server-component.js

class AppComponent {

    beforeRegister() {
        this.is = 'server-component';
    }

    ready() {
        const bodyParser = require('body-parser');
        const logger = require('morgan');

        this.bodyParserMW = bodyParser.json();
        this.bodyParserURLEncodedMW = bodyParser.urlencoded({extended: true});
        this.loggerMW = logger('dev');

        this.paramCallback = (app) => {
            app.param('collectionName', function(req, res, next, collectionName){
//                req.collection = db.collection(collectionName)
                return next()
            });
        };

        this.getIndex = (req, res) => {
            res.send('please select a collection, e.g., /collections/messages');
        };

        this.getCollection = (req, res, next) => {
            req.collection.find({} ,{limit: 10, sort: {'_id': -1}}).toArray(function(e, results){
              if (e) return next(e)
              res.send(results)
          });
        }

        this.postCollection = (req, res, next) => {
            req.collection.insert(req.body, {}, function(e, results){
              if (e) return next(e)
              res.send(results)
          });
        }

        this.getCollectionEntity = (req, res, next) => {
            req.collection.findById(req.params.id, function(e, result){
              if (e) return next(e)
              res.send(result)
          });
        }

        this.putCollectionEntity = (req, res, next) => {
            req.collection.updateById(req.params.id, {$set: req.body}, {safe: true, multi: false}, function(e, result){
              if (e) return next(e)
              res.send((result === 1) ? {msg:'success'} : {msg: 'error'})
          });
        }

        this.deleteCollectionEntity = (req, res, next) => {
            req.collection.removeById(req.params.id, function(e, result){
              if (e) return next(e)
              res.send((result === 1)?{msg: 'success'} : {msg: 'error'})
          });
        }
    }
}

Polymer(AppComponent);