What could be the problem when using koa-mysql?

Question

Node.js

Good day.
I am writing (or rather rewriting with Express) an application in Koa. I use the Mysql database and the koa-mysql module ( https://github.com/eladnava/koa-mysql). And there was a problem with the following design:

exports.get=function* (next){
  const ctx=this;
  let sql = "SELECT * FROM clients_forums_knowledge_base ORDER BY orders ASC";
  let forumsKnowledgeBase = yield ctx.locals.db.query(sql);
  forumsKnowledgeBase.forEach((elem,idx) => {
    let sql='SELECT clients_knowledge_base.name, clients_knowledge_base.id,clients_knowledge_base.file FROM clients_knowledge_base,clients_forums_knowledge_base WHERE clients_forums_knowledge_base.id = clients_knowledge_base.forum AND clients_knowledge_base.forum = ? ORDER BY name ASC';
    let rows = yield ctx.locals.db.query(sql,elem.id);
    elem.items=rows ;
  })
};

On startup, an error occurs:

app-0 /var/www/app/routes/clients/knowledgebase.js:10
app-0             let rows = yield ctx.locals.db.query(sql,elem.id);
app-0                              ^^^
app-0 SyntaxError: Unexpected identifier
app-0     at exports.runInThisContext (vm.js:53:16)
app-0     at Module._compile (module.js:511:25)
app-0     at Object.Module._extensions..js (module.js:550:10)
app-0     at Module.load (module.js:456:32)
app-0     at tryModuleLoad (module.js:415:12)
app-0     at Function.Module._load (module.js:407:3)
app-0     at Function._load (/usr/lib/node_modules/pm2/node_modules/pmx/lib/transaction.js:62:21)
app-0     at Module.require (module.js:466:17)
app-0     at require (internal/module.js:20:19)
app-0     at Object.<anonymous> (/var/www/app/routes/index.js:6:43)

Just in case app.js:

const koa = require('koa');
const http = require('http');
const path = require('path');
const config = require('./config');
const favicon = require('koa-favicon');
const logger = require('koa-logger');
const locals = require('koa-locals');
const serve = require('koa-static');
const body = require('koa-better-body');
const session = require('koa-generic-session');
const mysql = require('koa-mysql');
const sessionStore=("./sessionStore");
const Pug = require('koa-pug');
const locale = require('koa-locale');
const i18n = require('koa-i18n');
const router = require('./routes');
const app = koa();
locals(app, {
  db: mysql.createPool(config.get('db'))
});

locale(app)
app.keys = ['KillerIsJim']
app	
  .use(favicon(__dirname + '/public/favicon.ico'))
  .use(logger())
  .use(body())
  .use(session({store: sessionStore}))
  .use(router.routes())
  .use(router.allowedMethods())
  .use(serve(__dirname + '/public'))
  
router.use(i18n(app, {directory: './config/locales',locales: ['en','ru-RU'],modes: ['header']}))

const pug = new Pug({viewPath: __dirname + '/views',noCache:true,app: app})
const io=require('./lib/socket');
io.attach(app)
app.listen(config.get('port'))

And routes/index.js

const router = require('koa-router')();
const koaBody = require('koa-body')()
router.redirect('/','/knowledgebase');
router.get('/knowledgebase',require('./clients/knowledgebase').get);
module.exports = router;

Can anyone suggest what could be the problem?

Answer 1

yield can only be used in a generator, in your nested function
it is easiest to replace forEach with a regular loop:

exports.get=function* (next){
  const ctx=this;
  let sql = "SELECT * FROM clients_forums_knowledge_base ORDER BY orders ASC";
  let forumsKnowledgeBase = yield ctx.locals.db.query(sql);
  for(let idx = 0, n = forumsKnowledgeBase.length; idx < n; idx++) {
    let elem = forumsKnowledgeBase[idx];
    let sql='SELECT clients_knowledge_base.name, clients_knowledge_base.id,clients_knowledge_base.file FROM clients_knowledge_base,clients_forums_knowledge_base WHERE clients_forums_knowledge_base.id = clients_knowledge_base.forum AND clients_knowledge_base.forum = ? ORDER BY name ASC';
    let rows = yield ctx.locals.db.query(sql,elem.id);
    elem.items=rows ;
  }
};