Nodejs Postgres Query with Call

Question

I'm trying to use the recommendation of the creator of node-postgres and separate the database call as a separate file. This will enable both scaling and consolidation of the various, boilerplate query types. Unfortunately, brianc's explanation of how to do this does not work for me. The "cb(err, result)" throws an error.

This is my test boilerplate database call (db.js):

            var pg = require('pg');
            var connectionString = 'postgres://postgres:password@10.10.10.10:5432/MyDatabase';
            var client = new pg.Client(connectionString, function(){
              if (err) {
                console.log(err);
                }
            });  
            var querytext = 'Select addr_type, addr_descr FROM ref_addr_type;';
            var result = [];
            var resultset = [];
            client.on('drain', client.end.bind(client));
            client.connect();

            module.exports = {
              query: function(callback) {

                var query = client.query(querytext, function(callback){

                  var resultsset = query.on('row', function(row, result) {
                    result.addRow(row);

                    query.on('end', function(res) {
                      client.end(function (err) {
                             if (err) throw err;

                             });    
                             console.log("JSON rows1: " + JSON.stringify(res));
                             return res; 
                    });
                    console.log("JSON rows2: " + JSON.stringify(result));   
                    return result;
                  });
                  console.log(resultset.length + ' rows were received');
                  callback = resultsset;
                  console.log("JSON3 rows: " + JSON.stringify(resultsset, null, ' '));
                  console.log("JSON4 rows: " + resultsset[0]);
                return callback;        
                })
              }
            }

This is the script calling it (call.js):

var db = require('../db');
var items = [];

items = db.query();

console.log("Main db: " + items);
console.log("Main db json: " + JSON.stringify(items));
console.log("Main db inspect: " + util.inspect(items));;

This is the console output:

0 rows were received
JSON3 rows: {
 "text": "Select addr_type, addr_descr FROM ref_addr_type;",
 "portal": "",
 "_result": {
  "command": "SELECT",
  "rowCount": 5,
  "oid": null,
  "rows": [
   {
    "addr_type": "2",
    "addr_descr": "Home"
   },
   {
    "addr_type": "3",
    "addr_descr": "Institution"
   },
   {
    "addr_type": "1",
    "addr_descr": "Company"
   },
   {
    "addr_type": "8",
    "addr_descr": "Organization"
   },
   {
    "addr_type": "10",
    "addr_descr": "Government"
   }
  ],
  "fields": [
   {
    "name": "addr_type",
    "tableID": 17549,
    "columnID": 1,
    "dataTypeID": 20,
    "dataTypeSize": 8,
    "dataTypeModifier": -1,
    "format": "text"
   },
   {
    "name": "addr_descr",
    "tableID": 17549,
    "columnID": 2,
    "dataTypeID": 1043,
    "dataTypeSize": -1,
    "dataTypeModifier": -1,
    "format": "text"
   }
  ],
  "_parsers": [
   null,
   null
  ],
  "rowAsArray": false
 },
 "isPreparedStatement": false,
 "_canceledDueToError": false,
 "_promise": null,
 "domain": null,
 "_events": {},
 "_eventsCount": 1
}
JSON4 rows: undefined

As you can see, there is no console.log output within call.js ("Main db:, Main db json:" and "Main db inspect:"). Also, no rows are counted in "resultset" and I can't get any results from the JSON4 array.

I've spent 4 days on this and am probably making a bunch of rookie mistakes. Please provide some guidance on getting the db.js to deliver the values to call.js.

Setting that "end" event handler *inside* the "row" event handler seems like a bad idea. — Pointy, Feb 09 '17 at 03:35
Bad design. Any failure in connection, and your code will die. Only the use of the pool enables automatic re-connection. — vitaly-t, Feb 09 '17 at 08:08
Where should the "end" event handler go? That arrangement seemed to be the most appropriate way of shutting down the connection when the query was complete. Nonetheless, that's probably not relevant to passing the values back to call.js. Vitaly, I'll consider pool as soon as I get this working. My connection works, but the problem is upstream. BTW, I just started learning javascript this month. — jurban1997, Feb 09 '17 at 17:41
@jurban1997 this is a much better start: http://stackoverflow.com/questions/42122441/closing-postgres-pg-client-connection-in-node-js — vitaly-t, Feb 09 '17 at 19:57

Nodejs Postgres Query with Call

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