I am using Express.js to build a small application. I have successfully implement the feature that allows me to add new entries to the database.
I am currently trying to delete an entry from a mysql db when a user clicks on a button. This is the code that gets executed:
client.query('DELETE FROM humans WHERE id= ?', [req.params.id], function(err, result) {
if (err) {
throw err;
}
res.redirect('/humans');
I know that the code executes properly because I get redirected to the correct page. Still, my entry is still in the database.
Deducing from the comments to your question I guess that you're sending the id from a form using a POST request. To find post params in req.body (if you're using the express.bodyParser middleware). Thus:
client.query('DELETE FROM humans WHERE id= ?', [req.body.id], function(err, result) {
if (err) {
throw err;
}
res.redirect('/humans');
});
If you're sending a GET request the param would be find in req.query.
Related
I'm just learning how to make a simple web-application for my dorm that would assign each participant a random number once they enter their name. There is a form field with one text box and a button. The text box (form) needs to send the full name (a single string) to the MySQL database so that later on I could retrieve the full list with the assigned numbers to actually use the application in the real world. Just for redundancy, I've put in code that creates a new database and a table every time, but then SQL ignores it if the DB and table already exist.
My fundamental problem is that I can not get data from my form in HTML. I'm using express.js and am trying to retrieve it, then post it into my database via the SQL module. Now as I'm a complete newbie, I have no idea how it should work. For the past 4 days, I've searched all over the internet to try to solve this issue. I don't know if the js document is the problem or the HTML document.
This is my HTML form (do tell me if you would need the whole thing):
<form action="/createPerson" method="POST">
<input type="text" name="name" value="Ime in priimek">
<input type="submit" name="name" value="Potrdi" class="gumbek">
</form>
And here is my complete node.js document:
var mysql = require('mysql');
var express = require("express");
var bodyParser = require("body-parser");
var urlencodedParser = bodyParser.urlencoded({
extended: false
});
const http = require('http');
var fs = require('fs');
const app = express();
const path = require('path');
const router = express.Router();
// Unique random number generator module
const uniqueRandom = require('unique-random');
app.use(express.static(__dirname + '/public'));
app.use(bodyParser.urlencoded({
extended: false
}));
app.use(bodyParser.json());
server = http.createServer(app);
server.listen();
// Start connecting to MySQL database
var con = mysql.createConnection({
host: "localhost",
user: "root",
password: "root",
database: "mydb"
});
//if database mydb exists, ignore database creation
let createMydb = "CREATE DATABASE if not exists mydb"
con.connect(function(err) {
if (err) throw err;
console.log("Connected!");
con.query(createMydb, function(err, result) {
if (err) throw err, console.log("Database already exists!");
console.log("Database OK (Already exists, will not create new one)");
});
});
//if table person exists, ignore table creation
let createTable = "CREATE TABLE if not exists person (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), number VARCHAR(255))";
var sql = createTable;
con.query(sql, function(err, result) {
if (err) throw err, console.log("Table exists, will not create new table");
console.log("Table OK (Already exists, will not create new one)");
console.log('Running at Port 3000');
console.log("Connected. Commencing value input into database.");
//var post = { name: req.body.name, number: random }
//app.get('/createPerson', urlencodedParser, function(err, req, res) {
if (err) throw err;
//res(req.body.name)
});
router.get('/', function(req, res) {
res.sendFile(path.join(__dirname + '/index.html'));
//__dirname : It will resolve to your project folder.
});
/*const random = uniqueRandom(1, 100);
const values = ['/createPerson', String(random())];
var insert = "INSERT INTO person (name, number) VALUES (?)"
con.query(insert, [values], function(err, result) {
if (err) throw err;
console.log("Value was inserted into database.");
});*/
app.get('/createPerson', function(req, res) {
res.render('form'); // if jade
// You should use one of line depending on type of frontend you are with
res.sendFile(__dirname + '/index.html'); //if html file is root directory
});
app.post('/createPerson', urlencodedParser, function(req, res) {
const random = uniqueRandom(1, 100);
const values = [String(req.body.name), String(random())];
var insert = "INSERT INTO person (name, number) VALUES (?)"
console.log(req.body.name);
con.query(insert, [values], function(err, result) {
if (err) throw err;
console.log("Value was inserted into database.");
res.sendFile(__dirname + '/numberAssigned.html');
res.end();
});
});
Now every time I press the button in the form, I get Cannot POST /createPerson inside the browser and no data was sent to my database. Browser (network tab) also gives me 404. Maybe it can't find the form?
I am a complete newbie at all of this, I can manage HTML and CSS, Javascript is something really new to me. If you find the time to help me, THANK YOU FROM THE BOTTOM OF MY HEART!
The problem is that you are using node.js http module and express at the same time.
You are setting up /createPerson within the express.js app, but starting the node.js http server instead. So, no end-points are present in the server you've started - hence 404 Page Not Found.
Usually, you use just one of them. Node.js http module provides an ability to start a low-level HTTP server. Express, on the other hand, is a more high-level solution for building http services. So in your case, I would stick with express and throw out http (express is using http module under the hood anyways).
But the fundamental problem of your solution is that it is too big and complex to bootstrap from scratch.
It could be really confusing to figure out what is going on in a complex app, since you are trying to do many things at once - express http server + sql database + html forms... Many things can go wrong, so better try a "Hello World" approach instead.
To debug a problem like that, I would downscale the app and try to check every little interaction level by level:
Level 1
Comment out http module usage and every mapping in express except POST for /createPerson
Make sure you run express app.listen() after the end-point setup.
Comment out all database access in /createPerson handler and leave just a log statement like that:
app.post('/createPerson', urlencodedParser, function(req, res) {
console.log(req.body.name);
}
Now run your script with node.js and try to check the POST on /createPerson with curl:
curl --data-urlencode "name=John Doe (Junior)" http://localhost:3000
(make sure you are using the right port)
Check node.js logs - you have to see a name you're sending with curl in there.
When you see the name in logs, Level 1 is complete!
Level 2
Now try to do the same POST, but form an HTML form.
Add a static mapping on /public to node.js.
Run the node.js server.
Open a page with the HTML form and POST it.
Make sure your form is sending data to correct URL and you see the data in node.js logs
Level 3
Only now, when you have data flowing from html to node.js, you can try to extend the system with a database. Reintegrate db access code back into /createPerson and debug the solution.
Good luck with the next levels!
I am building an application that has a backend that uses SQL queries to get data from a SQL Server database. However, I need to write a query that truncates and repopulates a table in that database using data from a second database. Here is what my code looks like:
// establishes a connection to serverName and uses DB1 as the database. But how can you access two?
global.config = {
user: 'username',
password: 'password',
server: 'serverName',
database: 'DB1'
};
// run this query. It's already been tested in SQL server and works fine there
let query = "TRUNCATE TABLE [DB1].[dbo].[Shop]; INSERT INTO [DB1].[dbo].[Shop] (Shop, shopDescription, Address, City)" +
" SELECT Shop, Description, Address, City FROM [DB2].[dbo].[ShopTable]"
new sql.ConnectionPool(config).connect().then(pool => {
return pool.request().query(query) }).then(
result => {
console.log(result.recordset)
//result returns as "undefined"
res.setHeader('Access-Control-Allow-Origin', '*')
res.status(200);
sql.close();
}).catch(err => { //error is not thrown
res.status(500).send({ message: err})
sql.close();
});
I get an "undefined" result, and find that no update to the table was made. The issue here isn't exactly clear whether it can't reach the table in DB2, or if perhaps the command doesn't work with the Node.js mssql package?
It appears this was a front end to back end connection issue. I was able to get the query to work without any changes to the database information, so it appears I can access the second database without any issues.
component.ts
this.httpService.patch('update', {} ).subscribe()
index.js
app.patch('/api/update', controllers.manualQueries.update);
I developed an Android app that save via http request some data in mongodb. everything is working fine and it's ok. Now it comes the second part of the project, to use this data in a html javascript, and I can't figure out how to do it.
This is from my server.js and it's the part where I get the data from database and I send it to localhost:3000 in res.send(data).
app.get('/',(req,res)=> {
MongoClient.connect(url, { useNewUrlParser: true }, function(err,
db) {
if (err) throw err;
var dbo = db.db("mydb");
dbo.collection("date_locatie").find({"imei" : imei_number},
function(err, result) {
if (err) throw err;
console.log(data.imei);
res.send(data);
});
});
});
Now I have made a html page called mapa.html and after I past data from mongo to node (res.send(data)) I've tried to send the html page too with res.sendFile(path.join(__dirname+'/mapa.html')) and it seems express/node.js not working like this. If I put the res.sendFile line after res.send I receive an error
Error: Can't set headers after they are sent.
I understand I can't res.sendFile after I res.send, but I can't figure out how I can use the data from mongodb in that html page.
You cannot pass variables to an html page. You must use a template engine. I recommend using EJS templates. You can install it by running npm install ejs, then inside your code specify the template engine that you are using by writing app.set('view engine', 'ejs');. The pages you create must have an extension .ejs. Now you can load the page using render, like this:
res.render('page name',{
variables: someVariable
});
And inside of your template print the passed variables with <%= variables %>
Hope my answer helps. If you have any questions feel free to ask.
i am working on a task where i am workking on create user. i am taking the inputs from the postman and i am validating all the fields and when ever all are validated correctly i am going to insert it in the database.. i am using mongo db as database. But whats the problem is i am taking inputs as first name ,lastname,userid and password and confirm password .. but when i am inserting it the connfirm password also inserting .. so i need to remove that particular field .
mongo.get().collection("customers").insertOne(req.body, function(err, res) {
if (err) throw err;
});
where mongo.get() is the database connection url
Well you can delete that property from your document/object before inserting into database.
Something like
delete req.body.confirmPasswordFiled
mongo.get().collection("customers").insertOne(req.body, function(err, res) {
if (err) throw err;
});
A web app I'm building will send out invoices to clients every third month. This will be a scheduled event that is run in the middle of the night, but under development I have put this code into a route so I can test it.
In short i want the code to do the following.
QUery all unsent invoices from DB.
Make a call to Mandrill for each invoice (In this call I'm also invoking a function creating a Mandrill message object from the invoice).
For every message Mandrill send, Update the DB invoice sent: true.
When all invoices are sent, make a final callback in the async.waterfall
The code below works. but i have some concerns regarding the _.each.
invoices.post('/invoices/send/', function(req, res, next) {
async.waterfall([
// Query all unsent invoices
function(callback) {
db.invoices.find({sent: false}).toArray(callback);
},
// Send all unsent invoices
function(invoices, callback) {
if (invoices.length === 0) {
var err = new Error('There are no unsent invoices');
err.status = 400;
return next(err); //Quick escape if there are no matching invoice to process
}
// Make a call to Mandrill transactional email service for every invoice.
_.each(invoices, function(invoice) {
mandrillClient.messages.sendTemplate({template_name: "planpal-invoice", template_content: null, message: mandrillClient.createInvoiceMessage(invoice)}, function(sendResult) {
console.log(sendResult);
db.invoices.updateById(invoice._id, {$set: {sent: true}}, function(err, saveResult) {
console.log(saveResult);
});
}, function(err) {
return next(err);
});
});
callback(null, 'done');
}
],
function(err, result) {
if (err) {
return next(err);
}
res.json(result);
});
});
I'm thinking I should use async.eachLimit instead.... but I dont know how to write it.
I have no idea what i should set the limit to, but I guess several parallel request would be better than running all mandrill request in serie like above, am I wrong? EDIT _.each run the callbacks in parallel. The difference from a async.each is that I dont get a "final callback"
Conclusion: Should i use a async.eachLimit above? If Yes, what is a good limit value?
I think you can use the https://github.com/caolan/async#each function.
it will execute the queries in parallel too