Check Mongoose Connection Status
Jan 6, 2021
Mongoose connections have a readyState property that contains a number representing the current state of the connection, 0-4. These states are as follows:
- 0 = disconnected
- 1 = connected
- 2 = connecting
- 3 = disconnecting
- 4 = invalid credentials
These event names will emit when the state changes.
// Demonstrate the readyState and on event emitters
console.log(mongoose.connection.readyState); //logs 0
mongoose.connection.on('connecting', () => {
console.log('connecting')
console.log(mongoose.connection.readyState); //logs 2
});
mongoose.connection.on('connected', () => {
console.log('connected');
console.log(mongoose.connection.readyState); //logs 1
});
mongoose.connection.on('disconnecting', () => {
console.log('disconnecting');
console.log(mongoose.connection.readyState); // logs 3
});
mongoose.connection.on('disconnected', () => {
console.log('disconnected');
console.log(mongoose.connection.readyState); //logs 0
});
// Connect to a MongoDB server running on 'localhost:27017' and use the
// 'test' database.
await mongoose.connect('mongodb://localhost:27017/test', {
useNewUrlParser: true // Boilerplate for Mongoose 5.x
});
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