How to i fetch value of client.query in Node JS with PG?

Question

I am using node.js and make database connection with postgresql. My dbConfig.js look like :-

var pg = require('pg');
var client  = new pg.Client({
    host:'myhoost',
    port:'5432',
    user:'myuser',
    password:'mypass',
    database:'mydb',
    ssl:true
});
client.connect();
module.exports.myconnection = client;

my api.js file look like :-

var dbConnect = require('./dbConfig.js');
var client = dbConnect.myconnection;
var ser = function(value) {
    var query = "SELECT * FROM tbl_api WHERE apikey = '" + value + "'";

    client.query(query, function(err, result) {
        var res = true;
        if (err) {
            var res = false;
        } else {
            if (result.rowCount > 0) {
                res = true;
            } else {
                res = false;
            }
        }
       return res;
    });
};
module.exports.checkAPI = ser;

my api.js look like:-

var express = require('express');
var app = express();
var apiCheck = require('./api.js');


//APIKey Generator check api
app.get('/apicheck/:apikey', function(request, response) {
    var value = request.params.apikey;
    var result = apiCheck.checkAPI(value);
    response.send(result);
});

i want the res from client.query into the result variable. I found one same issue with mysqljs issue but still i am not able to solve this doubt.

Why somebody down voted this question ? I am just asking my doubt. is it valid or not ? — Dhiral Kaniya
– Dhiral Kaniya, Commented Jun 30, 2017 at 7:16
Don't you just hate it when people downvote without criticism? It's a valid question for people not aware of the async nature of node. — Zeokav
– Zeokav, Commented Jun 30, 2017 at 7:41

nitishagar · Accepted Answer · 2017-06-16 06:18:01Z

2

We need the callback to finish to return a response, one of the way to solve this is using promises as shown below:

var ser = function(value) {
    var query = "SELECT * FROM tbl_api WHERE apikey = '" + value + "'";
    return new Promise(function (resolve, reject) {
       client.query(query, function(err, result) {         
           if (err) {
              return reject(err);
           } else {
              if (result.rowCount > 0) {
                  return resolve(true);
              } 
           }
           return resolve(false);
       });
   });
};
module.exports.checkAPI = ser;

And in your api.js changes to:

var express = require('express');
var app = express();
var apiCheck = require('./api.js');


//APIKey Generator check api
app.get('/apicheck/:apikey', function(request, response) {
    var value = request.params.apikey;
    apiCheck.checkAPI(value)
      .then(function(result) { response.send(result); })
      .catch(function(err) { response.send(err); });
});

edited Jun 16, 2017 at 6:18

answered Jun 16, 2017 at 6:06

nitishagar

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7 Comments

Dhiral Kaniya Over a year ago

what is promises ? like uses and all ? @nash_ag

Dhiral Kaniya Over a year ago

It give me an error as TypeError: Cannot read property 'then' of undefined.

nitishagar Over a year ago

Ahh - fixing the answer.

nitishagar Over a year ago

@DhiralKaniya Here are more details on promises - strongloop.com/strongblog/…

Dhiral Kaniya Over a year ago

I got my error. Sorry for above.. but is it possible to take res value inside some variable in web.js like var result = apiCheck.checkAPI(value)

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