从零编写一个Koa-graphQL的案例

在 Nest.js 的文档中看到了有集成 GraphQL 的指导，所以在本地尝试下先用 Koa 写出一个 DEMO，之后再去与 Nest.js 集成起来。

先写出数据库模型（这个文件是之前就存在的，没有做更改，将文件名改成了 models.ts）：

/**
 * Created by w on 2018/4/13.
 */
const mongoose = require('mongoose');

mongoose.Promise = global.Promise;
mongoose.connect('mongodb://localhost/ticket', {
  server: {
    socketOptions: {keepAlive: 1}
  }
});

const models = {
  users: {
    username: {
      type: String,
      required: true
    },
    password: {
      type: String,
      required: true
    },
    description: {type: String},
    createTime: {
      type: Date,
      default: new Date()}
  },
  tickets: {
    name: {
      type: String,
      required: true
    },
    price: {
      type: Number,
      requred: true
    },
    holdTime: {   // 举办时间
      type: Date,
      required: true
    },
    count: {    // 剩余数量
      type: String,
      required: true
    },
    place:{
      type: String,
      required: true
    },
    img: {type: String},
    description: {type: String},
    publicTime: {
      type: Date,
      default: new Date()},
  }
};

for (let m in models) {mongoose.model(m, mongoose.Schema(models[m]));
}

module.exports = {getModules: (name) => {return mongoose.model(name);
  }
};

之后编写各自模型的 GraphQL 查询文件（user.ts)）：

// @ts-ignore
const {
  //@ts-ignore
  graphql, GraphQLSchema, GraphQLObjectType,GraphQLString,GraphQLID,GraphQLList,GraphQLNonNull,GraphQLInt,isOutputType,
} = require('graphql');
// @ts-ignore
const User = require('../db/model').getModules('users');

const userType = new GraphQLObjectType({
  name: 'User',
  fields: {
    username: {type: GraphQLString,},
    password: {type: GraphQLString,},
    description: {type: GraphQLString,},
    createTime: {type: GraphQLString,}
  }
});

module.exports = {
  query: {type: new GraphQLList(userType),
    args: {
      username: {
        username: 'username',
        type: GraphQLNonNull(GraphQLString)
      }
    },
    resolve(root, params, options) {if (params.username === '$all') {return User.find().exec()}
      return User.find({username: params.username}).exec();}
  },
  create: {type: new GraphQLList(userType),
    args: {
      username: {
        username: 'username',
        type: GraphQLNonNull(GraphQLString)
      },
      possword: {
        name: 'price',
        type: GraphQLNonNull(GraphQLString)
      },
      createTime: {type: GraphQLString,},
      description: {
        name: 'description',
        type: GraphQLString
      }
    },
    resolve: async (root, params, options) => {
      let user = new User({
        username: params.username,
        password: params.password,
        description: params.description,
        createTime: params.createTime
      });
      try {await user.save();

        return user.find({username: params.username}).exec()}catch(e) {console.error("Error while save data:", e);
      }
    }
  }
}

ticket.ts:

// @ts-ignore
const {
  // @ts-ignore
  graphql, GraphQLSchema, GraphQLObjectType, GraphQLString, GraphQLID, GraphQLList, GraphQLNonNull, GraphQLInt, isOutputType,
} = require('graphql');
// @ts-ignore
const Ticket = require('../db/model').getModules('tickets');

const ticketType = new GraphQLObjectType({
  name: 'Ticket',
  fields: {
    name: {type: GraphQLString},
    price: {type: GraphQLInt},
    holdTime: {type: GraphQLString},
    count: {type: GraphQLInt},
    place: {type: GraphQLString},
    img: {type: GraphQLString},
    description: {type: GraphQLString},
    publicTime: {type: GraphQLString}
  }
});

module.exports = {
  query: {type: new GraphQLList(ticketType),
    args: {
      name: {
        name: 'name',
        type: GraphQLNonNull(GraphQLString)
      }
    },
    resolve(root, params, options) {if (params.name === '$all') {return Ticket.find().exec()}
      return Ticket.find({name: params.name}).exec();}
  },
  create: {type: new GraphQLList(ticketType),
    args: {
      name: {
        name: 'name',
        type: GraphQLNonNull(GraphQLString)
      },
      price: {
        name: 'price',
        type: GraphQLInt
      },
      holdTime: {
        name: 'holdTime',
        type: GraphQLNonNull(GraphQLString)
      },
      count: {
        name: 'count',
        type: GraphQLNonNull(GraphQLInt)
      },
      place: {
        name: 'place',
        type: GraphQLNonNull(GraphQLString)
      },
      img: {
        name: 'img',
        type: GraphQLString
      },
      description: {
        name: 'description',
        type: GraphQLString
      },
      publicTime: {
        name: 'publicTime',
        type: GraphQLString
      }
    },
    resolve: async (root, params, options) => {
      let ticket = new Ticket({
        name: params.name,
        price: params.price,
        holdTime: params.holdTime,
        count: params.count,
        place: params.place,
        img: params.img,
        description: params.description,
        publicTime: params.publicTime
      });
      try {await ticket.save();

        return Ticket.find({name: params.name}).exec()}catch(e) {console.error("Error while save data:", e);
      }
    }
  }
}

接下来编写用于查询或修改数据的 Schema.ts:

const {
  //@ts-ignore
  GraphQLSchema, GraphQLObjectType,
} = require('graphql');
//@ts-ignore
const Ticket = require('./ticket');
//@ts-ignore
const User = require('./user');

module.exports = new GraphQLSchema({
  query: new GraphQLObjectType({
    name: 'Queries',
    fields: {
      Ticket: Ticket.query,
      User: User.query,
    }
  }),
  mutation: new GraphQLObjectType({
    name: 'Mutations',
    fields: {
      Ticket: Ticket.create,
      User: User.create,
    }
  })
})

编写服务端 (server.ts)：

const Koa = require('koa');
const app = new Koa();
const koaBody = require('koa-body');
const CombileRouter = require('./combineRouter');

app
  .use(koaBody({
    multipart: true,
    formidable: {keepExtensions: true,},
  }))
  .use(CombileRouter.routes())
  .use(CombileRouter.routes());

app.listen(5000, () => {console.log('App running~');
})

定义 ticket 路由的 ticket.router.ts:

const KoaRouter = require('koa-router');
const ticketRouter = new KoaRouter();
// @ts-ignore
const {graphqlKoa, graphiqlKoa} = require('graphql-server-koa');
// @ts-ignore
const Ticket = require('../db/model').getModules('tickets');
const ticketSchema = require('../graphql/schema');

ticketRouter.get('/ticket/all', async (ctx) => {
  try {let result = await Ticket.find({});

    ctx.body = {data: Object.assign({}, result), code: '0' };
  } catch (e) {console.error("Getting all ticket error:", e);
  }
});

ticketRouter.post('/graphql', async (ctx, next) => {console.log('graphql', ctx.request.body);
  await graphqlKoa({schema: ticketSchema})(ctx, next)
})
.get('/graphql', async (ctx, next) => {await graphqlKoa({schema: ticketSchema})(ctx, next)
})
.get('/graphiql', async (ctx, next) => {await graphiqlKoa({endpointURL: '/graphql'})(ctx, next)
})


module.exports = ticketRouter;

还有之前定义的 user.router.ts(测试这个 user 路由是否是 reachable 的):

const Router = require('koa-router');
const userRouter = new Router();
// @ts-ignore
const {graphiqlKoa} = require('graphql-server-koa');

userRouter.get('/user/all', async (ctx) => {
  ctx.body = {
    code: '0',
    msg: 'OK',
    info: {
      data: [{
        username: 'a',
        id: 0,
        desc: 'ok',
      }, {
        username: 'd',
        id: 1,
        desc: 'ok',
      }, {
        username: 'c',
        id: 2,
        desc: 'ok',
      }, {
        username: 'b',
        id: 3,
        desc: 'ok',
      }]
    }
  }
});

module.exports = userRouter;

将两个路由文件融合起来 (combineRouter.ts):

const UserRouter:object = require('./koa-router/user.router');
const TicketRouter:object = require('./koa-router/ticket.router');

const combiler = (routers: object[]): object => {let arr = [];
  
  routers.forEach(v => {
    //@ts-ignore
    arr.push(...v.stack)
  });
  return Object.assign(routers[0], {stack:arr});
}

const res = combiler([UserRouter, TicketRouter]);

module.exports = res;

OK 了，这部分就写好了基础的 query 和 mutation 功能，还有删除的功能之后再加上。
附上 tsconfig.json 文件：

{
  "compilerOptions": {
    "module": "commonjs",
    "target": "es6",
    "sourceMap": true,
    "experimentalDecorators": true,
  },
  "exclude": ["node_modules"]
}