最近在看 koa，用 koa+mysql 搭了个简单 demo 环境后准备试一下，然后就一直返回 Not Found，把数据库相关操作注释掉之后又好了，最后发现原因是 logger 中间件里的next()前没加return 。[喷水]
Code
const Koa = require('koa');
const route = require('koa-route');
const cors = require('koa2-cors');
const knex = require('knex');
const app = new Koa();
const mysql = knex({
client: 'mysql',
connection: {
host: 'localhost',
user: 'root',
password: '***',
database: 'test'
},
debug: true,
pool: {
min: 0,
max: 7
},
acquireConnectionTimeout: 10000,
migrations: {
tableName: 'migrations'
}
});
const getCodeById = id => mysql.select().table('test').where('a_tid', id);
const logger = (ctx, next) => {
console.log(`${new Date().toLocaleString()} ${ctx.request.method} ${ctx.request.url}`);
return next(); // **前边要加 return**
}
const test = async ctx => {
let res = {};
try {
res.data = await getCodeById(1);
res.status = 1;
res.msg = 'SUCCESS';
} catch (error) {
console.log('error: ', error);
res.data = [];
res.status = 0;
res.msg = 'FAIL';
}
ctx.response.body = res;
};
app.use(cors());
app.use(logger);
app.use(route.get('/test', test));
app.listen(3000);后来发现已经有现成的 koa-logger 了 [#允悲]wwww
Answers from stackoverflow
It seems that if you want to use a common function as middleware, you have to return the next function.
Why common function as middlerware have to return the next function
I think it’s because you have to return a promise from your middleware to work with other middlewares. The next return a promise, as you return it, you return a promise. See this issue for more discussions github.com/koajs/koa/issues/997.