I would like to know how can you check the row count of the query in PostgreSQL in node.js
I have this code for the meantime.
var client = new pg.Client(conString);
client.connect();
var query = client.query("SELECT * FROM users");
query.on('row', function(row) {
console.log(row);
});
var client = new pg.Client(conString);
client.connect();
client.query("SELECT * FROM users", function(err, result) {
console.log("Row count: %d",result.rows.length); // n
});
Another options is to use the rowCount property! Like this:
var pg = require('pg');
var pgClient = new pg.Client();
pgClient.connect();
var pgQuery = pgClient.query("SELECT * FROM information_schema.tables;");
pgQuery.on('error', function(err) {
pgClient.end();
console.error(err);
});
pgQuery.on('end', function(result) {
pgClient.end();
console.log(result.rowCount);
});
or like this:
var pg = require('pg');
var pgClient = new pg.Client();
pgClient.connect();
var pgQuery = pgClient.query("SELECT * FROM information_schema.tables;", function(err, result) {
pgClient.end();
if (err) return console.error(err);
console.log(result.rowCount);
});
Related
Problem I try get data from RDS PostgreSQL via Lambda function with Nodejs but response return is message
Execution result: failed with "errorMessage": "2017-07-05T15:05:27.425Z 596fdf39-6193-11e7-9176-f58796899f9b Task timed out after 3.00 seconds" }
This snip code:
const pg = require('pg');
exports.handler = (event, context, callback) => {
var conn = "pg://string connect database";
var client = new pg.Client(conn);
client.connect();
var resss = [];
var idUser = 2;
var query = client.query({
text: 'SELECT * from users where id= $1',
values: [idUser]
});
query.on("row", function (row, result) {
result.addRow(row);
});
query.on("end", function (result) {
var jsonString = JSON.stringify(result.rows);
var jsonObj = JSON.parse(jsonString);
resss.push(jsonObj);
client.end();
context.done(null, jsonObj);
});
callback(null, resss);
};
<
This is connection.js
var MongoClient = require('mongodb').MongoClient;
var db_singleton = null;
var getConnection= function getConnection(callback) {
if (db_singleton) {
callback(null,db_singleton);
} else {
var connURL = "mongodb://localhost:27017/testdb";
MongoClient.connect(connURL,function(err,db){
if(err)
console.log("Error creating new connection "+err);
else
{
db_singleton=db;
console.log("created new connection");
}
callback(err,db_singleton);
});
}
};
module.exports = getConnection;
And this is product.js
var getConnection = require('../../connection.js');
var products = null;
getConnection(function(err,db) {
var collection = db.collection("products");
collection.find().toArray(function(err, productsDB) {
products = productsDB;
})
});
console.log(products);
module.export = products;
console.log(products) is always null.
But it should be object.I would like to cache variable when server starts.
I use mongodb and in mongodb I put my username and password.
The code is:
var mongodb = require('mongodb');
var http = require('http');
var fs=require('fs');
var express = require('express');
var bodyParser = require('body-parser');
var app = express();
app.use(bodyParser());
app.listen(8080, function() {
console.log('Server running at http://127.0.0.1:8080/');
});
app.post('/prova', function(req, res) {
// res.send('You sent the name "' + req.body.username + '".');
var MongoClient = mongodb.MongoClient;
// Connection URL. This is where your mongodb server is running.
var url = 'mongodb://localhost:27017/utente';
MongoClient.connect(url, function (err, db) {
if (err) {
console.log('Unable to connect to the mongoDB server. Error:', err);
} else {
//HURRAY!! We are connected. :)
console.log('Connection established to', url);
var collection = db.collection('login');
// var prova1=({name:"documento1",url:"sadsad",tag:"dc1"});
// do some work here with the database.
var cursor = collection.find();
cursor.each(function (err, doc) {
if (err) {
console.log(err);
} else {
// console.log('Fetched:', doc);
var username=0;
var password=0;
for(valore in doc){
if(valore!="_id"){
if(valore=="username"){
if(doc[valore]==req.body.username){
username=1;
}
}
if(valore=="password"){
if(doc[valore]==req.body.password){
password=1;
}
}
}
}
if(username==1 && password==1){
console.log("entra");
// res.end();
}else{
fs.readFile('C:\\Users\\Eventi\\Desktop\\Node.js\\Progetti\\ProveNodeJS\\NodeJSProve\\paginaRifiuto.html', function (err, html) {
if (err) {
}
res.writeHeader(200, {"Content-Type": "text/html"});
res.write(html);
res.end(html);
});
}
}
});
//Close connection
}
});
});
http.createServer(function(request, response) {
fs.readFile('C:\\Users\\Eventi\\Desktop\\Node.js\\Progetti\\ProveNodeJS\\NodeJSProve\\home.html', function (err, html) {
if (err) {
}
response.writeHeader(200, {"Content-Type": "text/html"});
response.write(html);
response.end();
});
}).listen(8000);
I call first http://localhost:8000 and I put in a text field the wrong value of username and password and after I click login I see my "login fail page" but I obtain this error:
Connection established to mongodb://localhost:27017/utente
_http_outgoing.js:335
throw new Error('Can\'t set headers after they are sent.');
^
Error: Can't set headers after they are sent.
at ServerResponse.OutgoingMessage.setHeader (_http_outgoing.js:335:11)
at ServerResponse.writeHead (_http_server.js:195:21)
at ServerResponse.writeHeader (_http_server.js:233:18)
at C:\Users\Eventi\Desktop\Node.js\Progetti\ProveNodeJS\NodeJSProve\HelloWord.js:67:23
at fs.js:334:14
at FSReqWrap.oncomplete (fs.js:95:15)
I want build a class for wrapping database connection. This is my code ('db.js' file):
var mongodb = require('mongodb');
var Class = function() {
this.db = null;
var server = new mongodb.Server('127.0.0.1', 27017, {auto_reconnect: true});
db = new mongodb.Db('myDB', server);
db.open(function(error, db) {
if (error) {
console.log('Error ' + error);
} else {
console.log('Connected to db.');
this.db = db;
}
});
};
module.exports = Class;
Class.prototype = {
getCollection: function(coll_name) {
this.db.collection(coll_name, function(error, c){ // <--- see error below
return c;
});
}
}
exports.oid = mongodb.ObjectID;
Then, my test code ('test.js' file):
var DB = require('./db');
var myDB = new DB();
myDB.getCollection('myCollection'); // <--- error: Cannot call method 'collection' of null
You are missing "this" in front of "db". eg:
this.db = new mongodb.Db('myDB', server);
And the line next to it.
I've got a node.js script that loads an XML file. It loops through each element in the Mongo array and says that they're all getting inserted correctly, but when the script has completed a check of db.collection.count(); tells me that far fewer records have been inserted into the database than the number expected.
How can I make mongo and node.js play nicely with inserts?
GrabRss = function() {
var http = require('http');
var sys = require('sys');
var xml2js = require('xml2js');
var fs = require('fs');
var Db = require('../lib/mongodb').Db,
Conn = require('../lib/mongodb').Connection,
Server = require('../lib/mongodb').Server,
// BSON = require('../lib/mongodb').BSONPure;
BSON = require('../lib/mongodb').BSONNative;
var data;
var checked = 0;
var len = 0;
GotResponse = function(res) {
var ResponseBody = "";
res.on('data', DoChunk);
res.on('end', EndResponse);
function DoChunk(chunk){
ResponseBody += chunk;
}
function EndResponse() {
//console.log(ResponseBody);
var parser = new xml2js.Parser();
parser.addListener('end', GotRSSObject);
parser.parseString(ResponseBody);
}
}
GotError = function(e) {
console.log("Got error: " + e.message);
}
GotRSSObject = function(r){
items = r.item;
//console.log(sys.inspect(r));
var db = new Db('myrssdb', new Server('localhost', 27017, {}), {native_parser:false});
db.open(function(err, db){
db.collection('items', function(err, col) {
len = movies.length;
for (i in items) {
SaveItem(items[i], col);
}
});
});
}
SaveItem = function(m, c) {
/* REPLACE FROM HERE IN ANSWER */
c.find({'id': m.id}, function(err, cursor){
cursor.nextObject(function(err, doc) {
if (doc == null) {
c.insert(m, function(err, docs) {
docs.forEach(function(doc) {
console.log('Saved: '+doc.id+' '+doc.keywords);
});
});
} else {
console.log('Skipped: '+m.id);
}
if (++checked >= len) {
process.exit(0);
}
});
});
/* REPLACE TO HERE IN ANSWER */
}
//http.get(options, GotResponse).on('error', GotError);
var x2js = new xml2js.Parser();
fs.readFile('/home/ubuntu/myrss.rss', function(err, data) {
x2js.parseString(data);
});
x2js.addListener('end', GotRSSObject);
}
GrabRss();
As requested, the code is above. The file is read locally (though is used to be an HTTP request, but it's a 25 meg file now, lots of RSS records)
I just ran the file with some ~10k records in it and a count of the items in the mongoDB after the script has run is about 800 items.
As per the answer I replaced the insert code:
with:
c.update({'id': m.id}, {$set: m}, {upsert: true, safe: true}, function(err){
if (err) console.warn(err.message);
else console.log(m.keywords);
if (++checked >= len) {
console.log(len);
//process.exit(0);
process.exit(0);
}
});
By default, MongoDB writes do not check for an error.
You need to set safe:true in the options to your insert, as explained in the documentation for node-mongodb-native:
var collection = new mongodb.Collection(client, 'test_collection');
collection.insert({hello: 'world'}, {safe:true},
function(err, objects) {
if (err) console.warn(err.message);
if (err && err.message.indexOf('E11000 ') !== -1) {
// this _id was already inserted in the database
}
});
Otherwise your callback will not be invoked for errors and your client won't know about them.
You probably also want to look at upserts and updates, as it is incredibly inefficient to do find & insert if null in a loop.
Instead, upsert will update if the matching document exists, otherwise it will insert a new one. An explanation on how to do this in Node is in the documentaiton for the driver.