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_sidebar.md

@@ -39,6 +39,7 @@
   - DB
     - [MySQL](basic/db/mysql.md)
     - [Redis](basic/db/redis.md)
+    - [GraphQL](basic/db/graphql.md)
   - 常用框架
     - [HAPI](basic/framework/hapi.md)
     - [Socket.IO](basic/framework/socketio.md)

basic/db/graphql.md

@@ -0,0 +1,213 @@
+# GraphQL
+
+# 安装
+
+准备工作:
+
+- 数据库环境(MySQL, MongoDB)
+- Node.js (版本大于 v7.6.0) 
+
+本章节示例项目源码位于: <https://github.com/willin/start-grahql-server>
+
+安装各类依赖,养成良好习惯,第一步从`eslint`起.
+
+!> 另外, 不建议安装`Babel`来转译服务器端的代码,因为最新的 Node.js 版本已经支持了很多 ES7 的新特性.
+
+# 定义结构(Schema)
+
+graphql-tools 定义结构(Schema): <http://dev.apollodata.com/tools/graphql-tools/generate-schema.html>
+
+使用 graphql-tools 自动生成结构:
+
+```js
+const typeDefs = `
+type Author {
+  id: Int
+  firstName: String
+  lastName: String
+  posts: [Post]
+}
+type Post {
+  id: Int
+  title: String
+  text: String
+  views: Int
+  author: Author
+}
+type Query {
+ author(firstName: String, lastName: String): Author
+ post(title: String): Post
+ getFortuneCookie: String
+}
+schema {
+ query: Query
+}
+`;
+```
+
+## Schema 扩展阅读 
+
+如果不使用该工具自动生成, 而是想要自己定义完整的数据结构, 可以参考: <https://graphql.js.cool/learn/schema/>
+
+也可以在后面进阶的章节中了解: [MySQL 向 GraphQL 迁移](/#/experience/advanced/mysql-graphql)
+
+# 快速搭建原型服务器(Mocked Server)
+
+graphql-serve: <https://github.com/apollographql/graphql-server>
+
+本文中分别使用 `express` 和 `koa` 做了两个服务器.
+
+```js
+// express
+const express = require('express');
+const { graphqlExpress, graphiqlExpress } = require('graphql-server-express');
+const bodyParser = require('body-parser');
+const schema = require('./schema');
+
+const GRAPHQL_PORT = 3000;
+
+const graphQLServer = express();
+
+graphQLServer.use('/graphql', bodyParser.json(), graphqlExpress({ schema }));
+graphQLServer.use('/graphiql', graphiqlExpress({ endpointURL: '/graphql' }));
+
+graphQLServer.listen(GRAPHQL_PORT, () => console.log(
+  `GraphQL Server is now running on http://localhost:${GRAPHQL_PORT}/graphql`
+));
+```
+
+```js
+// koa
+const Koa = require('koa');
+const KoaRouter = require('koa-router');
+const koaBody = require('koa-bodyparser');
+const { graphqlKoa, graphiqlKoa } = require('graphql-server-koa');
+const schema = require('./schema');
+
+const app = new Koa();
+const router = new KoaRouter();
+const PORT = 3000;
+
+// koaBody is needed just for POST.
+app.use(koaBody());
+
+router.post('/graphql', graphqlKoa({ schema }));
+router.get('/graphql', graphqlKoa({ schema }));
+router.post('/graphiql', graphiqlKoa({ schema }));
+router.get('/graphiql', graphiqlKoa({ schema }));
+
+app.use(router.routes());
+app.use(router.allowedMethods());
+app.listen(PORT);
+```
+
+!> 注意: 本来是想用`koa`做的, 但在本文更新的时候, `graphql-server-koa` 有 Bug, 跑起来之后会报错 `NO SCHEMA AVAILABLE`, 所以又写了一个 `express` 的 Server, 可运行.
+
+# 连接 SQL 数据库
+
+使用 `sequelize`
+
+```js
+const db = new Sequelize('blog', 'root', 'root', {
+  dialect: 'mysql',
+  host: 'localhost'
+});
+
+const AuthorModel = db.define('author', {
+  firstName: { type: Sequelize.STRING },
+  lastName: { type: Sequelize.STRING }
+});
+
+const PostModel = db.define('post', {
+  title: { type: Sequelize.STRING },
+  text: { type: Sequelize.STRING }
+});
+
+AuthorModel.hasMany(PostModel);
+PostModel.belongsTo(AuthorModel);
+
+// create mock data with a seed, so we always get the same
+casual.seed(123);
+db.sync({ force: true }).then(() => {
+  _.times(10, () => AuthorModel.create({
+    firstName: casual.first_name,
+    lastName: casual.last_name
+  }).then(author => author.createPost({
+    title: `A post by ${author.firstName}`,
+    text: casual.sentences(3)
+  })));
+});
+
+const Author = db.models.author;
+const Post = db.models.post;
+```
+
+# 连接 MongoDB
+
+使用 `mongoose`
+
+```js
+// somewhere in the middle:
+Mongoose.connect('mongodb://localhost/views');
+
+const ViewSchema = Mongoose.Schema({
+  postId: Number,
+  views: Number
+});
+
+const View = Mongoose.model('views', ViewSchema);
+```
+
+# 从 GraphQL 中使用 REST 服务
+
+```js
+const FortuneCookie = {
+  getOne() {
+    return fetch('http://fortunecookieapi.herokuapp.com/v1/cookie')
+      .then(res => res.json())
+      .then(res => res[0].fortune.message);
+  }
+};
+```
+
+
+# 编写解决器(Resolver)
+
+![graphql](https://user-images.githubusercontent.com/1890238/28000944-9c4c3f32-64ee-11e7-902e-cbf3a01d90e2.png)
+
+GraphQL后边可以连接各种持久化存储,甚至RESTful远程资源.
+
+```js
+const { Author, View, FortuneCookie } = require('./connectors');
+
+const resolvers = {
+  Query: {
+    author(_, args) {
+      // MySQL
+      return Author.find({ where: args });
+    },
+    getFortuneCookie() {
+      // 远程REST服务
+      return FortuneCookie.getOne();
+    }
+  },
+  Author: {
+    posts(author) {
+      return author.getPosts();
+    }
+  },
+  Post: {
+    author(post) {
+      return post.getAuthor();
+    },
+    views(post) {
+      // MongoDB
+      return View.findOne({ postId: post.id })
+        .then(view => view.views);
+    }
+  }
+};
+
+module.exports = resolvers;
+```
+