im using mongoclient and im sure that I have connection to the database
const client = new MongoClient(uri);
const datatbaseslist = client.db().admin().listDatabases();
datatbaseslist.databases.forEach(db => {
console.log($db.name)
});
I saw that code in a video of the mongodb and its not working.
thanks
I have tried looking for other versions to that line
const datatbaseslist = client.db().admin().listDatabases();
datatbaseslist.databases.forEach(db => {
console.log($db.name)
});
because im pretty sure that the problem is there.
I think your question title is saying one thing (collections) and your code is confusing this any another (databases).
A mongodb server can have multiple databases.
A database can have multiple collections.
You connect to the server using a client.
Normally if you want to know about the databases, you would use admin(). Or to connect to a specific database (although you can connect via URI), the you use db(dbName) from the client.
Once you have a db object, you can get the collections from there.
The below code shows you how to get both databases and collections.
const { MongoClient } = require('mongodb')
async function main () {
// Set config
const uri = 'mongodb://localhost:27017'
const client = new MongoClient(uri)
try {
// Connect to the MongoDB cluster
await client.connect()
// Get databases
const databasesList = await client.db().admin().listDatabases()
for (const dbName of databasesList.databases.map(db => db.name)) {
console.log('DB: ', dbName)
// Get collections for each database
const collections = await client.db(dbName).listCollections().toArray()
console.log('Collections:', collections.map(col => col.name).join(', '))
console.log('---------------------------------------------')
}
} catch (e) {
// Handle any erros
console.error(e)
} finally {
// Always close the connection to the database when finished
await client.close()
}
}
main().catch(console.error)
I am using mongodb on typescript and my problem is that the connections don't close after querying.
I had the following approach in doing it:
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!;
}
and I use it in my nodejs server by doing:
const { db } = await connectToDatabase(config.URI, DB_NAME);
const result = await db.collection(COLLECTION_NAME).aggregate([MyPipelines])
I have the database on Atlas and if I go to the dashboard I see a lot of connections not closed, and when it reaches 500 then the server need to be stopped because it goes in timeout and closes it. They send me one email saying "You're nearing the maximum connections treshold"
In fact now I have all these connections active.
And on console I get these errors:
What do you think I did wrong? Is there a better way to handle mongoDB connection with typescript?
You should close all connections when your app closes completely.
process.on('SIGINT', async () => {
await cachedConnection.db.close();
process.exit(0);
});
Please I am using the MongoDB database for my next application that is my final project for me Bootcamp and there is this error that has prevented me from making queries to my database as I always get the mongoclient not connected error.
I am using mongoose and this error started after I upgraded to the latest mui(material UI) because that is what I am using for this application. I have been trying since yesterday to fix this error as I thought it is something I could handle but till this moment it persist. It has been going from this mongoose MongoNotConnectedError: MongoClient must be connected to perform this operation and this one MongoExpiredSessionError: Cannot use a session that has ended` and it happens on every button that clicks that makes a request to the database.
Below is the code I am using to connect to MongoDB with mongoose:
import mongoose from 'mongoose';
const connection = {};
async function connect() {
if (connection.isConnected) {
console.log('already connected');
return;
}
if (mongoose.connections.length > 0) {
connection.isConnected = mongoose.connections[0].readyState;
if (connection.isConnected === 1) {
console.log('use previous connection');
return;
}
await mongoose.disconnect();
}
const db = await mongoose.connect(process.env.MONGODB_URI, {
useNewUrlParser: true,
useUnifiedTopology: true,
});
console.log('new connection');
connection.isConnected = db.connections[0].readyState;
}
async function disconnect() {
if (connection.isConnected) {
if (process.env.NODE_ENV === 'production') {
await mongoose.disconnect();
connection.isConnected = false;
} else {
console.log('not disconnect');
}
}
}
function convertDocToObj(doc) {
doc._id = doc._id.toString();
doc.createdAt = doc.createdAt.toString();
doc.updatedAt = doc.updatedAt.toString();
return doc;
}
const db = { connect, disconnect, convertDocToObj };
export default db;
I will really appreciate it so much if anybody can help me out with this problem, please. I don't know what is causing it or where it is coming from as I have tried to as much as i can to all to no0 avail
Thanks
I see that you are using the mongo URL as an environment variable with MONGODB_URI.
Do you have the dotenv module installed? Did you require('dotenv').config() in your applications? is the `.env file in the root directory of your project?
If so, if you are using MongoDB Atlas, make sure the URL in your .env file is the correct one. When you generate the connection string from MongoDB Atlas it gives a default DB in the URL string named myFirstDatabase or something like that. Change it to the DB you want to connect to.
Hi is there a way to switch database with mongoose?
I thought I could do it like that:
mongoose.disconnect();
mongoose.connect('localhost',db);
but it does not work I receive this error:
Error: Trying to open unclosed connection.
I do not know if it is because is asynchronous
As already stated you could do it using useDb function :
Example code :
async function myDbConnection() {
const url = 'mongodb+srv://username:password#cluster0-pauvx.mongodb.net/test?retryWrites=true&w=majority';
try {
await mongoose.connect(url, { useNewUrlParser: true });
console.log('Connected Successfully')
// Here from above url you've already got connected to test DB,
So let's make a switch as needed.
mongoose.connection.useDb('myDB'); // Switching happens here..
/**
* Do some DB transaction with mongoose models as by now models has already been registered to created DB connection
*/
} catch (error) {
console.log('Error connecting to DB ::', error);
}
}
Or if you wanted to create a complete new connection then you've to try mongoose.createConnection(). Just for reference in case of mongoDB driver you would use ::
mongodb.MongoClient.connect(mongourl, function(err, primaryDB) {
// open another database over the same connection
const secondaryDB = primaryDB.db(SECONDARY_DATABASE_NAME);
// now you can use both `database` and `database2`
...
});
Ref : mongoose multiple different connections, mongoose useDb(), mongoDB driver switch connections
It is asynchronous. If you pass a callback function to disconnect and try to connect to the next database in that callback, it will work.
Ex.
var mongoose = require('mongoose')
mongoose.connect('mongodb://localhost/test1', function() {
console.log('Connected to test 1')
mongoose.disconnect(connectToTest2)
})
function connectToTest2() {
mongoose.connect('mongodb://localhost/test2', function() {
console.log('Connected to test 2')
process.exit()
})
}
The top-voted answer had thrown me in a loop for a few hours. To help the OP and others who may have the same issue, here's my take on the solution:
Suppose you have two databases with the same schema and you want to switch between them on the fly. Let's call them DB1 and DB2. Here's how you can go about doing that:
(async () => {
const connection = await mongoose.createConnection(url, options);
const getModel = (database) => {
const dbConnection = connection.useDb(database);
return dbConnection.model('Model', modelSchema);
};
const Db1Model = getModel('DB1');
const Db2Model = getModel('DB2');
})();
Tested on Node.js v12 and Mongoose v5.
One way you can achieve this is by appending the database name with the database URL. For eg: if you are working with localhost
mongoose.connect('mongodb://localhost:portNumber/xyz_db');
When you connect like this, all your models will be saved in the xyz_db under your model as a collection.
You should use the useDb function like so:
mongoose.connect(process.env.MONGO_URI, {
useNewUrlParser: true,
useUnifiedTopology: true
});
mongoose.connection.useDb('Users'); # Change the string to the name of the database you want to use
I'm preparing a database creation script in Node.js and Mongoose.
How can I check if the database already exists, and if so, drop (delete) it using Mongoose?
I could not find a way to drop it with Mongoose.
There is no method for dropping a collection from mongoose, the best you can do is remove the content of one :
Model.remove({}, function(err) {
console.log('collection removed')
});
But there is a way to access the mongodb native javascript driver, which can be used for this
mongoose.connection.collections['collectionName'].drop( function(err) {
console.log('collection dropped');
});
Warning
Make a backup before trying this in case anything goes wrong!
Mongoose will create a database if one does not already exist on connection, so once you make the connection, you can just query it to see if there is anything in it.
You can drop any database you are connected to:
var mongoose = require('mongoose');
/* Connect to the DB */
mongoose.connect('mongodb://localhost/mydatabase',function(){
/* Drop the DB */
mongoose.connection.db.dropDatabase();
});
If you modify #hellslam's solution like this then it will work
I use this technique to drop the Database after my integration tests
//CoffeeScript
mongoose = require "mongoose"
conn = mongoose.connect("mongodb://localhost/mydb")
conn.connection.db.dropDatabase()
//JavaScript
var conn, mongoose;
mongoose = require("mongoose");
conn = mongoose.connect("mongodb://localhost/mydb");
conn.connection.db.dropDatabase();
HTH at least it did for me, so I decided to share =)
Tried #hellslam's and #silverfighter's answers. I found a race condition holding my tests back. In my case I'm running mocha tests and in the before function of the test I want to erase the entire DB. Here's what works for me.
var con = mongoose.connect('mongodb://localhost/mydatabase');
mongoose.connection.on('open', function(){
con.connection.db.dropDatabase(function(err, result){
done();
});
});
You can read more https://github.com/Automattic/mongoose/issues/1469
An updated answer, for 4.6.0+, if you have a preference for promises (see docs):
mongoose.connect('mongodb://localhost/mydb', { useMongoClient: true })
.then((connection) => {
connection.db.dropDatabase();
// alternatively:
// mongoose.connection.db.dropDatabase();
});
I tested this code in my own code, using mongoose 4.13.6. Also, note the use of the useMongoClient option (see docs). Docs indicate:
Mongoose's default connection logic is deprecated as of 4.11.0. Please opt in to the new connection logic using the useMongoClient option, but make sure you test your connections first if you're upgrading an existing codebase!
The difficulty I've had with the other solutions is they rely on restarting your application if you want to get the indexes working again.
For my needs (i.e. being able to run a unit test the nukes all collections, then recreates them along with their indexes), I ended up implementing this solution:
This relies on the underscore.js and async.js libraries to assemble the indexes in parellel, it could be unwound if you're against that library but I leave that as an exerciser for the developer.
mongoose.connection.db.executeDbCommand( {dropDatabase:1}, function(err, result) {
var mongoPath = mongoose.connections[0].host + ':' + mongoose.connections[0].port + '/' + mongoose.connections[0].name
//Kill the current connection, then re-establish it
mongoose.connection.close()
mongoose.connect('mongodb://' + mongoPath, function(err){
var asyncFunctions = []
//Loop through all the known schemas, and execute an ensureIndex to make sure we're clean
_.each(mongoose.connections[0].base.modelSchemas, function(schema, key) {
asyncFunctions.push(function(cb){
mongoose.model(key, schema).ensureIndexes(function(){
return cb()
})
})
})
async.parallel(asyncFunctions, function(err) {
console.log('Done dumping all collections and recreating indexes')
})
})
})
This works for me as of Mongoose v4.7.0:
mongoose.connection.dropDatabase();
2020 update
make a new file call it drop.js i.e
and put inside
require('dotenv').config()
const url = process.env.ATLAS_URI;
mongoose.connect(url, {
useNewUrlParser: true,
useCreateIndex: true,
useUnifiedTopology: true,
useFindAndModify: false
});
const connection = mongoose.connection;
connection.once('open', () => {
console.log("MongoDB database connection established successfully");
})
mongoose.connection.dropDatabase().then(
async() => {
try {
mongoose.connection.close()
}
catch (err) {
console.log(err)
}
}
);
in your package.json
in your package.json
"scripts": {
"drop": "node models/drop.js",
}
run it on ur console and
To empty a particular collection in a database:
model.remove(function(err, p){
if(err){
throw err;
} else{
console.log('No Of Documents deleted:' + p);
}
});
Note:
Choose a model referring to particular schema(schema of collection
you wish to delete).
This operation will not delete collection name
from database.
This deletes all the documents in a collection.
The best way to drop your database in Mongoose depends on which version of Mongoose you are using. If you are using a version of Mongoose that 4.6.4 or newer, then this method added in that release is likely going to work fine for you:
mongoose.connection.dropDatabase();
In older releases this method did not exist. Instead, you were to use a direct MongoDB call:
mongoose.connection.db.dropDatabase();
However, if this was run just after the database connection was created, it could possibly fail silently. This is related to the connection actually be asynchronous and not being set up yet when the command happens. This is not normally a problem for other Mongoose calls like .find(), which queue until the connection is open and then run.
If you look at the source code for the dropDatabase() shortcut that was added, you can see it was designed to solve this exact problem. It checks to see if the connection is open and ready. If so, it fires the command immediately. If not, it registers the command to run when the database connection has opened.
Some of the suggestions above recommend always putting your dropDatabase command in the open handler. But that only works in the case when the connection is not open yet.
Connection.prototype.dropDatabase = function(callback) {
var Promise = PromiseProvider.get();
var _this = this;
var promise = new Promise.ES6(function(resolve, reject) {
if (_this.readyState !== STATES.connected) {
_this.on('open', function() {
_this.db.dropDatabase(function(error) {
if (error) {
reject(error);
} else {
resolve();
}
});
});
} else {
_this.db.dropDatabase(function(error) {
if (error) {
reject(error);
} else {
resolve();
}
});
}
});
if (callback) {
promise.then(function() { callback(); }, callback);
}
return promise;
};
Here's a simple version of the above logic that can be used with earlier Mongoose versions:
// This shim is backported from Mongoose 4.6.4 to reliably drop a database
// http://stackoverflow.com/a/42860208/254318
// The first arg should be "mongoose.connection"
function dropDatabase (connection, callback) {
// readyState 1 === 'connected'
if (connection.readyState !== 1) {
connection.on('open', function() {
connection.db.dropDatabase(callback);
});
} else {
connection.db.dropDatabase(callback);
}
}
Mongoose 4.6.0+:
mongoose.connect('mongodb://localhost/mydb')
mongoose.connection.once('connected', () => {
mongoose.connection.db.dropDatabase();
});
Passing a callback to connect won't work anymore:
TypeError: Cannot read property 'commandsTakeWriteConcern' of null
beforeEach((done) => {
mongoose.connection.dropCollection('products',(error ,result) => {
if (error) {
console.log('Products Collection is not dropped')
} else {
console.log(result)
}
done()
})
})
To drop all documents in a collection:
await mongoose.connection.db.dropDatabase();
This answer is based off the mongoose index.d.ts file:
dropDatabase(): Promise<any>;
mongoose.connect(`mongodb://localhost/${dbname}`, {
useNewUrlParser: true,
useCreateIndex: true,
useFindAndModify: true,
useUnifiedTopology: true
})
.then((connection) => {
mongoose.connection.db.dropDatabase();
});
To delete a complete database, just pass the name...
This one is working perfectly fine on version 4.4
Since the remove method is depreciated in the mongoose library we can use the deleteMany function with no parameters passed.
Model.deleteMany();
This will delete all content of this particular Model and your collection will be empty.
For dropping all documents in a collection:
myMongooseModel.collection.drop();
as seen in the tests