digit and cannot start with a digit. Names are case sensitive

We'll continue to work on the Blog Schema to explore all essentials details of developing GraphQL server.

Query Documents

In GraphQL terms – query document describe a complete request received by GraphQL service. It contains list of Operations and Fragments. Both are fully supported by our PHP library. There are two types of Operations in GraphQL:

  • Query – a read only request that is not supposed to do any changes on the server
  • Mutation – a request that changes(mutate) data on the server followed by a data fetch

You've already seen examples of Query with latestPost and currentTime, so let's define a simple Mutation that will provide API to Like the Post. Here's sample request and response of likePost mutation:

request

mutation {
  likePost(id: 5)
}

response

{
  data: { likePost: 2 }
}

Any Operation has a response type and in this case the likePost mutation type is Int

Note, that the response type of this mutation is a scalar Int. Of course in real life you'll more likely have a response of type Post for such mutation, but we're going to implement code for a simple example above and even keep it inside index.php:

<?php

namespace Examples\Blog;

use Examples\Blog\Schema\LatestPostField;
use Youshido\GraphQL\Execution\Processor;
use Youshido\GraphQL\Schema\Schema;
use Youshido\GraphQL\Type\NonNullType;
use Youshido\GraphQL\Type\Object\ObjectType;
use Youshido\GraphQL\Type\Scalar\IntType;

require_once __DIR__ . '/vendor/autoload.php';
require_once __DIR__ . '/Schema/PostType.php';       // including PostType definition
require_once __DIR__ . '/Schema/LatestPostField.php';

$rootQueryType = new ObjectType([
    'name'   => 'RootQueryType',
    'fields' => [
        new LatestPostField()
    ]
]);

$rootMutationType = new ObjectType([
    'name'   => 'RootMutationType',
    'fields' => [
        // defining likePost mutation field
        'likePost' => [
            // we specify the output type – simple Int, since it doesn't have a structure
            'type'    => new IntType(),
            // we need a post ID and we set it to be required Int
            'args'    => [
                'id' => new NonNullType(new IntType())
            ],
            // simple resolve function that always returns 2
            'resolve' => function () {
                return 2;
            },
        ]
    ]
]);

$processor = new Processor(new Schema([
    'query'    => $rootQueryType,
    'mutation' => $rootMutationType
]));
$payload   = 'mutation { likePost(id: 5) }';

$processor->processPayload($payload);
echo json_encode($processor->getResponseData()) . "\n";

Run php index.php, you should see a valid response:

{"data":{"likePost":2}}

Now, let's make our likePost mutation to return the whole Post as a result. First, we'll add likesCount field to the PostType:

<?php
namespace Examples\Blog\Schema;

use Youshido\GraphQL\Type\Object\AbstractObjectType;
use Youshido\GraphQL\Type\Scalar\IntType;
use Youshido\GraphQL\Type\Scalar\StringType;

class PostType extends AbstractObjectType
{

    public function build($config)
    {
        // you can define fields in a single addFields call instead of chaining multiple addField()
        $config->addFields([
            'title'      => new StringType(),
            'summary'    => new StringType(),
            'likesCount' => new IntType()
        ]);
    }

    // Since our class named by a convention, we can remove getName() method
}

Secondly, modify resolve function in LatestPostField:

public function resolve($value, array $args, ResolveInfo $info)
{
    return [
        "title"      => "New approach in API has been revealed",
        "summary"    => "In two words - GraphQL Rocks!",
        "likesCount" => 2
    ];
}

Lastly, we're going to change Mutation Type from IntType to PostType and update the resolve function to be compliant with the the new type and update the request:

<?php
// ...
$rootMutationType = new ObjectType([
    'name'   => 'RootMutationType',
    'fields' => [
        'likePost' => [
            'type'    => new PostType(),
            'args'    => [
                'id' => new NonNullType(new IntType())
            ],
            'resolve' => function () {
                return [
                    'title'     => 'New approach in API has been revealed',
                    'summary'   => 'In two words - GraphQL Rocks!',
                    'likesCount' => 2
                ];
            },
        ]
    ]
]);
// ...
$payload   = 'mutation { likePost(id: 5) { title, likesCount } }';
//...

Execute php index.php, you should see title and likesCount in response. We can now try to use id: 5 that we're passing as a parameter to our mutation:

$rootMutationType = new ObjectType([
    'name'   => 'RootMutationType',
    'fields' => [
        'likePost' => [
            'type'    => new PostType(),
            'args'    => [
                'id' => new NonNullType(new IntType())
            ],
            'resolve' => function ($source, $args, $resolveInfo) {
                return [
                    'title'      => 'Title for the post #' . $args['id'], // we can be sure that $args['id'] is always set
                    'summary'    => 'In two words - GraphQL Rocks!',
                    'likesCount' => 2
                ];
            },
        ]
    ]
]);

Now you have a basic understanding of how queries and mutations are structured and ready to move on to the details of the GraphQL Type System and PHP-specific features of the GraphQL server architecture.

Type System

Type is an atom of definition in GraphQL Schema. Every field, object, or argument has a type. GraphQL is a strongly typed language. There are system types and custom types defined specifically for the application, in our app we'll have custom types Post, User, Comment, etc. Your custom types are usually built on top of GraphQL system types.

Scalar Types

List of GraphQL Scalar types: