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nicolasdao/graphql-s2s: Add GraphQL Schema support for type inheritance, generic ...

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开源软件名称（OpenSource Name）：

nicolasdao/graphql-s2s

开源软件地址(OpenSource Url)：

https://github.com/nicolasdao/graphql-s2s

开源编程语言(OpenSource Language)：

JavaScript 99.7%

开源软件介绍(OpenSource Introduction)：

This project is still maintained but has been superseded by graphql-schemax. graphql-schemax takes the approach of compiling standard JSON object into a GraphQL Schema string.

GraghQL Schema-2-Schema Transpiler · NPM Tests License Neap npm downloads

Table Of Contents

What It Does

GraphQL S2S enriches the standard GraphQL Schema string used by both graphql.js and the Apollo Server. The enriched schema supports:

Install

node

npm install graphql-s2s --save

browser

<script src="https://unpkg.com/[email protected]/lib/graphqls2s.min.js"></script>

Using the awesome unpkg.com, all versions are supported at https://unpkg.com/graphql-s2s@:VERSION/lib/graphqls2s.min.js. The API will be accessible through the graphqls2s object.

It is also possible to embed it after installing the graphql-s2s npm package:

<script src="./node_modules/graphql-s2s/lib/graphqls2s.min.js"></script>

Getting Started

Basic

const { transpileSchema } = require('graphql-s2s').graphqls2s
const { makeExecutableSchema } = require('graphql-tools')

const schema = `
type Node {
	id: ID!
}

type Person inherits Node {
	firstname: String
	lastname: String
}

type Student inherits Person {
	nickname: String
}

type Query {
  students: [Student]
}
`

const resolver = {
        Query: {
            students(root, args, context) {
            	// replace this dummy code with your own logic to extract students.
                return [{ id: 1, firstname: "Carry", lastname: "Connor", nickname: "Cannie" }]
            }
        }
    };

const executableSchema = makeExecutableSchema({
  typeDefs: [transpileSchema(schema)],
  resolvers: resolver
})

Type Inheritance

Single Inheritance

const schema = `
type Node {
	id: ID!
}

# Inheriting from the 'Node' type
type Person inherits Node {
	firstname: String
	lastname: String
}

# Inheriting from the 'Person' type
type Student inherits Person {
	nickname: String
}
`

Multiple Inheritance

const schema = `

type Node {
	id: ID!
}

type Address {
	streetAddress: String
	city: String
	state: String
}

# Inheriting from the 'Node' & 'Adress' type
type Person inherits Node, Address {
	id: ID!
	streetAddress: String
	city: String
	state: String
	firstname: String
	lastname: String
}

`

More details in the code below.

Generic Types

const schema = `
# Defining a generic type
type Paged<T> {
	data: [T]
	cursor: ID
}

type Question {
	name: String!
	text: String!
}

# Using the generic type
type Student {
	name: String
	questions: Paged<Question>
}

# Using the generic type
type Teacher {
	name: String
	students: Paged<Student>
}
`

More details in the code below.

Metadata Decoration

const schema = `
# Defining a custom 'node' metadata attribute
@node
type Node {
	id: ID!
}

type Student inherits Node {
	name: String

	# Defining another custom 'edge' metadata, and supporting a generic type
	@edge(some other metadata using whatever syntax I want)
	questions: [String]
}
`

The enriched schema provides a richer and more compact notation. The transpiler converts the enriched schema into the standard expected by graphql.js (using the buildSchema method) as well as the Apollo Server. For more details on how to extract those extra information from the string schema, use the method getSchemaAST (example in section Metadata Decoration).

Metadata can be added to decorate the schema types and properties. Add whatever you want as long as it starts with @ and start hacking your schema. The original intent of that feature was to decorate the schema with metadata @node and @edge so we could add metadata about the nature of the relations between types.

Metadata can also be used to customize generic types names as shown in section How to use a custom name on generic types?.

Deconstructing - Transforming - Rebuilding Queries

This feature allows your GraphQl server to deconstruct any GraphQl query as an AST that can then be filtered and modified based on your requirements. That AST can then be rebuilt as a valid GraphQL query. A great example of that feature in action is the graphql-authorize middleware for graphql-serverless which filters query's properties based on the user's rights.

For a concrete example, refer to the code below.

How To

How to use a custom name on generic types?

Use the special keyword @alias as follow:

const schema = `
  type Post {
    code: String
  }

  type Brand {
    id: ID!
    name: String
    posts: Page<Post>
  }

  @alias((T) => T + 's')
  type Page<T> {
    data: [T]
  }
  `

After transpilation, the resulting schema is:

const output = transpileSchema(schema)
// output:
// =======
// 	type Post {
// 		code: String
// 	}
// 
// 	type Brand {
// 		id: ID!
// 		name: String
// 		posts: Posts
// 	}
// 
// 	type Posts {
// 		data: [Post]
// 	}

Examples

WARNING: the following examples will be based on 'graphql-tools' from the Apollo team, but the string schema could also be used with the 'buildSchema' method from graphql.js

Type Inheritance

NOTE: The examples below only use 'type', but it would also work on 'input' and 'interface'

Before graphql-s2s

const schema = `
type Teacher {
	id: ID!
	creationDate: String

	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 

	title: String!
}

type Student {
	id: ID!
	creationDate: String

	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 

	nickname: String!
}`

After graphql-s2s

const schema = `
type Node {
	id: ID!
	creationDate: String
}

type Person inherits Node {
	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 
}

type Teacher inherits Person {
	title: String!
}

type Student inherits Person {
	nickname: String!
}`

Full code example

const { transpileSchema } = require('graphql-s2s').graphqls2s
const { makeExecutableSchema } = require('graphql-tools')
const { students, teachers } = require('./dummydata.json')

const schema = `
type Node {
	id: ID!
	creationDate: String
}

type Person inherits Node {
	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 
}

type Teacher inherits Person {
	title: String!
}

type Student inherits Person {
	nickname: String!
	questions: [Question]
}

type Question inherits Node {
	name: String!
	text: String!
}

type Query {
  # ### GET all users
  #
  students: [Student]

  # ### GET all teachers
  #
  teachers: [Teacher]
}
`

const resolver = {
        Query: {
            students(root, args, context) {
                return Promise.resolve(students)
            },

            teachers(root, args, context) {
                return Promise.resolve(teachers)
            }
        }
    }

const executableSchema = makeExecutableSchema({
  typeDefs: [transpileSchema(schema)],
  resolvers: resolver
})

Generic Types

NOTE: The examples below only use 'type', but it would also work on 'input'

Before graphql-s2s

const schema = `
type Teacher {
	id: ID!
	creationDate: String
	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 
	title: String!
}

type Student {
	id: ID!
	creationDate: String
	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 
	nickname: String!
	questions: Questions
}

type Question {
	id: ID!
	creationDate: String
	name: String!
	text: String!
}

type Teachers {
	data: [Teacher]
	cursor: ID
}

type Students {
	data: [Student]
	cursor: ID
}

type Questions {
	data: [Question]
	cursor: ID
}

type Query {
  # ### GET all users
  #
  students: Students

  # ### GET all teachers
  #
  teachers: Teachers
}
`

After graphql-s2s

const schema = `
type Paged<T> {
	data: [T]
	cursor: ID
}

type Node {
	id: ID!
	creationDate: String
}

type Person inherits Node {
	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 
}

type Teacher inherits Person {
	title: String!
}

type Student inherits Person {
	nickname: String!
	questions: Paged<Question>
}

type Question inherits Node {
	name: String!
	text: String!
}

input Filter<FilterFields> {
  field: FilterFields!,
  value: String!
}

enum TeachersFilterFields {
  firstName
  lastName
}

type Query {
  # ### GET all users
  #
  students: Paged<Student>

  # ### GET all teachers
  # You can use generic types on parameters, too.
  #
  teachers(filter: Filter<TeachersFilterFields>): Paged<Teacher>
}
`

This is very similar to C# or Java generic classes. What the transpiler will do is to simply recreate 3 types (one for Paged<Question>, Paged<Student> and Paged<Teacher>), and one input (Filter<TeachersFilterFields>). If we take the Paged<Question> example, the transpiled type will be:

type PagedQuestion {
	data: [Question]
	cursor: ID
}

Full code example

const { transpileSchema } = require('graphql-s2s').graphqls2s
const { makeExecutableSchema } = require('graphql-tools')
const { students, teachers } = require('./dummydata.json')

const schema = `
type Paged<T> {
	data: [T]
	cursor: ID
}

type Node {
	id: ID!
	creationDate: String
}

type Person inherits Node {
	firstname: String!
	middlename: String
	lastname: String!
	age: Int!
	gender: String 
}

type Teacher inherits Person {
	title: String!
}

type Student inherits Person {
	nickname: String!
	questions: Paged<Question>
}

type Question inherits Node {
	name: String!
	text: String!
}

type Query {
  # ### GET all users
  #
  students: Paged<Student>

  # ### GET all teachers
  #
  teachers: Paged<Teacher>
}
`

const resolver = {
        Query: {
            students(root, args, context) {
                return Promise.resolve({ data: students.map(s => ({ __proto__:s, questions: { data: s.questions, cursor: null }})), cursor: null })
            },

            teachers(root, args, context) {
                return Promise.resolve({ data: teachers, cursor: null });
            }
        }
    }

const executableSchema = makeExecutableSchema({
  typeDefs: [transpileSchema(schema)],
  resolvers: resolver
})

Metadata Decoration

Define your own custom metadata and decorate your GraphQL schema with new types of data. Let's imagine we want to explicitely add metadata about the type of relations between nodes, we could write something like this:

const { getSchemaAST } = require('graphql-s2s').graphqls2s
const schema = `
@node
type User {
	@edge('<-[CREATEDBY]-')
	posts: [Post]
}
`

const schemaObjects = getSchemaAST(schema);

// -> schemaObjects
//	{ 
//		"type": "TYPE", 
//		"name": "User", 
//		"metadata": { 
//			"name": "node", 
//			"body": "", 
//			"schemaType": "TYPE", 
//			"schemaName": "User", "parent": null 
//		}, 
//		"genericType": null, 
//		"blockProps": [{ 
//			"comments": "", 
//			"details": { 
//				"name": "posts", 
//				"metadata": { 
//					"name": "edge", 
//					"body": "(\'<-[CREATEDBY]-\')", 
//					"schemaType": "PROPERTY", 
//					"schemaName": "posts: [Post]", 
//					"parent": { 
//						"type": "TYPE", 
//						"name": "User", 
//						"metadata": { 
//							"type": "TYPE", 
//							"name": "node" 
//						} 
//					} 
//				}, 
//				"params": null, 
//				"result": { 
//					"originName": "[Post]", 
//					"isGen": false, 
//					"name": "[Post]" 
//				} 
//			}, 
//			"value": "posts: [Post]" 
//		}], 
//		"inherits": null, 
//		"implements": null 
//	}

Deconstructing - Transforming - Rebuilding Queries

This feature allows your GraphQl server to deconstruct any GraphQl query as an AST that can then be filtered and modified based on your requirements. That AST can then be rebuilt as a valid GraphQL query. A great example of that feature in action is the graphql-authorize middleware for graphql-serverless which filters query's properties based on the user's rights.

const { getQueryAST, buildQuery, getSchemaAST } = require('graphql-s2s').graphqls2s
const schema = `
	type Property {
		name: String
		@auth
		address: String
	}
	
	input InputWhere {
		name: String
		locations: [LocationInput]
	}
	
	input LocationInput {
		type: String 
		value: String
	}
	
	type Query {
		properties(where: InputWhere): [Property]

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