node.js - Bluebird promisify on function with return value -

i'd use bluebird's promisify function on aws putitem function. notice docs returns aws.request object. not interested in object , ideally call db.putitem({...}); , promise back. possible? when tried it, promisify'd function still returns aws.request object, suppose reasonable, it's not want in case.

for time being creating promise object , manually mapping success , error data resolve/reject promise functions, feels i'm writing unnecessary boilerplate code, since aside return value, putitem function (and may of other functions) seems suited promisify.

as requested, here relevant parts of code:

//datastore.js

var aws = require('aws-sdk');  var shareddb;  if (!shareddb) {     aws.config.update({accesskeyid: 'akid', secretaccesskey: 'secret', region: "us-west-2"});     shareddb = new aws.dynamodb();     shareddb.setendpoint("http://localhost:8000");     promise.promisify(shareddb.putitem);  }  module.exports.shareddb = shareddb; 

//user.js

var db = require('../datastore/dynamodbconnection').shareddb; var promise = require("bluebird");   function user() { var user = this; ...  user.save = function () {         var params = {             item: {                 username: {s: 'test'},                 passwordhash: {s: 'test'}             },             tablename: 'users',             expected: {                 username: {exists: false}             }         };         return db.putitem(params); //this have promise returned.  instead aws.request object. } ... } 

update

you're using promisify wrong, returns promisified function.

var putitemasync = promise.promisify(shareddb.putitem);  

and use putitemasync. also, should call promisify once , cache it.

---

putitem takes callback, resolves stream, promisifying little tricker usual.

return new promise(function(resolve,reject){     dynamodb.putitem(     {"tablename":"table1",         "item":{             "color":{"s":"white"},             "name":{"s":"fancy vase"},             "weight":{"n":"2"}         }     }, function(result) {         var wholeresult = [];         result.on('data', function(chunk){             wholeresult.push(chunk);         });         result.on('end', function(){ resolve(buffer.concat(wholeresult))});         result.on('error', function(e){ reject(new error(e)); });     }); });