I have tried to pass a variable from my index.html to the database(maildata.js) through app.js(server) and get the corresponding data
I am able to get the data from the database but couldnt send that back to the server(app.js)
app.js
var express = require('express');
var maildata= require('./maildata');
var app = express();
app.configure(function(){
app.use(express.bodyParser());
});
app.get('/', function(request, response){
response.sendfile(__dirname + '/mailbox.html');
});
app.post('/mailboxpost',function(request, response) {
var input=request.query.search;
var result=maildata.getMailData(input);
response.send(result);
response.end();
});
app.listen(8888);
console.log('Server is running on port 8888');
maildata.js
exports.getMailData=function(data,response) {
var stop_name= data;
connection.query("select stop_name,stop_comment from stoplist where stop_name= '"+stop_name+"' limit 1",function(err, rows) {
if (err) {
console.log('error in fetching ' + err);
}
else{
var jsonString1= JSON.stringify(rows);
connection.query("select mailbox_sequence_no from stoplist where stop_name= '"+stop_name+"'",function(err, rows) {
if (err) {
console.log('error in fetching ' + err);
}
else{
var jsonString2 = JSON.stringify(rows);
connection.query("select party_head from stoplist where stop_name= '"+stop_name+"'", function(err, rows) {
if (err) {
console.log('error in fetching ' + err);
}
else{
var jsonString3 = JSON.stringify(rows);
var result=jsonString1+'/'+jsonString2+'/'+jsonString3;
response.send(result);
}
});
}
});
}
});
}
Thanks in Advance
How about sending response along when you call the function?
var result=maildata.getMailData(input); // something missing here
Your getMailData function expects two arguments:
exports.getMailData=function(data,response) { ... }
but you give it only one:
var result=maildata.getMailData(input);
Which makes the value of the response argument undefined.
Here is what you should do:
app.post('/mailboxpost',function(request, response) {
var input=request.query.search;
maildata.getMailData(input, response);
});
and let maildata.getMailData handle the response sending, as you did in response.send(result);
I have used asynchronous callback method in my app.js.
I got the result
var result=maildata.getMailData(input,response,function(data){
response.send(data);
response.end();
});
Thanks all
Related
I have two file in my node js app server.js and database.js
//server.js
var db = require('./database.js');
var express = require('express');
var app = express();
var server = app.listen(8081, '000.00.00.000',function(){
var host = server.address().address;
var port = server.address().port
console.log('App listening');
})
app.get('/',function(req,res){
res.end("Hello Jamian");
})
app.get('/insertuser',function(req,res){
console.log("insert user called")
var result = new db.insertUser();
console.log("result " + result)
});
and
//database.js
var mysql = require('mysql');
var con = mysql.createConnection({
host:"localhost",
user:"0000",
password:"0000",
database: "aaaa"
});
con.connect(function(err){
if(err) throw err;
console.log("DB Connected");
});
module.exports = {
insertUser: function () {
console.log("module exported");
var SQL_insert_user = "insert into users(username,useremail,usermobile,userpassword,activetoken) values('darren','darren#yahoo.in','980000000','password','ASKDO5615F')";
con.query(SQL_insert_user,function(err,result){
if(err) throw err;
console.log("data inserted");
return result;
});
},
bar: function () {
console.log("bar called")
}
};
I need a callback from the insertUser function in database.js so i can call a res.end("data inserted"). however it seems con.query is going async, hence I am getting a blank value when I try to log result in server.js from get/insertuser in server.js
data inserted
insert user called
module exported
result {}
data inserted
Use promises. Either native or from a library.
Here's how you could do it with a promise:
insertUser: function(){
return new Promise(function(reject, resolve){
var SQL_insert_user = "insert into users(username,useremail,usermobile,userpassword,activetoken) values('darren','darren#yahoo.in','980000000','password','ASKDO5615F')";
con.query(SQL_insert_user,function(err,result){
if(err) reject(err);
else resolve(result);
});
});
},
Then you can use it your other file like this:
insertUser()
.then(function(result){
// do something with the result
})
.catch(function(err){
// Oh no! there was an error!
});
in your server js do
app.get('/insertuser',function(req,res){
console.log("insert user called")
var result = new db.insertUser(function(result) {
console.log("result " + result)
});
});
and in your database do
module.exports = {
insertUser: function (cb) {
console.log("module exported");
var SQL_insert_user = "insert into users(username,useremail,usermobile,userpassword,activetoken) values('darren','darren#yahoo.in','980000000','password','ASKDO5615F')";
con.query(SQL_insert_user,function(err,result){
if(err) throw err;
console.log("data inserted");
cb(result);
});
},
bar: function () {
console.log("bar called")
}
};
I would like to be able to read data received by the ascii command sent.
Below is the code that sends command to my lock controller
var express = require('express');
var router = express.Router();
var SerialPort = require('serialport');
/* GET home page */
router.get('/', function(request, response){
SerialPort.list(function (err, ports) {
ports.forEach(function(port) {
console.log(port.comName);
console.log(port.pnpId);
console.log(port.manufacturer);
});
});
var port = new SerialPort("COM5", {
baudRate: 38400
});
port.on('open', function() {
// NodeJS v4 and earlier
port.write(new Buffer('status1', 'ascii'), function(err) {
if (err) {
return console.log('Error on write: ', err.message);
}
console.log('message written');
});
});
// open errors will be emitted as an error event
port.on('error', function(err) {
console.log('Error: ', err.message);
});
});
// Important
module.exports = router;
In the doc, it mentions the use of parsers to try and read data, https://github.com/EmergingTechnologyAdvisors/node-serialport#serialportparsers--object but I am not sure how to implement it, and I would want to execute after the command status1 has been written.
Essentially logs the response of the command succesfully written to the console
There are some peculiarities.
You can open port on application start and reconnect on port close or open port on each request. It defines how work with data flow. If you send request to port then answer can contain data of previous requests (more than one). You can ignore this problem (if answer is short and request interval is enough large) or send request with assign id and search answer with this id.
SerialPort.list(function (err, ports) {
ports.forEach(function(port) {
console.log(port.comName, port.pnpId, port.manufacturer); // or console.log(port)
});
});
router.get('/', function(req, res){
function sendData(code, msg) {
res.statusCode = 500;
res.write(msg);
console.log(msg);
}
var port = new SerialPort("COM5", {
baudRate: 38400
});
port.on('open', function() {
port.write(Buffer.from('status1', 'ascii'), function(err) {
if (err)
return sendData(500, err.message);
console.log('message written');
});
});
var buffer = '';
port.on('data', function(chunk) {
buffer += chunk;
var answers = buffer.split(/\r?\n/); \\ Split data by new line character or smth-else
buffer = answers.pop(); \\ Store unfinished data
if (answer.length > 0)
sendData(200, answer[0]);
});
port.on('error', function(err) {
sendData(500, err.message);
});
});
module.exports = router;
I have just made a simple program to display and insert data from a database(sql server 2008). My code does the display of data. I am unable to get data inserted. It shows no error in terminal or browser.
Here is my javascriptfile
var express = require('express');
var app = express();
app.use(express.static('public'));
app.get('/htm', function (req, res) {
res.sendFile( __dirname + "/" + "index.html" );
})
var sql = require("mssql");
var config = {
user: 'pkp',
password: 'pkp',
server: 'PRAVEEN\\SQLEXPRESS',
database: 'myneww'
};
app.get('/process_get', function (req, res) {
// Prepare output in JSON format
response = {
first_name:req.query.first_name,
last_name:req.query.last_name
};
sql.connect(config, function (err) {
if (err) console.log(err);
var request = new sql.Request();
console.log(req.query.first_name);
var res=request.query('insert into Mytab values(req.query.first_name ,req.query.last_name)');
});
});
app.get('/alldata', function (req, res) {
sql.connect(config, function (err) {
if (err) console.log(err);
// create Request object
var request = new sql.Request();
// query to the database and get the records
request.query('select * from Mytab', function (err, recordset) {
if (err) console.log(err)
// send records as a response
res.send(recordset);
});
});
});
var server = app.listen(8081, function () {
var host = server.address().address
var port = server.address().port
console.log("Example app listening at http://%s:%s", host, port)
})
Here is my html file
<html>
<body>
<form action="http://127.0.0.1:8081/process_get" method="GET">
First Name: <input type="text" name="first_name"> <br>
Last Name: <input type="text" name="last_name">
<input type="submit" value="Submit">
</form>
</body>
</html>
I am able to get the values displayed in the console, means values are passed and retrieved from the form. But still not inserted into the database.
I'm not good in javascript, but I guess the line below is incorrect:
var res=request.query('insert into Mytab values(req.query.first_name ,req.query.last_name)');
It should be something like this.
var res=request.query('insert into Mytab values(' + req.query.first_name + ',' + req.query.last_name +')');
If not, you've got an idea.
First, you were not passing values properly to query and, secondly, you are not waiting for the record to insert. Add the callback that I added.
app.get('/process_get', function (req, res) {
//some code
sql.connect(config, function (err) {
if (err) console.log(err);
var request = new sql.Request();
console.log(req.query.first_name);
request.query('insert into Mytab values('+req.query.first_name+','+req.query.last_name+')', function(err, recordset) {
if (err) {
console.log(err);
return res.send('Error occured');
}
return res.send('Successfully inserted');
});
});
});
Update
Use transaction to commit changes.
app.get('/process_get', function (req, res) {
//some code
var sqlConn = new sql.Connection(config);
sqlConn.connect().then(function () {
var transaction = new sql.Transaction(sqlConn);
transaction.begin().then(function () {
var request = new sql.Request(transaction);
request.query('Insert into EmployeeInfo (firstName,secondName) values ('+req.query.first_name+','+req.query.last_name+')').then(function () {
transaction.commit().then(function (recordSet) {
console.log(recordSet);
sqlConn.close();
return res.send('Inserted successfully');
}).catch(function (err) {
console.log("Error in Transaction Commit " + err);
sqlConn.close();
return res.send('Error');
});
});
});
});
Forgive me, if there is any typo.
I woudl like to print file to res.write() method but I get error:
TypeError: First argument must be a string or Buffer
My code:
var fs = require("fs");
var http = require("http");
http.createServer(function (req, res){
res.write(getData());
res.end();
}).listen(3333);
function getData(){
fs.readFile('testfs.txt', function(err, data){
if(err)
{
console.log("Error: " + err);
}else {
console.log(data.toString());
return data.toString();
}
});
}
What's the problem?
res.write didn't get string nor buffer because your function getData wasn't asynchronous. Here's the fix I hope will solve your problem:
http.createServer(function (req, res){
getData(function(data){
res.write(data);
res.end();
}));
}).listen(3333);
function getData(cb){
fs.readFile('testfs.txt', function(err, data){
if(err)
{
console.log("Error: " + err);
}else {
cb(data.toString());
}
});
}
Where cb argument is a callback function obviously.
Alternatively, you can use streams:
const http = require('http');
const fs = require('fs');
http.createServer((req, res) => {
fs.createReadStream('testfs.txt')
.on('error', (e) => {
console.log('Error:', e);
res.statusCode = 500;
res.end();
})
.pipe(res)
}).listen(3333);
Do it the other way around; just call getData and pass in response, then when the file is loaded, call response.end(string).
I have a route I that in order to get all the data needs to access the API server multiple times (according to the data that was given).
Now I need to add a third access to the server and it's getting rather unreadable.
The following code is working, but I have a feeling I'm not doing it right (promises?) - couldn't figure out what exactly is recommended in this case
The code: (stripped down to emphasise the point)
router.get('/', function(req, main_response) {
http.get(FIRST_API_COMMAND, function (res) {
var moment_respose_content = '';
res.on("data", function (chunk) {
moment_respose_content += chunk;
});
res.on('end',function(){
if (res.statusCode < 200 || res.statusCode > 299) {
main_response.send('error in getting moment');
return;
}
var response = JSON.parse(moment_respose_content );
if (response.success)
{
var data = response.data;
//doing something with the data
http.get(SECOND_API_COMMAND, function (res) {
res.on("data", function (chunk) {
comment_respose_content += chunk;
});
res.on('end',function(){
var response = JSON.parse(comment_respose_content);
if (response.success)
{
var comments = response.data;
main_response.render('the page', {data: data});
return;
}
});
}).on('error', function (e) {
console.log("Got error: " + e.message);
main_response.send('Error in getting comments');
});
return;
}
});
}).on('error', function (e) {
console.log("Got error: " + e.message);
main_response.send('Error in getting moment');
});
});
You can write a middleware for each remote action, and then use those middlewares before the get handler, so the get handler can simply access their results. (Promises can help if you need to start subsequent requests before waiting for earlier ones to finish, but that situation is rare.)
For example, using express middleware to fetch each remote data independently:
var request = require('request');
var express = require('express');
var app = express();
var router = express.Router();
/* middleware to fetch moment. will only run for requests that `router` handles. */
router.use(function(req, res, next){
var api_url = 'https://google.com/';
request.get(api_url, function(err, response, body) {
if (err) {
return next(err);
}
req.moment_response = response.headers["date"];
next();
});
});
/* middleware to fetch comment after moment has been fetched */
router.use(function(req, res, next){
var api_url = 'https://www.random.org/integers/?num=1&min=1&max=100&col=1&base=10&format=plain&rnd=new';
request.get(api_url, function(err, response, body){
if (err) {
return next(err);
}
req.comment_response = parseInt(body);
next();
});
});
/* main get handler: expects data to already be loaded */
router.get('/', function(req, res){
res.json({
moment: req.moment_response,
comment: req.comment_response
});
});
/* error handler: will run if any middleware called next() with an argument */
router.use(function(error, req, res, next){
res.status(500);
res.send("Error: " + error.toString());
});
app.use('/endpoint', router);
app.listen(8000);
Often the remote data you want to fetch is based on some parameter of the main request. In this case you would want to use req.param() instead of App.use() to define the data-loading middleware.