I am making database connection with React-native. I want to capture the data I saved elsewhere in this class. But I'm having the problem I wrote below.
Error Code: const warnedKeys: {[string]: boolean} = {};
const AsyncStorage = require('react-native');
const express = require('express');
const app = express();
const mysql = require('mysql');
const bodyParser = require('body-parser');
const cors = require('cors');
app.use(bodyParser.json());
app.use(cors());
const db = mysql.createConnection({
});
db.connect();
AsyncStorage.getItem('155').then(value =>
console.log(value)
);
app.get('/', function(req,res){
var sql = 'SELECT ID FROM ...TBL_STT';
db.query(sql, (err, result)=>{
if(err) throw err;
console.log(result);
res.send(result);
});
});
app.listen(3210, ()=>{
console.log('Server aktif di port 3210')
});
There is no value assigned to your db variable. The const must be assigned an unconditional value, such as a letter in JavaScript.
You can change this value const db => let db
import {AsyncStorage} from 'react-native';
...
let db = mysql.createConnection({ });
I've got an Express/Mongoose app that keeps throwing "cyclic dependency detected" errors at me. I've localized the problem to one of these files.
app.js
var express = require('express');
var mongoose = require('mongoose');
mongoose.connect('mongodb+srv://username:MY.PASSWORD#cluster0-6vlss.mongodb.net/test?retryWrites=true');
require('./models/Users');
var indexRouter = require('./routes/index');
var usersRouter = require('./routes/users');
var app = express();
routes/users.js
var mongoose = require('mongoose');
var express = require('express');
var router = express.Router();
var User = mongoose.model('User');
router.route('/user/:id')
.get((req, res, next) => {
User.findById(req.params.id, (err, user) => {
if (err) return next(err);
res.json(user);
});
});
models/Users.js
var mongoose = require('mongoose');
var UserSchema = mongoose.Schema({
_id: String,
username: {type: String, unique: true},
hash: String,
salt: String,
chats: Array
});
var User = mongoose.model('User', UserSchema);
module.exports = User;
Hopefully I condensed my code well enough. Could somebody point to my screw-up?
Got it. In app.js, dbconfig is an object that stores the database URI string. I called "dbconfig" directly instead of "dbconfig.url". Everything's good now.
I am trying to set up a react express application with mongo db as the database. I am in the preliminary stages and keep coming across this error:
Error: Route.post() requires callback functions but got a [object Undefined]
here is my app.js
const express = require('express');
// const http = require('http');
const bodyParser = require('body-parser');
const morgan = require('morgan');
const app = express();
const mongoose = require('mongoose');
mongoose.Promise = global.Promise;
//db and name is auth
mongoose.connect('mongodb://localhost/auth', {
useMongoClient: true,
/* other options */
});
// app setup
//server setup
const port = process.env.Port || 4000
// const server = http.createServer(app);
app.listen(port);
console.log(`Sever listening on ${port}`)
const authRoutes = require('./routes/auth_routes');
app.use('/',authRoutes);
my routes are right here. I am just testing to see if there is a correct connection.
const authController = '../controllers/auth_controller';
const express = require('express');
const authRoutes = express.Router();
authRoutes.post('/',authController.signup)
module.exports = authRoutes;
my controller is listed below:
const authController = {};
authController.signup = function(req,res,next) {
console.log('here');
res.json({
user: "doesnt matter",
data: 'Put a user profile on this route'
});
}
module.exports = authController;
not sure if mongo is the problem since it is my first time using it, but my connection to the database works robo 3t to check whats in the database and the user schema is there. if i comment out that one route in the routes page, the errors go away.
I believe the problem is here:
const authController = '../controllers/auth_controller';
authRoutes.post('/',authController.signup)
Note that authController is just a string. I'm guessing you intended:
const authController = require('../controllers/auth_controller');
Here is my routes/users.js file:
var express = require('express');
var router = express.Router();
/*
* GET userlist.
*/
router.get('/userlist', function(req, res) {
var db = req.db;
var collection = db.get('userlist');
collection.find({},{},function(e,docs){
res.json(docs);
});
});
module.exports = router;
In this code, what is the req object? And when we call req.db... that's made available to us via this right in app.js:
var mongo = require('mongodb');
var monk = require('monk');
var db = monk('localhost:27017/nodetest2');
var routes = require('./routes/index');
var users = require('./routes/users');
var app = express();
app.use(function(req,res,next){
req.db = db;
next();
});
What is the app.use exactly doing here?
I'm trying to create a really simple node API using express.js 4 but I need a few 'realtime' events for which I added socket.io. I'm fairly new to both so I'm likely missing something basic but I can't find good docs/tuts on this.
In the express app (created with the express generator) I have something like this based on simple examples and project docs that I read. This works OK and from client apps, I can send/receive the socket events:
var express = require('express');
var path = require('path');
var logger = require('morgan');
var api = require('./routes/api');
var app = express();
var io = require('socket.io').listen(app.listen(3000));
app.use(logger('dev'));
app.use(express.static(path.join(__dirname, 'public')));
app.use('/api', api);
io.sockets.on('connection', function (socket) {
console.log('client connect');
socket.on('echo', function (data) {
io.sockets.emit('message', data);
});
});
// error handlers omitted
module.exports = app;
but I want to use the sockets from my API routes (in the ./routes/api.js file that I 'require' above). For example, someone might use the API to PUT/POST a resource and I want that broadcast to connected socket.io clients.
I cannot see how to use the 'io' variable or organise the code currently in the io.sockets.on('connection' ... function inside express routes. Here's the ./routes/api.js file:
var express = require('express');
var router = express.Router();
var io = ???;
router.put('/foo', function(req, res) {
/*
do stuff to update the foo resource
...
*/
// now broadcast the updated foo..
io.sockets.emit('update', foo); // how?
});
module.exports = router;
One option is to pass it in to req object.
app.js:
var express = require('express');
var path = require('path');
var logger = require('morgan');
var api = require('./routes/api');
var app = express();
var io = require('socket.io').listen(app.listen(3000));
app.use(logger('dev'));
app.use(express.static(path.join(__dirname, 'public')));
io.sockets.on('connection', function (socket) {
console.log('client connect');
socket.on('echo', function (data) {
io.sockets.emit('message', data);
});
});
// Make io accessible to our router
app.use(function(req,res,next){
req.io = io;
next();
});
app.use('/api', api);
// error handlers omitted
module.exports = app;
./routes/api.js:
var express = require('express');
var router = express.Router();
router.put('/foo', function(req, res) {
/*
do stuff to update the foo resource
...
*/
// now broadcast the updated foo..
req.io.sockets.emit('update', foo);
});
module.exports = router;
I've modified your files a little bit, may you check if it works?
You can pass the io you've defined to your routes like below;
require('./routes/api')(app,io);
I didn't test the Socket.IO parts but there is no syntax error and routes also working.
server.js file:
var express = require('express');
var app = express();
var path = require('path');
var logger = require('morgan');
var io = require('socket.io').listen(app.listen(3000));
app.use(logger('dev'));
app.use(express.static(path.join(__dirname, 'public')));
io.sockets.on('connection', function (socket) {
console.log('client connect');
socket.on('echo', function (data) {
io.sockets.emit('message', data);
});
});
require('./routes/api')(app,io);
console.log("Server listening at port 3000");
api.js:
module.exports = function(app,io) {
app.put('/foo', function(req, res) {
/*
do stuff to update the foo resource
...
*/
// now broadcast the updated foo..
console.log("PUT OK!");
io.sockets.emit('update'); // how?
res.json({result: "update sent over IO"});
});
}
Supposing you want to access the SocketIO from anywhere in your application, not just in the router, you could create a singleton for it. This is what works for me:
//socket-singletion.js
var socket = require('socket.io');
var SocketSingleton = (function() {
this.io = null;
this.configure = function(server) {
this.io = socket(server);
}
return this;
})();
module.exports = SocketSingleton;
Then, you need to configure it using your server:
//server config file
var SocketSingleton = require('./socket-singleton');
var http = require('http');
var server = http.createServer(app);
SocketSingleton.configure(server); // <--here
server.listen('3000');
Finally, use it wherever you want:
//router/index.js
var express = require('express');
var router = express.Router();
var SocketSingleton = require('../socket-singleton');
/* GET home page. */
router.get('/', function(req, res, next) {
setTimeout(function(){
SocketSingleton.io.emit('news', {msg: 'success!'});
}, 3000);
res.render('index', { title: 'Express' });
});
module.exports = router;
One more option is to use req.app.
app.js
const express = require('express');
const path = require('path');
const logger = require('morgan');
const api = require('./routes/api');
const app = express();
const io = require('socket.io').listen(app.listen(3000));
// Keep the io instance
app.io = io;
app.use(logger('dev'));
app.use(express.static(path.join(__dirname, 'public')));
// ...
app.use('/api', api);
module.exports = app;
routes/api.js
const express = require('express');
const router = express.Router();
router.put('/foo', function(req, res) {
/*
* API
*/
// Broadcast the updated foo..
req.app.io.sockets.emit('update', foo);
});
module.exports = router;
Refactored Edudjr's answer.
Change the singleton to create a new instance of socket.io server
const { Server } = require('socket.io');
const singleton = (() => {
this.configure = (server) => this.io = new Server(server)
return this
})();
module.exports = singleton
Initialise your express app, the server and the singleton.
// initialise app
const app = express();
const server = require('http').createServer(app);
// configure socket.io
socket.configure(server)
Then in your router
const socket = require('/utils/socket-singleton');
socket.io.emit('event', {message: 'your message here'})
I think best way is to set io as a property of req, like below:
app.use(function(req,res,next){
req.io = io;
next();
});
app.use('/your-sub-link', your-router);