how to use koa.js+mongoose 如何使用？

app.js

var koa = require('koa')
  , mongoose = require('mongoose')
  , Blog = require('./models/blog')
  ;

//连接数据库
var uris = 'mongodb://192.168.1.2/db,mongodb://192.168.1.3/db';
var options = {
      db: { native_parser: true },
      server: {'auto_reconnect': true,'poolSize': 10},
      replset: {readPreference: 'nearest',strategy: 'ping',rs_name: 'myReplSet'},
    };
mongoose.connect(uris,options);

//路由
app.get('/', function *(){
  var blogs = yield Blog.find().exec();
  yield this.render('blog', {blogs: blogs});
})
app.listen(8317);

blog.js

'use strict';

var mongoose = require('mongoose'),
    Schema = mongoose.Schema;

var BlogSchema = new Schema({
  title:{
    type:String,
    required: '标题为空！'
  }
});

BlogSchema.set('toJSON', {
  getters: true,
  virtuals: true,
  transform: function(doc, ret, options) {
    options.hide = options.hide || '_id __v';
    if (options.hide) {
      options.hide.split(' ').forEach(function (prop) {
        delete ret[prop];
      });
    }
  }
});

module.exports = mongoose.model('Blog', BlogSchema);