I'm doing a simple newsletter app in electron, I need to connect to my database, but if I use "require" to call mysql library it gives me "require is not defined", I tryed to use browsify but it didn't work, somebody can help me? (This script is in an HTML page)
<script>
document.getElementById("btn").addEventListener("click", () => {
var mysql = require (['./node_modules/mysql']);
var connection = mysql.createConnection({
host: 'localhost',
user: 'user',
password: 'password',
database: 'db',
});
$sql = 'SELECT `id`,`first_name`,`last_name`,`email` FROM `subscribers`';
connection.query($sql, function (error, results, fields) {
if (error) throw error;
console.log(results);
$('#resultDiv').text(results[0].email);
});
connection.end();
})
</script>
Require is not part of the standard JS API, it is part of the Node API. There is a great writeup here. The renderer process in electron, where the HTML is rendered, does not have access to the node API directly. You can setup a framework like Angular or React which gives you more more robust development environment, or you can use the Node API in the main process to fetch the data for you. You can send information back and forth using IPC calls to allow the HTML page to signal to the main process that information is needed. The docs here do a good job showing how this is done.
I think you'd be more successful however using a web development framework rather than using IPC calls for this purpose.
Related
When I pass the data from node server to front-end (angular 9), I faced the problem.
I made the server side using node and called data from google sheet api.
I tried to get the data from node server to angular and searched on google, but I couldn't find the result.
Here is my code of node server for calling data from googlesheet.
const doc = new GoogleSpreadsheet('1w0aEvmo8H-PPMQEaYWEfN8QSoeGgAKIb9gA0fr4V9VM');
async function accessSpreadSheet() {
await doc.useServiceAccountAuth({
client_email: creds.client_email,
private_key: creds.private_key,
});
await doc.loadInfo(); // loads document properties and worksheets
const sheet = doc.sheetsByIndex[0]; // or use doc.sheetsById[id]
console.log(sheet.title);
console.log(sheet.rowCount);
}
accessSpreadSheet();
In this case, I am not sure how can I pass data of server to angular front-end?
I followed to lots of stackoverflows, but couldn't get them.
Bellow links were I followed.
How do I pass node.js server variables into my angular/html view?
How to send JSON data from node to angular 4
send data from node.js to angular with get()
Please let me know how can I get the data from server into my frontend?
Thanks
If you are using node, the simplest way would be to create an express js api and return the information in an endpoint, though i recommend you learn some basic concepts about APIs and client\server http communication before you start your implementation
I have a front-end website created as Angular project. (using node.js) I have created a "server.ts" file and connected to the my DB succesfully. Now I want to get data from my database and print some on dashboard. How can I get data ?
var mysql = require('mysql');
var con = mysql.createConnection({
host: "myhost",
user: "myusername",
password: "mypassword"
});
con.connect(function(err){
if (err) throw err;
console.log("Connected!");
});
You can't get data from the database in an Angular app. Angular is a front-end framework, it means that you angular application will be downloaded and executed in the user's browser.
To access data from the database that is in the server side, you need a back-end application. You could do it from a node.js application with help of a framework like mysqljs.
There is an example in this video
You will need to create some sort of api for your front-end application to communicate with the backend server. A common option for this is Express. This involves quite a lot of code, so if you want specific help I suggest putting together a stackblitz, alternatively you may be interested in the following example:
https://morioh.com/p/33d0377536a6/angular7-crud-with-nodejs-and-mysql-example
If you want a more complete solution, you could also look into implementing a tooling system such as Prisma
from lib README on Github:
var mysql = require('mysql');
var connection = mysql.createConnection({
host : 'localhost',
user : 'me',
password : 'secret',
database : 'my_db'
});
connection.connect();
connection.query('SELECT 1 + 1 AS solution', function (error, results, fields) {
if (error) throw error;
console.log('The solution is: ', results[0].solution);
});
connection.end();
you can use .query() for example to trigger requests and fetch data.
I'm a beginner to Node.js and I'm currently building a Node.js program that accesses and queries a Microsoft Azure SQL database with the "tedious" module (see code below) and puts the data onto a html webpage. I want to run this code in a browser so I used browserify to bundle the modules together. However, when this code is run in Google Chrome, the following error is returned: require is not defined. Is there a fix? Is it even possible to use the tedious module in Chrome? If it isn't possible, do I need to use an intermediate server between the Node.js application and the webpage?
var Connection = require('tedious').Connection;
var config = {
userName: 'hackmatch',
password: 'hackvalley123!',
server: 'hackmatch.database.windows.net',
options: {encrypt: true, database: 'AdventureWorks'}
};
var connection = new Connection(config);
connection.on('connect', function(err) {
// If no error, then good to proceed.
console.log("Connected");
});
var Request = require('tedious').Request;
var TYPES = require('tedious').TYPES;
Thanks in advance for your help! :)
No. This module can only be used in Node.
tedious depends on the node.js net module to make a connection to the database server. This module has no equivalent on the browser, as web pages cannot make arbitrary network connections.
Even if it were possible to use this module in the browser, it'd be a terrible idea. You'd be allowing anyone on your web site to connect directly to your SQL server and run SQL queries. This can only end badly.
firstly sorry for not standard English. : D
I have a chat application using nodejs, expresss finished running on port 3000. So I want to embed in website application clients, then how?
I had to use ajax load, but can not be:
jQuery.ajax({
type:"GET",
url:"http://localhost:3000/client/",
success: function (data){
jQuery('body').append(data);
}
});
Since you are using socket.io at server side then you can get its reference at the client using below line (jquery required):
$.getScript(host+'socket.io/socket.io.js', function()
{
var clientSocket = io.connect(host);
// ... do other stuff with your socket
});
Where host is your server host name e.g. http://192.168.1.5:3000/ where your nodejs application is deployed.
For more information see here for more client - server communication exposed events.
try the example from http://book.mixu.net/node/ch3.html (it uses long-polling) once done with it use socket.io
I am using mongodb-native-driver in express.js app. I have around 6 collections in the database, so I have created 6 js files with each having a collection as a javascript object (e.g function collection(){}) and the prototypes functions handling all the manipulation on those collections. I thought this would be a good architecture.
But the problem I am having is how to connect to the database? Should I create a connection in each of this files and use them? I think that would be an overkill as the connect in mongodb-native-driver creates a pool of connections and having several of them would not be justified.
So how do I create a single connection pool and use it in all the collections.js files? I want to have the connection like its implemented in mongoose. Let me know if any of my thought process in architecture of the app is wrong.
Using Mongoose would solve these problems, but I have read in several places thats it slower than native-driver and also I would prefer a schema-less models.
Edit: I created a module out of models. Each collection was in a file and it took the database as an argument. Now in the index.js file I called the database connection and kept a variable db after I got the database from the connection. (I used the auto-reconnect feature to make sure that the connection wasn't lost). In the same index.js file I exported each of the collections like this
exports.model1 = require('./model1').(db)
exprorts.model2 = require('./model2').(db)
This ensured that the database part was handled in just one module and the app would just call function that each model.js file exported like save(), fincdbyid() etc (whatever you do in the function is upto you to implement).
how to connect to the database?
In order to connect using the MongoDB native driver you need to do something like the following:
var util = require('util');
var mongodb = require('mongodb');
var client = mongodb.MongoClient;
var auth = {
user: 'username',
pass: 'password',
host: 'hostname',
port: 1337,
name: 'databaseName'
};
var uri = util.format('mongodb://%s:%s#%s:%d/%s',
auth.user, auth.pass, auth.host, auth.port, auth.name);
/** Connect to the Mongo database at the URI using the client */
client.connect(uri, { auto_reconnect: true }, function (err, database) {
if (err) throw err;
else if (!database) console.log('Unknown error connecting to database');
else {
console.log('Connected to MongoDB database server at:');
console.log('\n\t%s\n', uri);
// Create or access collections, etc here using the database object
}
});
A basic connection is setup like this. This is all I can give you going on just the basic description of what you want. Post up some code you've got so far to get more specific help.
Should I create a connection in each of this files and use them?
No.
So how do I create a single connection pool and use it in all the collections.js files?
You can create a single file with code like the above, lets call it dbmanager.js connecting to the database. Export functions like createUser, deleteUser, etc. which operate on your database, then export functionality like so:
module.exports = {
createUser: function () { ; },
deleteUser: function () { ; }
};
which you could then require from another file like so:
var dbman = require('./dbmanager');
dbman.createUser(userData); // using connection established in `dbmanager.js`
EDIT: Because we're dealing with JavaScript and a single thread, the native driver indeed automatically handles connection pooling for you. You can look for this in the StackOverflow links below for more confirmation of this. The OP does state this in the question as well. This means that client.connect should be called only once by an instance of your server. After the database object is successfully retrieved from a call to client.connect, that database object should be reused throughout the entire instance of your app. This is easily accomplished by using the module pattern that Node.JS provides.
My suggestion is to create a module or set of modules which serves as a single point of contact for interacting with the database. In my apps I usually have a single module which depends on the native driver, calling require('mongodb'). All other modules in my app will not directly access the database, but instead all manipulations must be coordinated by this database module.
This encapsulates all of the code dealing with the native driver into a single module or set of modules. The OP seems to think there is a problem with the simple code example I've posted, describing a problem with a "single large closure" in my example. This is all pretty basic stuff, so I'm adding clarification as to the basic architecture at work here, but I still do not feel the need to change any code.
The OP also seems to think that multiple connections could possibly be made here. This is not possible with this setup. If you created a module like I suggest above then the first time require('./dbmanager') is called it will execute the code in the file dbmanager.js and return the module.exports object. The exports object is cached and is also returned on each subsequent call to require('./dbmanager'), however, the code in dbmanager.js will only be executed the first require.
If you don't want to create a module like this then the other option would be to export only the database passed to the callback for client.connect and use it directly in different places throughout your app. I recommend against this however, regardless of the OPs concerns.
Similar, possibly duplicate Stackoverflow questions, among others:
How to manage mongodb connections in nodejs webapp
Node.JS and MongoDB, reusing the DB object
Node.JS - What is the right way to deal with MongoDB connections
As accepted answer says - you should create only one connection for all incoming requests and reuse it, but answer is missing solution, that will create and cache connection. I wrote express middleware to achieve this - express-mongo-db. At first sight this task is trivial, and most people use this kind of code:
var db;
function createConnection(req, res, next) {
if (db) { req.db = db; next(); }
client.connect(uri, { auto_reconnect: true }, function (err, database) {
req.db = db = databse;
next();
});
}
app.use(createConnection);
But this code lead you to connection-leak, when multiple request arrives at the same time, and db is undefined. express-mongo-db solving this by holding incoming clients and calling connect only once, when module is required (not when first request arrives).
Hope you find it useful.
I just thought I would add in my own method of MongoDB connection for others interested or having problems with different methods
This method assumes you don't need authentication(I use this on localhost)
Authentication is still easy to implement
var MongoClient = require('mongodb').MongoClient;
var Server = require('mongodb').Server;
var client = new MongoClient(new Server('localhost',27017,{
socketOptions: {connectTimeoutMS: 500},
poolSize:5,
auto_reconnect:true
}, {
numberOfRetries:3,
retryMilliseconds: 500
}));
client.open(function(err, client) {
if(err) {
console.log("Connection Failed Via Client Object.");
} else {
var db = client.db("theDbName");
if(db) {
console.log("Connected Via Client Object . . .");
db.logout(function(err,result) {
if(!err) {
console.log("Logged out successfully");
}
client.close();
console.log("Connection closed");
});
}
}
});
Credit goes to Brad Davley which goes over this method in his book (page 231-232)