I am trying to read from a slave node but I get the following error.
MongoError: not master
at Function.MongoError.create (node_modules/mongodb-core/lib/error.js:31:11)
at node_modules/mongodb-core/lib/topologies/server.js:777:66
at Callbacks.emit (node_modules/mongodb-core/lib/topologies/server.js:95:3)
at null.messageHandler (node_modules/mongodb-core/lib/topologies/server.js:249:23)
at Socket.<anonymous> (node_modules/mongodb-core/lib/connection/connection.js:265:22)
at emitOne (events.js:78:13)
at Socket.emit (events.js:170:7)
at readableAddChunk (_stream_readable.js:147:16)
at Socket.Readable.push (_stream_readable.js:111:10)
at TCP.onread (net.js:524:20)
Here is my code
var MongoClient = require('mongodb').MongoClient
MongoClient.connect('mongodb://slave.example.com/?slaveOk=true', {slaveOk: true}, (err, db) => {
if (err) { throw err }
d = db.db('order', {server: {slaveOk: true}})
d.eval('rs.slaveOk(); 1', (err, data) => {
if (err) { throw err }
console.log(data);
})
})
I am providing the complete list of hosts in the connection string because the node that is running this query only has access to the secondary MongoDB nodes.
When using the command line interface I am able to make queries as long as I run rs.slaveOk() before executing my query.
you can simply using below code
var collection1 = db.collection(currentCollection,{readPreference:'secondaryPreferred'});
for more details check Scaling Read Query Load
Related
I have been new to MongoDB and I am trying to connect mongodb using nodejs application.
whenever i try to run the nodejs file an error is being raised.
MongoError: Unsupported OP_QUERY command: insert. The client driver may require an upgrade. For more details see https://dochub.mongodb.org/core/legacy-opcode-removal
const MongoClient = require('mongodb').MongoClient;
const assert = require('assert');
const url = 'mongodb://localhost:27017';
const dbName = 'conFusion';
const client = new MongoClient(url);
client.connect()
.then((client) => {
console.log('Connected correctly to server');
const db = client.db(dbName);
const collection = db.collection('dishes');
collection.insertOne({name: "Uthapizza", description: "test"})
.then((result) => {
console.log('Insert Document:\n', result.ops);
return collection.find({}).toArray();
})
.then((docs) => {
console.log('Found Documents:\n', docs);
return collection.deleteMany({});
})
.then((result) => {
console.log('Deleted Documents:\n', result);
return client.close();
})
.catch((err) => console.log(err));
})
I have been using mongoDB latest version 6.0 and i am not able to perform the insertion operation using my node application.
Connected correctly to server
MongoError: Unsupported OP_QUERY command: insert. The client driver may require an upgrade. For more details see https://dochub.mongodb.org/core/legacy-opcode-removal
at C:\Users\koushik\OneDrive\Desktop\Nodejs\node-mongo\node_modules\mongodb-core\lib\connection\pool.js:593:63
at authenticateStragglers (C:\Users\koushik\OneDrive\Desktop\Nodejs\node-mongo\node_modules\mongodb-core\lib\connection\pool.js:516:16)
at Connection.messageHandler (C:\Users\koushik\OneDrive\Desktop\Nodejs\node-mongo\node_modules\mongodb-core\lib\connection\pool.js:552:5)
at emitMessageHandler (C:\Users\koushik\OneDrive\Desktop\Nodejs\node-mongo\node_modules\mongodb-core\lib\connection\connection.js:309:10)
at Socket.<anonymous> (C:\Users\koushik\OneDrive\Desktop\Nodejs\node-mongo\node_modules\mongodb-core\lib\connection\connection.js:452:17)
at Socket.emit (node:events:527:28)
at addChunk (node:internal/streams/readable:315:12)
at readableAddChunk (node:internal/streams/readable:289:9)
at Socket.Readable.push (node:internal/streams/readable:228:10)
at TCP.onStreamRead (node:internal/stream_base_commons:190:23) {
ok: 0,
errmsg: 'Unsupported OP_QUERY command: insert. The client driver may require an upgrade. For more details see https://dochub.mongodb.org/core/legacy-opcode-removal',
code: 352,
codeName: 'UnsupportedOpQueryCommand'
}
Please Help Me with this Problem and Please Mention The Solution. What Should I do To perform the operation as it is not working and op_query is deprecated in latest version.
The error says what you need to do (ie use latest mongo node driver). Latest servers stopped supporting legacy OP_INSERT/OP_QUERY wire protocols
I am using a postgres database for my express web server.
I am using the 'pg' library to execute queries on this database.
Here is my connection method :
const db = new Client({
user: 'xxx',
host: 'xxx',
database: 'xxx',
password: 'xxx',
port: xxx,
})
db.connect(err => {
if (err) {
console.error('connection error', err.stack)
} else {
console.log('connected')
}
Then to execute a request I do this:
db.query(MY_REQUEST, function (err, data) {
if (err) throw err;
res.render('hello/world', {
title: 'Hello',
data: data.rows
});
});`
It all works perfectly. But after several minutes without using my website, my connection to the db times out, and I get the following error:
node:events:355
throw er; // Unhandled 'error' event
^
Error: Connection terminated unexpectedly
at Connection.<anonymous> (/usr/src/app/node_modules/pg/lib/client.js:132:73)
at Object.onceWrapper (node:events:484:28)
at Connection.emit (node:events:378:20)
at Socket.<anonymous> (/usr/src/app/node_modules/pg/lib/connection.js:58:12)
at Socket.emit (node:events:378:20)
at TCP.<anonymous> (node:net:665:12)
Emitted 'error' event on Client instance at:
at Client._handleErrorEvent (/usr/src/app/node_modules/pg/lib/client.js:319:10)
at Connection.<anonymous> (/usr/src/app/node_modules/pg/lib/client.js:149:16)
at Object.onceWrapper (node:events:484:28)
[... lines matching original stack trace ...]
at TCP.<anonymous> (node:net:665:12)
How could I do to reconnect automatically when the connection is cut or when a request fails?
You should attach an error-handler in order to prevent the unhandled error crashing your app. It's as simple as:
db.on('error', e => {
console.error('DB error', e);
});
As to why the error happens we need more details, looks like it could be a connection reset due to idle-timeout?
You can create a function to control if you're connected to database or not, before you continue with your main function.
Create a function for controlling database connection status, reconnecting etc. and before you run a database related function, first start that middle function and wait for result, after that you can continue using database again.
If you want(which should be prefered way mostly), create that middle function as an async function and return a promise, when using that function wait for that function.
i am connecting mongodb using the mongodb client in my app.
'app.js' file.
var MongoClient = require('mongodb').MongoClient
MongoClient.connect('mongodb://localhost:27017/animals', function (err, db) {
if (err) throw err
// db.collection('mammals').find().toArray(function (err, result) {
// if (err) throw err
// console.log(result)
// })
})
the issue is:
(node:16348) DeprecationWarning: current URL string parser is
deprecated, and will be removed in a future version. To use the new
parser, pass option { useNewUrlParser: true } to MongoClient.connect.
/home/amarjeet/Desktop/node2/node_modules/mongodb/lib/operations/mongo_client_ops.js:474
throw err;
^
MongoNetworkError: failed to connect to server [localhost:27017] on
first connect [MongoNetworkError: connect ECONNREFUSED 127.0.0.1:27017]
at Pool.<anonymous> (/home/amarjeet/Desktop/node2/node_modules/mongodb-
core/lib/topologies/server.js:564:11)
at Pool.emit (events.js:188:13)
at Connection.<anonymous>
(/home/amarjeet/Desktop/node2/node_modules/mongodb-core/lib/connection/pool.js:317:12)
at Object.onceWrapper (events.js:276:13)
at Connection.emit (events.js:188:13)
at Socket.<anonymous> (/home/ amarjeet/Desktop/node2/node_modules/mongodb-core/lib/connection/connection.js:246:50)
at Object.onceWrapper (events.js:276:13)
at Socket.emit (events.js:188:13)
at emitErrorNT (internal/streams/destroy.js:82:8)
at emitErrorAndCloseNT (internal/streams/destroy.js:50:3)
[nodemon] app crashed - waiting for file changes before starting...
so this is the issue is shown on terminal and i have no idea how to fix it!
just add {useNewUrlParser: true } in connection
var MongoClient = require('mongodb').MongoClient
MongoClient.connect('mongodb://localhost:27017/animals', {useNewUrlParser: true }, function (err, db) {
if (err) throw err
// db.collection('mammals').find().toArray(function (err, result) {
// if (err) throw err
// console.log(result)
// })
})
You have to install MongoDB database server first in your system and start it.
if already installed:
check whether server is in start state. and Try connecting with mongo shell
and if server is also in start state:
than just put {useNewUrlParser: true } as mentioned by the #Vaghani Janak
UPDATE/SOLVED ... the problem was that pgpass plugin was looking for $HOME/.pgpass, and $HOME wasn't defined on lambda, causing failure of join(undefined, '.pgpass'). Not really worth crediting myself with an answer for that ....
I have the following test code in a lambda handler (compiled from typescript):
const db = new Pool()
const {rows} = await db.query('select 1 as x')
console.log('rows', JSON.stringify(rows))
The connection is created via PGHOST PGPORT PGUSER PGDATABASE in the environment. I know the configuration is "almost right" because the first time I tried it I got:
{"errorMessage":"error: no pg_hba.conf entry for host \"10.1.1.249\",
user \"foo\", database \"bar\", SSL off\n at
Connection.parseE (/var/task/handler.js:9209:11)\n at
Connection.parseMessage (/var/task/handler.js:9034:19)\n at
Socket. (/var/task/handler.js:8777:22)\n at emitOne
(events.js:96:13)\n at Socket.emit (events.js:188:7)\n at
readableAddChunk (_stream_readable.js:176:18)\n at
Socket.Readable.push (_stream_readable.js:134:10)\n at TCP.onread
(net.js:547:20)"}
That seemed hopeful. I changed the postgres config to allow from the subnet, and tried again. However, now I get:
2018-02-06 18:14:21.183 (-05:00) 76761ca5-0b93-11e8-8783-a74d098c9f4a select
2018-02-06 18:14:21.202 (-05:00) 76761ca5-0b93-11e8-8783-a74d098c9f4a TypeError: Path must be a string. Received undefined
at assertPath (path.js:7:11)
at Object.join (path.js:1211:7)
at Object.module.exports.getFileName (/var/task/handler.js:32434:16)
at module.exports (/var/task/handler.js:32355:23)
at Connection.<anonymous> (/var/task/handler.js:31255:9)
at emitOne (events.js:96:13)
at Connection.emit (events.js:188:7)
at Socket.<anonymous> (/var/task/handler.js:8781:12)
at emitOne (events.js:96:13)
at Socket.emit (events.js:188:7)
END RequestId: 76761ca5-0b93-11e8-8783-a74d098c9f4a
What is going on? It seemed as if it had got to the database and connected the first time... Now it fails on the query. Is there some option I should be using?
First, you are not calling pool.connect to acquire a client from the pool.
Second, the current Node.js runtime 6.10 on AWS Lambda does not support async functions. (Unless you transpile your code down to ES5 using Babel directly or some other boilerplate that uses Babel such as es2017-lambda-boilerplate)
Having said that, you'll have to use either callbacks or promises (then/catch). For example:
const {Pool} = require("pg");
const db = new Pool({
host: "localhost",
user: "database-user",
// ... rest of config options
});
db.connect((err, client, release) => {
if (err) {
console.error("Error acquiring client.", err.stack);
} else {
client.query("SELECT 1 AS x", (err, result) => {
release();
if (err) {
console.error("Error executing query.", err.stack);
} else {
console.log(result.rows);
}
})
}
})
I'm trying to connect a Node.js app with a PostgreSQL server. It seems that no matter what I use, I end up with the same error:
bundle.js:16177 ERROR: TypeError: net.Stream is not a constructor
at new Connection (bundle.js:10133)
at new Client (bundle.js:9704)
at Object.create (bundle.js:11308)
at Pool._createResource (bundle.js:510)
at Pool.dispense [as _dispense] (bundle.js:498)
at Pool.acquire (bundle.js:573)
at Pool.pool.connect (bundle.js:11359)
at PG.connect (bundle.js:10876)
at bundle.js:1642
At first I was declaring a new pg.Client() like the example in the documentation here, but got the above error discovered that might be a bad idea according to this stack overflow post.
I tried using pg.connect():
var pg = require('pg'); //postgresql dependency
var connectionString = "postgres://postgres:thisissuchagoodpassword#PostgreSQL/localhost:5432/Milestone1DB"
console.log("Initiating...");
//var connectionString = "postgres://postgres:thisissuchagoodpassword#PostgreSQL9.6/localhost:5432/Milestone1DB";
//var client = new pg.Client();
//connect to the database
console.log("Attempting to connect to the database");
pg.connect(function (err, client, done)
{
if(err)
{
console.log("Error connecting to the database.");
throw err;
}
client.query("SELECT DISTINCT state FROM business ORDER BY state", function (err, result)
{
if(err)
{
console.log("Query resulted in an error.");
throw err;
}
console.log(result.rows[0]);
client.end(function (err)
{
if(err)
{
console.log("Error disconnecting from the databse.");
throw err;
}
});
});
});
Here is the pg-promise code that I tried:
var pgp = require('pg-promise');
var cn = {
host: 'localhost', // server name or IP address;
port: 5432,
database: 'Milestone1DB',
user: 'postgres',
password: 'thisissuchagoodpassword'
};
var db = pgp(cn); // database instance;
db.any("select distict state from business order by state;")
.then(data => {
console.log("DATA:", data);
})
.catch(error => {
console.log("ERROR:", error);
});
I must be missing something, but I don't know where to look. Thank you to anyone who can help me figure out what this error means.
Make sure you are not crossing a context boundary that is corrupting the net prototype chain and stripping away methods like Stream(). I ran into a similar unhandled Promise exception w Node 7.5 and pg-live-select. However it was intermittent because of the way the net reference was being passed around. I ended up using V8 inspector and putting a 'debugger' statement directly above line 13 in connection.js to catch the corruption.
node_modules/lib/connection.js:13
this.stream = config.stream || new net.Stream();
^
TypeError: net.Stream is not a constructor
at new Connection (node_modules/pg-live-select/node_modules/pg/lib/connection.js:13:34)
at new Client (node_modules/pg-live-select/node_modules/pg/lib/client.js:26:37)
at Object.create (node_modules/pg-live-select/node_modules/pg/lib/pool.js:27:24)
at Pool._createResource (node_modules/generic-pool/lib/generic-pool.js:325:17)
at Pool.dispense [as _dispense] (node_modules/generic-pool/lib/generic-pool.js:313:12)
at Pool.acquire (node_modules/generic-pool/lib/generic-pool.js:388:8)
at Pool.pool.connect (node_modules/pg-live-select/node_modules/pg/lib/pool.js:78:14)
at PG.connect (node_modules/pg-live-select/node_modules/pg/lib/index.js:49:8)
at LivePg._updateQuery (node_modules/pg-live-select/index.js:295:6)
at node_modules/pg-live-select/index.js:160:14
at Array.forEach (native)
at Timeout.performNextUpdate [as _onTimeout] (node_modules/pg-live-select/index.js:159:23)
at ontimeout (timers.js:365:14)
at tryOnTimeout (timers.js:237:5)
at Timer.listOnTimeout (timers.js:207:5)