Express in server to perform a database query - node.js

Question

I want to know how ExpressJS works in the server side
I need some information on Server side, Main things are,As per my knowledge,
ExpressJS can perform all the functionalists of a PHP - - - IS it
true ?
My Client(Android) is ready to submit a POST request to Server
If i can send one single information in the form of (Key,value) pair,
can the Express accept that pair- - Identify the value based on key
and, to perform a sql query to Database based on the value received
from android client?
If it can how it does it?
MY Express Program ( It gives a Response without scenario explained above - How to modify this program )
var express = require('express')
, async = require('async')
, http = require('http')
, mysql = require('mysql');
var app = express();
var connection = mysql.createConnection({
host: 'localhost',
user: '*********',
password: "*****",
database: 'DB'
});
connection.connect();
// all environments
app.set('port', process.env.PORT || 7002);
//
//REQUEST FOR FIRST REQUEST
//
app.get('/',function(request,response){
var name_of_restaurants, RestaurantTimings;
async.series( [
// Get the first table contents
function ( callback ) {
connection.query('SELECT * FROM restaurants', function(err, rows, fields)
{
console.log('Connection result error '+err);
name_of_restaurants = rows;
callback();
});
},
// Get the second table contents
function ( callback ) {
connection.query('SELECT * FROM RestaurantTimings', function(err, rows, fields)
{
console.log('Connection result error '+err);
RestaurantTimings = rows;
callback();
});
}
// Send the response
], function ( error, results ) {
response.json({
'restaurants' : name_of_restaurants,
'RestaurantTimings' : RestaurantTimings
});
} );
} );
http.createServer(app).listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port'));
});
Hope I am clear
Thanks ,

Answer 1

You can send information via query params or as part of the url path. If you send it as a query param, you can access it using
req.query.keyName;
If you want to send the value as part of the url, you'll have to add a route to accept it. You can accept variable content in a url by using the :keyName form. Express will capture it in req.params. So it would look a little like this:
app.get('/some/url/:keyName', function(req, res, next){
var keyName = req.params.keyName;
// . . .
});
Then you can send your http request to '/some/url/someKeyValue' and the variable keyName will then be equal to whatever you add after /some/url/.
If you're POSTing data in the body of the request, access it with req.body.keyName.
EDIT: Here's an attempt at using the original code. Note that I'm still making up values and guessing at what the intent is.
var express = require('express')
, async = require('async')
, http = require('http')
, mysql = require('mysql');
var app = express();
var connection = mysql.createConnection({
host: 'localhost',
user: '*********',
password: "*****",
database: 'DB'
});
connection.connect();
// all environments
app.set('port', process.env.PORT || 7002);
//
//REQUEST FOR FIRST REQUEST
//
app.get('/',function(request,response){
var name_of_restaurants, RestaurantTimings;
async.series( [
// Get the first table contents
function ( callback ) {
connection.query('SELECT * FROM restaurants WHERE name = ' . request.body.name, function(err, rows, fields) {
console.log('Connection result error '+err);
name_of_restaurants = rows;
callback();
});
},
// Get the second table contents
function ( callback ) {
connection.query('SELECT * FROM RestaurantTimings', function(err, rows, fields) {
console.log('Connection result error '+err);
RestaurantTimings = rows;
callback();
});
}
// Send the response
], function ( error, results ) {
response.json({
'restaurants' : name_of_restaurants,
'RestaurantTimings' : RestaurantTimings
});
} );
} );
http.createServer(app).listen(app.get('port'), function(){
console.log('Express server listening on port ' + app.get('port'));
});
But you should really not query directly like that because of SQL injection. I've never used MySQL from node, but I'm sure there is some way to use parameterized queries. Hope this is more helpful.
Also, I'm assuming that the data will be passed in the request body, since you said you are ready to POST to the server.