Connection manager

The connections manager class is responsible for managing one or more database connection instances. You can access the manager from the Database module.

import Database from '@ioc:Adonis/Lucid/Database'

const manager = Database.manager

Methods/properties

Following is the list of methods/properties available on the connection manager class. Usually, you don't have to interact with the manager directly, as the following methods are invoked internally.

add

Register a new connection to the manager by providing the connection name and it's configuration. The database module automatically registers all the connections defined inside the config/database.ts file.

const name = 'pg'

const config = {
  client: 'pg',
  connection: {
    // ...
  },
  healthCheck: true
}

Database.manager.add(name, config)

connect

The connect method instantiates a pre-registered connection by its name. Under the hood, it calls the connect method on the Connection class .

Calling this method multiple times results is a no-op.

Database.manager.connect('pg')

get

Returns the connection node for a pre-registered connection by its name.

const {
  name,
  state,
  connection,
  config
} = Database.manager.get('pg')

Following is the list of available properties.

name

The name of the connection, as defined at the time of adding it.

config

Reference to the registered config

connection

Reference to the underlying connection class instance.

state

The current state of the connection.

• registered: The connection has been registered using the add method.
• open: The connection is open to accept new requests.
• closing: In the process of closing the connection. No new queries can be created or executed from this connection anymore.
• closed: The connection has been closed and cannot accept any more request. You must call the connect method again.
• migrating: The connection config has been patched and it is migrating to create a new connection instance with the new config.

has

Returns a boolean telling if the connection has been registered with the manager or not.

if (!Database.manager.has('pg')) {
  Database.manager.add('pg', {})
}

isConnected

Find if a connection is in open state or not.

if (!Database.manager.isConnected('pg')) {
  Database.manager.connect('pg')
}

patch

The patch method allows you to update the config for a given connection without closing the existing connection or aborting the ongoing queries.

After the connection has been patched, all new queries will use the newer config.

The patch method is really helpful when you have a multi-tenant app and you want to register connections on the fly for the tenants.

Database.manager.patch('pg', {
  client: 'pg',
  connection: {},
})

// Uses new config
Database.manager.connect('pg')

close

Close a given connection. The connection manager will still keep the connection node until you release the connection explicitly by passing the second argument.

// Close
await Database.manager.close('pg')
Database.manager.has('pg') // true

// Close + Release
await Database.manager.close('pg', true)
Database.manager.has('pg') // false

closeAll

Close all registered connections. A boolean parameter can be passed to also release the connection.

await Database.manager.closeAll()
await Database.manager.closeAll(true)

release

Release a connection from the managed list of connections. The connection will be closed automatically (if not already closed).

await Database.manager.release(true)

report

Returns the health check report for all the registered connections.

const report = await Database.manager.report()

console.log(report.name)
console.log(report.health.healthy)

Events

Following is the list of events emitted by the connection manager class.

db:connection:connect

Emitted when the connect method is called

Database.manager.on('db:connection:connect', (connection) => {
  console.log(self === connection) // true
})

db:connection:error

Emitted when the unable to establish the connection

Database.manager.on('db:connection:error', (error, connection) => {
  console.log(connection)
})

db:connection:disconnect

Emitted when the connection and Knex instance(s) have been destroyed.

Database.manager.on('db:connection:disconnect', (connection) => {
  console.log(connection)
})

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