Develop Reference

handling request errors in node

I am using request to access data from an api. sometimes, when the api Url is down, node throws error and shuts down with the following error
`at ClientRequest.emit (events.js:315:20)`
`at TLSSocket.socketErrorListener (_http_client.js:426:9)`
`at TLSSocket.emit (events.js:315:20)`
`at emitErrorNT (internal/streams/destroy.js:92:8)`
`at processTicksAndRejections (internal/process/task_queues.js:84:21)
errno: 'ENOTFOUND',
code: 'ENOTFOUND',
syscall: 'getaddrinfo',
hostname: APIURL
is there any way to handle this and prevent node from exiting?
my code is
const JSONdata= ()=>{
request({url:API_URL2,json:true},(error,response,body)=>{
const data=[]
var jsondata=body
data.push(jsondata)
const data2=JSON.stringify(data)
fs.writeFile('sample.txt',data2,(err) => { if(error){console.log(error} })})

having a try-catch will prevent failure or system crash, also you get process.uncaughtException() to do something when the system crashes
check below link for more details
https://nodejs.org/api/process.html#process_event_uncaughtexception

Heroku: Javascript/MySQL project crashing on request

I have a Heroku API written in JavaScript that reads data from a MySQL database. It previously worked, but now every time I send a request to the API, I get this error:
2020-06-17T18:37:13.493711+00:00 app[web.1]: > my_api#0.0.0 start /app
2020-06-17T18:37:13.493712+00:00 app[web.1]: > node ./bin/www
2020-06-17T18:37:13.493712+00:00 app[web.1]:
2020-06-17T18:37:14.977800+00:00 heroku[web.1]: State changed from starting to up
2020-06-17T18:38:40.255982+00:00 app[web.1]: /app/node_modules/mysql2/lib/connection.js:149
2020-06-17T18:38:40.256022+00:00 app[web.1]: err.fatal = true;
2020-06-17T18:38:40.256023+00:00 app[web.1]: ^
2020-06-17T18:38:40.256023+00:00 app[web.1]:
2020-06-17T18:38:40.256026+00:00 app[web.1]: TypeError: Cannot create property 'fatal' on string 'SOCKS: Authentication failed'
2020-06-17T18:38:40.256027+00:00 app[web.1]: at Connection._handleFatalError (/app/node_modules/mysql2/lib/connection.js:149:15)
2020-06-17T18:38:40.256027+00:00 app[web.1]: at Connection._handleNetworkError (/app/node_modules/mysql2/lib/connection.js:169:10)
2020-06-17T18:38:40.256027+00:00 app[web.1]: at SocksConnection.emit (events.js:315:20)
2020-06-17T18:38:40.256029+00:00 app[web.1]: at /app/node_modules/socksjs/socks.js:146:18
2020-06-17T18:38:40.256029+00:00 app[web.1]: at Socket.dataReady (/app/node_modules/socksjs/socks.js:93:13)
2020-06-17T18:38:40.256029+00:00 app[web.1]: at Socket.emit (events.js:315:20)
2020-06-17T18:38:40.256030+00:00 app[web.1]: at emitReadable_ (_stream_readable.js:556:12)
2020-06-17T18:38:40.256030+00:00 app[web.1]: at processTicksAndRejections (internal/process/task_queues.js:83:21)
2020-06-17T18:38:40.263200+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2020-06-17T18:38:40.263391+00:00 app[web.1]: npm ERR! errno 1
2020-06-17T18:38:40.264251+00:00 app[web.1]: npm ERR! my_api#0.0.0 start: `node ./bin/www`
2020-06-17T18:38:40.264354+00:00 app[web.1]: npm ERR! Exit status 1
2020-06-17T18:38:40.264471+00:00 app[web.1]: npm ERR!
The code in question looks like this:
function new_db_connection() {
var sockConn = new SocksConnection(remote_options, sock_options);
var dbConnection = mysql.createConnection({
user: 'myusername',
database: 'mydatabase',
password: 'mypassword',
stream: sockConn
});
return [sockConn, dbConnection];
};
router.get('/myrequest', function(req, res, next) {
new_conn = new_db_connection();
dbConnection = new_conn[1];
sockConn = new_conn[0];
dbConnection.query('SELECT * from mytable', function(error, results, fields) {
if (error) {
res.send(JSON.stringify({
"status": 500,
"error": error,
"response": null
}));
//If there is error, we send the error in the error section with 500 status
} else {
res.send(JSON.stringify({
"status": 200,
"error": null,
"response": results
}));
//If there is no error, all is good and response is 200OK.
}
sockConn.dispose();
});
dbConnection.end()
});
I saw a similar question asked on here and the solution was to close the connection, but I do close the connection after each request, so I don't know where the issue is.
All help appreciated.

Try to change this
sockConn.dispose();
});
dbConnection.end()
});
in this
sockConn.dispose();
dbConnection.end()
});
});
Edit: reading better the error, it could be the problem is some where else.
Looking at the string 'SOCKS: Authentication failed', could it be that you or the SocksConnection remote endpoint changed something in the authentication?
Hope this helps.

You should take a look at the answer provided by #daniele Rici you need to end your connection properly; however, fixing this will not solve your initial question.
The issue is not with your code. Your issue is with connection configuration.
'fatal' on string 'SOCKS: Authentication failed'
Means there was an error with authentication.
var sockConn = new SocksConnection(remote_options, sock_options);
under the assumention you are using ther npm package socksjs from https://openbase.io/js/socksjs
It is documented that the correct way to initialize a sockjs connection is by doing the following:
var sock = new SocksConnection(remote_options, sock_options);
var sock = SocksConnection.connect(remote_options, sock_options, connect_handler);

MongoDb Connection Error when using Mongoose

I did not have a problem connecting to Atlas previously from my wifi at home. But I have issues at Starbucks. I have now switched to google fiber and I am getting this error.
at Pool.<anonymous> (/Users/j/Desktop/projects/templateApp/node_modules/mongodb-core/lib/topologies/server.js:431:11)
at Pool.emit (events.js:182:13)
at connect (/Users/j/Desktop/projects/templateApp/node_modules/mongodb-core/lib/connection/pool.js:557:14)
at callback (/Users/j/Desktop/projects/templateApp/node_modules/mongodb-core/lib/connection/connect.js:109:5)
at runCommand (/Users/j/Desktop/projects/templateApp/node_modules/mongodb-core/lib/connection/connect.js:129:7)
at Connection.errorHandler (/Users/j/Desktop/projects/templateApp/node_modules/mongodb-core/lib/connection/connect.js:321:5)
at Object.onceWrapper (events.js:273:13)
at Connection.emit (events.js:182:13)
at TLSSocket.<anonymous> (/Users/j/Desktop/projects/templateApp/node_modules/mongodb-core/lib/connection/connection.js:350:12)
at Object.onceWrapper (events.js:273:13)
at TLSSocket.emit (events.js:182:13)
at _handle.close (net.js:596:12)
at TCP.done [as _onclose] (_tls_wrap.js:383:7)
name: 'MongoNetworkError',
errorLabels: [ 'TransientTransactionError' ],```
I have checked my strings and they are correct.
My connection code is:
```mongoose.connect(process.env.dataBaseConnection, {
dbName: process.env.dataBaseName,
useFindAndModify: false,
useNewUrlParser: true
});```

The issue was that I needed to white list my new ip address.

Postresql not connecting to heroku

im using heroku to host my site however it keeps spitting out the same error which is
2018-05-06T19:28:52.212104+00:00 app[web.1]:AssertionError [ERR_ASSERTION]: false == true
2018-05-06T19:28:52.212106+00:00 app[web.1]:at Object.exports.connect (_tls_wrap.js:1036:3)
2018-05-06T19:28:52.212107+00:00 app[web.1]: at Socket. (/app/node_modules/pg/lib/connection.js:94:23)
2018-05-06T19:28:52.212109+00:00 app[web.1]:at Object.onceWrapper (events.js:315:30)
2018-05-06T19:28:52.212110+00:00 app[web.1]:at emitOne (events.js:116:13)
2018-05-06T19:28:52.212112+00:00 app[web.1]: at Socket.emit (events.js:211:7)
2018-05-06T19:28:52.212113+00:00 app[web.1]:at addChunk (_stream_readable.js:263:12)
2018-05-06T19:28:52.212115+00:00 app[web.1]:at readableAddChunk (_stream_readable.js:250:11)
2018-05-06T19:28:52.212116+00:00 app[web.1]:at Socket.Readable.push (_stream_readable.js:208:10)
2018-05-06T19:28:52.212118+00:00 app[web.1]: at TCP.onread >>(net.js:607:20)
this is how im connecting (taken straight off of herokus website)
const { Client } = require("pg");
const router = express.Router();
const pool = new Client({
connectionString: process.env.DATABASE_URL,
ssl: true,
});
pool.connect();
I found out what the error was:
the error was that i did not have a db create. i decided to use elephantSQL and from their i connected to elephantSQL with pgadmin and recreated my database. it works perfect now
to see how this works see : https://www.elephantsql.com/docs/pgadmin.html
im more than happy to answer some questions

OK, this isn't really a solution but it might help you out. This happens to me on node 8 (and 10) but when I downgraded to node 7 it seems to work fine. I'll be watching this post to see if someone comes up with a better fix.

Node.js: Any error crashes Heroku server

I have a Node.js app to do some simple processing, however, every time there's an error, the server crashes.
2011-12-19T19:27:49+00:00 app[web.1]: node.js:134
2011-12-19T19:27:49+00:00 app[web.1]: throw e; // process.nextTick error, or 'error' event on first tick
2011-12-19T19:27:49+00:00 app[web.1]: ^
2011-12-19T19:27:49+00:00 app[web.1]: TypeError: Object { customer_id: 4eef8ddb74019b9d4f00001d,
2011-12-19T19:27:49+00:00 app[web.1]: date: Mon, 19 Dec 2011 19:27:36 GMT,
2011-12-19T19:27:49+00:00 app[web.1]: callsid: '123',
2011-12-19T19:27:49+00:00 app[web.1]: _id: 4eef902887e9770100000008 } has no method 'save'
2011-12-19T19:27:49+00:00 app[web.1]: at Promise.<anonymous> (/app/src/call.js:137:24)
2011-12-19T19:27:49+00:00 app[web.1]: at Promise.<anonymous> (/app/node_modules/mongoose/lib/promise.js:120:8)
2011-12-19T19:27:49+00:00 app[web.1]: at Promise.<anonymous> (events.js:64:17)
2011-12-19T19:27:49+00:00 app[web.1]: at Promise.emit (/app/node_modules/mongoose/lib/promise.js:59:38)
2011-12-19T19:27:49+00:00 app[web.1]: at Promise.complete (/app/node_modules/mongoose/lib/promise.js:70:20)
2011-12-19T19:27:49+00:00 app[web.1]: at /app/node_modules/mongoose/lib/query.js:738:28
2011-12-19T19:27:49+00:00 app[web.1]: at model.init (/app/node_modules/mongoose/lib/model.js:181:36)
2011-12-19T19:27:49+00:00 app[web.1]: at cb (/app/node_modules/mongoose/lib/query.js:736:14)
2011-12-19T19:27:49+00:00 app[web.1]: at Array.<anonymous> (/app/node_modules/mongoose/lib/utils.js:394:16)
2011-12-19T19:27:49+00:00 app[web.1]: at model.<anonymous> (/app/node_modules/mongoose/lib/document.js:181:5)
How do I protect from such errors? For example, when I call a variable that doesn't exist, the server crashes. I understand the error but sometimes I only notice the error when deployed and the server crashes.

You can make sure your script doesn't stop by catching the 'uncaughtException' with process.on('uncaughtException', callback), like so:
process.on('uncaughtException', function (exception) {
// handle or ignore error
console.log(exception);
});
setInterval(function() {
console.log('tick, even after error');
}, 1000);
a += 1;