I'm trying to return a value from a class but it's coming up undefined.
index.js
import DB from "./db.js"
import express from "express";
import cors from "cors";
const database = new DB();
app.get("/", (req, res) => {
const data = database.selectAllFromProducts();
console.log(data); // Returns undefined
});
app.listen(process.env.PORT, () =>
console.log(`Listening on Port ${process.env.PORT}`)
);
db.js
class DB {
constructor() {
this.connection = this.initialize();
}
initialize() {
return mysql.createConnection({
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASSWORD,
database: process.env.DB_NAME,
});
selectAllFromProducts() {
this.initialize();
this.connection.query(`select * from ${process.env.DB_PRODUCTS_TABLE};`,
(err, results, fields) => {return results});
}
}
I have a front end that is sending the GET request and that is successful so it's not a routing problem. Console.logging the results works from db.js so I know it's not a MYSQL problem but for whatever reason it comes up blank in index.js. Thanks in advance for any help!
EDIT - I have module.exports = DB I just forgot to include it because I only included partial bits of the file. Importing works just fine for me because I'm using babel and type: module in my package.json. I couldn't tag node because it requires 1500 rep.
You forgot to export your module. Thus database should be undefined in your code, resulting in your issues.
class DB {
constructor() {
this.connection = this.initialize();
}
initialize() {
return mysql.createConnection({
host: process.env.DB_HOST,
user: process.env.DB_USER,
password: process.env.DB_PASSWORD,
database: process.env.DB_NAME,
});
selectAllFromProducts() {
this.initialize();
this.connection.query(`select * from ${process.env.DB_PRODUCTS_TABLE};`,
(err, results, fields) => {return results});
}
}
module.exports = DB;
Also importing is a little different in node.js
var DB = require("./db.js");
var express = require("express");
var cors = require("cors");
const database = new DB();
app.get("/", (req, res) => {
const data = database.selectAllFromProducts();
console.log(data); // Returns undefined
});
app.listen(process.env.PORT, () =>
console.log(`Listening on Port ${process.env.PORT}`)
);
Note: You should be able to use javascript modules in node.js versions greater than 13 (which is why your code may be working). Make sure your deployment server supports node.js 13 as well if you decide to use that syntax. More on javascript modules
Related
I have been following a tutorial on setting up REST APIs in Node, using Express for an app that accesses an existing MariaDB database. My version only needs to read data and I have the DB co-located with the Node application (same host).
My goal for this entry-level example is to just access the data, using static SQL, so I can see it rendered in the web page by the JSON pritifier.
[Next, I want to present the data in a table (EJS?). Later, when I can get that to work, I'll add form controls (React?) to let a user specify start and end date bounds for the SQL query. Finally I'll aim to render the data as a line graph (D3js).]
The tutorial runs the web server successfully (it returns 'OK' on the base URL), but when I go to URL/solarData it tries an async function to getMultiple rows from the DB, it responds:
Bind parameters must not contain undefined. To pass SQL NULL specify JS null TypeError: Bind parameters must not contain undefined. To pass SQL NULL specify JS null
at /SunnyData/solarViz/node_modules/mysql2/lib/connection.js:628:17
at Array.forEach (<anonymous>)
at Connection.execute (/SunnyData/solarViz/node_modules/mysql2/lib/connection.js:620:22)
at /SunnyData/solarViz/node_modules/mysql2/promise.js:120:11
at new Promise (<anonymous>)
at PromiseConnection.execute (/SunnyData/solarViz/node_modules/mysql2/promise.js:117:12)
at Object.query (/SunnyData/solarViz/services/db.js:6:40)
at processTicksAndRejections (internal/process/task_queues.js:95:5)
at async Object.getMultiple (/SunnyData/solarViz/services/solarData.js:7:16)
at async /SunnyData/solarViz/routes/solarData.js:8:14
app.js:61
./app.js
const express = require('express');
const app = express();
const port = process.env.PORT || 3800;
const solarDataRouter = require('./routes/solarData');
app.use(express.json());
app.use(
express.urlencoded({
extended: true,
})
);
app.get('/', (req, res) => {
res.json({'message': 'ok'});
})
app.use('/solarData', solarDataRouter);
/* Error handler middleware */
app.use((err, req, res, next) => {
const statusCode = err.statusCode || 500;
console.error(err.message, err.stack);
res.status(statusCode).json({'message': err.message});
return;
});
app.listen(port, () => {
console.log(`Example app listening at http://localhost:${port}`)
});
./routes/solarData.js
const express = require('express');
const router = express.Router();
const solarData = require('../services/solarData');
/* GET solar data. */
router.get('/', async function(req, res, next) {
try {
res.json(await solarData.getMultiple(req.query.page));
} catch (err) {
console.error(`Error while getting solar data `, err.message);
next(err);
}
});
module.exports = router;
./config.js
const env = process.env;
const config = {
db: {
host: env.SUNNY_HOST,
user: env.SUNNY_USER,
password: env.SUNNY_PW,
database: env.SUNNY_DB,
},
listPerPage: env.LIST_PER_PAGE,
};
module.exports = config;
./services/solarData.js
const db = require('./db');
const helper = require('../helper');
const config = require('../config');
async function getMultiple(page = 1){
const offset = helper.getOffset(page, config.listPerPage);
const rows = await db.query(
`SELECT * FROM DTP LIMIT ?,?`, [offset, config.listPerPage]
);
const data = helper.emptyOrRows(rows);
const meta = {page};
return {
data,
meta
}
}
module.exports.getMultiple = getMultiple;
./services/db.js
const mysql = require('mysql2/promise');
const config = require('../config');
async function query(sql, params) {
const connection = await mysql.createConnection(config.db);
const [results, ] = await connection.execute(sql, params);
return results;
}
module.exports = {
query
}
I've left out the ./helper.js
Everything runs fine until I direct the webpage to /solarData. At that point I get the Debug Console (vscode) mentioned up-front
Searching seems to point at a mysql2 shortcoming/bug but not at a practical solution
If you respond, please describe the 'bind' mechanism, as I'm not sure what's going on.
Hope I've put enough info in. Please ask if I need to add anything else.
The error says
Bind parameters must not contain undefined.
It means that in the file ./services/solarData.js on the line
const rows = await db.query(
`SELECT * FROM DTP LIMIT ?,?`, [offset, config.listPerPage]
);
Some of the 2 variables is undefined, you need to check offset and config.listPerPage to be defined.
Just use
console.log('offset: ' + offset)
console.log('listPerPage: ' + config.listPerPage)
and you will find out what is undefined in your case
I have a problem with the approach I use to connect to Mondo DB.
I use the following method:
import { Db, MongoClient } from "mongodb";
let cachedConnection: { client: MongoClient; db: Db } | null = null;
export async function connectToDatabase(mongoUri?: string, database?: string) {
if (!mongoUri) {
throw new Error(
"Please define the MONGO_URI environment variable inside .env.local"
);
}
if (!database) {
throw new Error(
"Please define the DATABASE environment variable inside .env.local"
);
}
if (cachedConnection) return cachedConnection;
cachedConnection = await MongoClient.connect(mongoUri, {
useNewUrlParser: true,
useUnifiedTopology: true,
}).then((client) => ({
client,
db: client.db(database),
}));
return cachedConnection!;
}
Everytime I need to connect to MongoDB I do as follows:
const { db } = await connectToDatabase(config.URI, config.USERS_DATABASE);
const myUniversity = await db
.collection(config.MY_COLLECTION)
.findOne({})
Everything seems ok, so what is the problem?
The problem is that the connections to my DB don't close after I use them. In fact I thought that my server is stateless so after every time i use my DB, the connections end. But it is not true! They stay alive, and after few hours of using my app mongo atlas sends me an email saying that the limit is exceeded.
As you can see in this screenshot, this chart is ever growing. That means that connections stay on and they accumulate. How do you think I can solve this problem?
Keep in mind that it uses cachedConnection only if I use the same connection. If I call a different API from the first one it creates another connection and it doesn't enter in if (cachedConnection) block, but it goes forward till the end.
You can try this simple demo which will allow you to use the same connection throughout the application in different modules. There are three modules: the index.js is the starter program, the dbaccess.js is where you have code to create and maintain a connection which can be used again and again, and a apis.js module where you use the database connection to retrieve data.
index.js:
const express = require('express');
const mongo = require('./dbaccess');
const apis = require('./apis');
const app = express();
const init = async () => {
await mongo.connect();
app.listen(3000);
apis(app, mongo);
};
init();
dbaccess.js:
const { MongoClient } = require('mongodb');
class Mongo {
constructor() {
this.client = new MongoClient("mongodb://127.0.0.1:27017/", {
useNewUrlParser: true,
useUnifiedTopology: true
});
}
async connect() {
await this.client.connect();
console.log('Connected to MongoDB server.');
this.db = this.client.db('test');
console.log('Database:', this.db.databaseName);
}
}
module.exports = new Mongo();
apis.js:
module.exports = function(app, mongo) {
app.get('/', function(req, res) {
mongo.db.collection('users').find().limit(1).toArray(function(err, result) {
res.send('Doc: ' + JSON.stringify(result));
});
});
}
Change the appropriate values in the url, database name and collection name before trying.
So I deployed my website portfolio with Heroku but my contact form (which uses nodemailer) is not working. It's weird because when I try it from my computer, I receive an email but I hear from others that it is not working on their end. This is the code of my index.js:
var express = require('express');
var router = express.Router();
var nodemailer = require('nodemailer');
var cors = require('cors');
const creds = require('./config');
var transport = {
host: 'smtp.gmail.com',
port: 465,
auth: {
user: creds.USER,
pass: creds.PASS
}
}
var transporter = nodemailer.createTransport(transport)
transporter.verify((error, success) => {
if (error) {
console.log(error);
} else {
console.log('Server is ready to take messages');
}
});
router.post('/send', (req, res, next) => {
var name = req.body.name
var email = req.body.email
var message = req.body.message
var content = ` name: ${name} \n email: ${email} \n message: ${message} `
var mail = {
from: name,
to: 'js5360#columbia.edu',
subject: 'New Message from Contact Form',
text: content
}
transporter.sendMail(mail, (err, data) => {
if (err) {
res.json({
status: 'fail'
})
} else {
res.json({
status: 'success'
})
}
})
})
const app = express()
app.use(cors())
app.use(express.json())
app.use('/', router)
app.listen(3002)
Here's the handler function I used:
constructor(props) {
super(props);
this.state = {
name: "",
email: "",
message: "",
}
}
handleSubmit(e){
e.preventDefault();
axios({
method: "POST",
url:"http://localhost:3002/send",
data: this.state
}).then((response)=>{
if (response.data.status === 'success'){
alert("Message Sent.");
this.resetForm()
}else if(response.data.status === 'fail'){
alert("Message failed to send.")
}
})
}
resetForm(){
this.setState({name: "", email: "", message: ""})
}
Previously when I was working on localhost, I had already enabled access to less secure apps so it was working fine locally.
Admittingly, I don't know much about express or nodemailer and followed the instructions outlined here: https://blog.mailtrap.io/react-contact-form/. I have a feeling that the url I am sending get/post requests is a local one, which makes prevents it from working on computers other than my own.
Could anyone provide some input into what I have to fix? Any help would be greatly appreciated:)
Try this,
https://accounts.google.com/b/0/DisplayUnlockCaptcha
I received an email by Google that my account was being accessed from the server location, if you do just tell Google not to block it.
This will allow machines to access your Gmail remotely.
Note:This will work for a short period of time.
I'm actually having this same issue right now but there are a few things that you might need to fix prior to getting to that point, the big one is environment variables.
Is your page deploying to heroku still despite being served on port 3002? Like your content is showing up after Heroku builds it? I had that error and if you're facing it you can solve it by replacing server port with process.env.PORT, which heroku automatically will assign internally during produciton. See the server file I've pasted below.
const port = process.env.PORT || 3000;
...
app.listen(port, () => {
console.log(`Server is up on port ${port}!`);
});
will take care of that.
Secondly, the when deployed the URL isn't going to be localhost anymore. it has to point to your domain suffixed by the api route axios.post('www.example.com/send', object)...
you can have that taken care of during the build by using dotenv environment variables ex:
let URI = process.env.NODE_ENV === 'development' ? process.env.REACT_APP_DEV_URI : process.env.REACT_APP_PROD_URI;
and having a .env file in your root directory
REACT_APP_DEV_URI=http://www.localhost:3000
REACT_APP_PROD_URI=https://www.example.com
then in your react client
axios.post(`${URI}/send-email`, data)
look up the dotenv npm module and using it to pull different environment variables based on if the app is in dev or production mode. via process.env.NODE_ENV
best practices is to .gitignore this file as it an expose credentials in public on github. Heroku will ignore it anyways, environment variables have to be set via the CLI, you can just copy and paste each on in one at a time and set with these commands or there is a page on heroku for adding this config. https://devcenter.heroku.com/articles/config-vars
same thing on the server side.
/**
* express.router() option? : https://stackoverflow.com/questions/61852261/nodemailer-not-working-on-heroku-deployment
*/
const express =
require('express'),
bodyParser = require('body-parser'),
nodemailer = require('nodemailer'),
cors = require('cors'), path = require('path'),
port = process.env.PORT || 3000;
require('dotenv').config();
let directory = process.env.NODE_ENV === 'development' ? 'public' : 'build',
publicPath = path.join(__dirname, '..', directory);
const app = express();
console.log(process.env.NODE_ENV)
app.use(cors());
app.use(express.static(publicPath));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));
app.get('*', (req, res) => {
res.sendFile(path.join(publicPath, 'index.html'));
});
app.post('/send-email', (req, res) => {
console.log('request: ', req.body)
let data = req.body;
let transporter = nodemailer.createTransport({
service: 'gmail',
port: 465,
auth: {
user: process.env.EMAIL,
pass: process.env.PASSWORD
}
});
let mailOptions = {
from: data.email,
to: process.env.EMAIL,
subject: `${data.subject}`,
html: `<p>${data.name}</p>
<p>${data.email}</p>
<p>${data.message}</p>`
};
// console.log('mailOptions are', mailOptions)
transporter.sendMail(mailOptions,[
(err, info) => {
if(err) {
res.send(err)
} else {
res.send(info.messageId)
}
transporter.close();
}]);
})
app.listen(port, () => {
console.log(`Server is up on port ${port}!`);
});
I'll keep you updated as to what I'm doing to get mine to work as well.
I was searching a similar issue. When I send contact mail from my local backend server port 3000, it worked fine. But after pushing to Heroku it didn't work. The issue was related to the .env file.
So by adding the ".env" codes directly to "Config Vars" in the settings panel of the Heroku dashboard, I was able to successfully send an email.
EMAIL_ID=your#email.com
PASSWORD=yourpassword
ie key: EMAIL-ID
value: your#email.com
etc.
All the best
I have hard time understanding why my code doesn't work. I am using node package mssql and want to have database pool connection initiation in separate file:
databaseConnection.js:
const sql = require("mssql/msnodesqlv8");
config = {
database: process.env.DB_NAME,
server: process.env.DB_SERVER,
driver: "msnodesqlv8",
options: {
trustedConnection: true
}
};
let pool = sql.connect(config);
module.exports = pool;
Then I have my express route file data.js
const express = require("express");
const router = express.Router();
const db = require("../configs/databaseConnection");
router.get("/dataList", async (req, res) => {
let allData = await db.request().query("select * from dataList");
console.log(allData);
res.render("dataList", { title: "Data list" });
});
module.exports = router;
However, when I start the server and go to the route I get error:
(node:13760) UnhandledPromiseRejectionWarning: TypeError: db.request is not a function
The thing is if I setup precisely as this example mssql documentation (where verything would be done in the route) it works. However, if database connection is in separate file it doesn't work.
I would appreciate any help understanding this
Regards,
Rokas
sql.connect returns a promise, so once we know that, we can either do a .then(result => ... or use await, for example:
If you want to store the db object at startup for later I'd suggest changing the line:
const db = require("../configs/databaseConnection");
to
let db = null;
require("../configs/databaseConnection").then(pool => {
db = pool;
});
How can i access the variable "knex1" from the below code from "knexfile.js" file into the the "db.js" file to check that whether the connection within "db.js" is connected or not ,thereby saying console message as "DB Connected"? ... But it says "TypeError: Cannot read property 'connect' of undefined" error when i run?
knexfile.js
var knex1 = {
development: {
client: 'mysql',
connection: {
host: 'localhost',
user: 'root',
password: 'password',
database: 'user_data',
}
},
};
module.exports = knex1;
db.js file
const mysql = require('mysql');
const db = require('../knexfile');
const NODE_ENV = 'development' ;
const knex = require('knex')((db)[NODE_ENV]);
const bookshelf = require('bookshelf')(knex);
db.connection.connect(function(err){
if(!err) {
console.log("Database is connected ... ");
}
else {
console.log("Error connecting database ... ");
}
});
let registerdata = bookshelf.Model.extend({
tableName: 'RegisterData'
});
module.exports = {
registerdata
};
First check your directory listing if your db.js and knexfile.js are in same folder like this
-db.js
-knexfile.js
then use const db = require('./knexfile');
if the db.js is inside another folder like this
-folder
-db.js
-knexfile.js
then use const db = require('../knexfile');
The ../ or ./ or ../../ is how you find your files.
Check out this link for more on how to handle es6 modules.
https://learnersbucket.com/tutorials/es6/es6-modules/