Multiple database connections on Yii3

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1

Hi everyone,

I’m currently working with Yii3 and I’m trying to understand the best way to handle multiple database connections.

In Yii2 this was quite straightforward and well-documented, but in Yii3 I’m honestly struggling to find a clear and practical approach. The documentation and examples I’ve found so far are a bit confusing, and I’m not sure what the recommended pattern is.

My use case is simple: I need to work with more than one database connection within the same application (e.g., different tenants or separate data sources).

So my questions are:

  • Is there an official or recommended way to configure and manage multiple DB connections in Yii3?
  • Are there any examples or best practices available?
  • How should this be integrated with repositories / Active Record (if applicable)?

Any guidance, examples, or pointers to documentation would be greatly appreciated.

Thanks in advance!

2

You can use class aliases.

3

Hi, thanks for your reply. I actually found the answer later in the DB documentation — my bad.

Now I was wondering how Active Record management with multiple DbConnection is supposed to work in Yii3. Coming from Yii2, each Active Record had its own connection defined, while here it seems a bit more complex. From what I understand, Yii3 relies on a ConnectionProvider (or DI), but then you need to instantiate Active Records through a factory, and you also lose access to their static methods — meaning, for example, you can’t directly use methods provided by RepositoryTrait.

One idea I had was to switch the connection in the provider right before using each Active Record. However, I’m not sure if that’s safe — especially if different Active Records are used sequentially, or if an instance created with a previous connection is reused after the provider has changed. That could potentially lead to inconsistent behavior.

I suspect I might still be reasoning with a Yii2 mindset. Would the correct approach be to rely on repositories that inject the proper connection into the Active Record?

Apologies if this is a naive question — I’ve only recently started exploring Yii3. Thanks in advance to anyone who can clarify this!

4

In my opinion, Active Record is not the most appropriate way to handle multiple database connections since it requires a ConnectionInterface to be injected into each model.
You may wish to consider alternative methods, such as Yii DB or Doctrine ORM.

5

Hi,

I did some reverse engineering and found out that ConnectionProvider actually accepts an array of connections. So it’s possible to configure multiple connections directly in the bootstrap definition, for example:

/**
 * @psalm-var list<callable(ContainerInterface): void>
 */
return [
    static function (ContainerInterface $container): void {
        ConnectionProvider::set($container->get(ConnectionInterface::class)); // default connection
        ConnectionProvider::set($container->get(ConnectionB::class), 'connectionB'); // other connection
    }
];

With this approach, you can override the db() method in your class that extends ActiveRecord and return the desired connection:

class Users extends ActiveRecord
{
    use MagicPropertiesTrait;
    use RepositoryTrait;

    public function db(): ConnectionInterface
    {
        return ConnectionProvider::get('connectionB');
    }

    public function tableName(): string
    {
        return 'users';
    }
}

This way, you can still use static methods like ::query() or those provided by RepositoryTrait. Internally, when static methods are called, they just instantiate an ActiveQuery passing the calling model class (e.g. Users::class). Then it simply creates an instance and calls the db() method to resolve the connection.