error handle in promise nodejs + postgresql

Question

I just start learning nodejs below is my code ...
Q1. Do I handle the error message correct way with insertUserPendingBase()??
I check the return message if equal success or not. And if so what is the then can do in this example?

Q2. I use pg when I do execute the query do I need to do anything for prevent SQL injection? I saw in document there's no need, but I'm not sure..

any suggestions can improve my code will be welcome

routes

var express = require('express');
var router = express.Router();
var co = require('co');

// .. post
var insertUserPendingBase = function(token) {
  return new Promise(function (fulfill, reject){
    var query = "INSERT INTO user_pending_base (user_pending_email,user_pending_password,token_timestamp,token) VALUES ('" + user_email + "','" + user_password + "', CURRENT_TIMESTAMP,'" + token + "')";
    dbClient.query(query, function(err, result) {
      if (err) {
        reject(err);
      } else {
        fulfill('success');
      }
    });
  });

  // .then(function(value) {
  //   console.log(value);
  //   throw "error message";
  // }).catch(function(e) {
  //   console.log(e);
  // });
}

co(function *() {
  // ...
  var insertUserPendingBaseResult = yield insertUserPendingBase(generateTokenResult);

  console.log('insertUserPendingBaseResult:'+insertUserPendingBaseResult);
  if (insertUserPendingBaseResult == 'success') { // handle error like this ??

  }

  res.render('Account/Register/Index', {
    partials: {
      Content: 'Account/Register/Content',
    }
  });
}).catch(onerror);

function onerror(err) {
  console.error(err.stack);
}

Update

If I change fulfill(result) instead of fulfill('success') I will get below object but there's no message about fail or success

{ command: 'INSERT',
  rowCount: 1,
  oid: 0,
  rows: [],
  fields: [],
  _parsers: [],
  RowCtor: null,
  rowAsArray: false,
  _getTypeParser: [Function] }

Update 2

I find a way use try and catch inside co(function *() like below, but I'm not sure is this the best way make a clean code ?

co(function *() {
... 
try {
  var insertUserPendingBaseResult = yield insertUserPendingBase(generateTokenResult);
  // if success ...

} catch (err) {
  // if fail
  console.log(err);
}

If you want to use node-postgres via promises, check out pg-promise. — vitaly-t
– vitaly-t, Commented Aug 24, 2015 at 18:31

krl · Accepted Answer · 2015-08-01 19:58:21Z

1

Cannot comment on SQL injection, but fulfill('success') must be fulfill(result).

To handle success and failure of the promise you should use then and catch, no need for generators:

insertUserPendingBase.then(function(result) { /* handle result here */ })
                     .catch(function(ex) { /* handle exception here */ })

answered Aug 1, 2015 at 19:58

krl

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3 Comments

user1775888 Over a year ago

Thanks for reply and the example code let me understand how to use then and catch ! I'm just paste a part of my code , I need to crud other tables depends first table return result. So I don't want too many callback inside then .

user1775888 Over a year ago

If I use generators should I return result like fulfill(result) instead fulfill('success') ? and how to catch the error after execute?

krl Over a year ago

fulfill(result), but I don't see why you want to use generators. In many ways they are just a stepping stone toward ES7 async / await which you can already have today with babel.

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