example-custom.js

/**
 * Created by wenshao on 2018/2/10.
 */
'use strict';
const Koa = require('koa');
const Body = require('koa-bodyparser');
const router = require('koa-router')();
const {
    GraphQLObjectType,
    GraphQLSchema,
    GraphQLString,
    GraphQLInt
} = require('graphql');

/**
 * 自定义异常类
 */
class RequestException extends Error{
    constructor() {
        super();
        this.name = "RequestException";
        this.code = null;
        this.message = null;
        this.serverName = null;
        this.methodName = null;
        this.fullMessage = null;
    }
}


const reIpv4 = '.*:.*:.*:(.*)';
/**
 * 中间件
 * 1 自定义context 可以传入ctx对象
 * 2 增加resolve执行的信息
 * 3 自定义日志输出
 * 4 错误处理统一处理
 * @param options
 * @return {function(*=, *)}
 */
function graphqlKoaLog(options) {
    const {graphqlKoa} = require('apollo-server-koa');
    const logger = options.log && 'info' in options.log ? options.log : console;
    return async (ctx, next) => {
        await graphqlKoa({
            schema: options.schema,
            context: {  // 传入ctx  也可以增加其他值  如用户信息等
                ctx: ctx,
            },
            tracing: true,
            formatError(error){
                if (typeof error === 'object') {
                    if (typeof error.originalError === 'object'
                        &&
                        error.originalError.name === 'RequestException' ) { // 自定义的请求异常 则进行拦截
                        error.message = 'thrift error';     // 返回到前端message
                        return error;
                    }
                }
                return error;
            },
            formatResponse(data, all) { // data 为返回到前端的全部数据  all为执行resolve相关的信息 类似ctx
                let ipv4 = ctx.ip.match(reIpv4);
                if (ipv4 instanceof Array && ipv4.length === 2) ipv4 = ipv4[1];
                else if (ipv4 === null) ipv4 = ctx.ip;
                else ctx.ipv4 = ipv4;   // 找到ip
                if (ctx.method !== 'OPTIONS') logger.info(ipv4, `${data.extensions.tracing.duration / 1000}ms`,
                    '\n============query=======\n',all.query, '\n============variables=======\n', all.variables);
                delete data.extensions; // 前端不需要 则删除
                return data;
            }
        })(ctx);
    }
}


const User = new GraphQLObjectType({
    name: 'User',
    description: 'User对象',
    fields: {
        id: {
            type: GraphQLInt
        },
        name: {
            type: GraphQLString
        },
    }
});

const Query = new GraphQLObjectType({
    name: 'Query',
    fields: {
        user: {
            type: User,
            args: {
                id: {
                    type: GraphQLInt
                }
            },
            resolve: function (root, args, context) {
                const re = new RequestException();
                re.code = 1;
                re.message = '查询失败';
                throw re;
            }
        }
    }
});
const myGraphQLSchema = new GraphQLSchema({
    query: Query
});
const app = new Koa();
const PORT = 3000;

// Body is needed just for POST.
app.use(Body());

router.post('/graphql', graphqlKoaLog({
    schema: myGraphQLSchema,
}));
router.get('/graphql', graphqlKoaLog({
    schema: myGraphQLSchema
}));
app.use(router.routes());
app.use(router.allowedMethods());
app.listen(PORT);