javascript - Error handling and status codes with knex in koa -

i'm experimenting koa , knex build restful web service, , while got basics working i'm stuck @ handling errors. i'm using koa-knex-middleware wraps knex in generator.

i have following code defines happens , post requests particular resource:

var koa = require('koa'); var koabody = require('koa-body')(); var router = require('koa-router')(); var app = koa();  var knex = require('./koa-knex');  app.use(knex({     client: 'sqlite3',     connection: {         filename: "./src/server/devdb.sqlite"     } }));  router     .get('/equipment', function *(next){         this.body = yield this.knex('equipment');     })     .post('/equipment', koabody, function *(next){         this.body = yield this.knex('equipment').insert(this.request.body)     });  app.use(router.routes()).use(router.allowedmethods());  app.listen(4000); 

this works in general, can't manage change http status codes. example, want return 201 post requests added item 400 malformed requests don't fit db schema.

i tried using tap() , catch() knex, wasn't able modify status code.

    this.body = yield this.knex('equipment').insert(this.request.body).tap(function(){this.response = 204}.bind(this)) 

just hangs forever. same if try use .catch set 400.

reading on koa @ first thought understood how supposed work, i'm not sure anymore. interaction of koa generators , promises knex confusing me.

is general approach sound, or mixing knex , koa way bad idea? , how handle errors , status codes combination?

you should able use standard try{}catch(err){} block.

https://github.com/tj/co#examples

vrouter     .get('/equipment', function *(next){         this.body = yield this.knex('equipment');     })     .post('/equipment', koabody, function *(next){         try{           this.body = yield this.knex('equipment').insert(this.request.body)           this.status = 201;         }         catch(err){           this.throw(400, 'malformed request...');           // or           // this.status = 400;         }      });