Multi-database/Multi-datasource

Vona ORM supports Multi-database/Multi-datasource, with the following features:

1. Multi-database
   • For example: PostgreSQL/MySQL
   • Support for new database dialects is continuously being added
2. Multi-datasource
3. Cross-datasource relation queries

The following example uses the User/Order model to query a user's order list to demonstrate how to use Multi-database/Multi-datasource

Preparing Models

First prepare two Models: User/Order

1. Model Order

@Model({
  entity: EntityOrder,
})
class ModelOrder{}

2. Model User

@Model({
  entity: EntityUser,
  relations: {
    orders: $relation.hasMany(() => ModelOrder, 'userId'),
  },
})
class ModelUser {}

Query data

Then query the user's order list

class ServiceOrder {
  async selectUserOrders() {
    const userId = 1;
    const userAndOrders = await this.scope.model.user.get(
      {
        id: userId,
      },
      {
        include: {
          orders: true,
        },
      },
    );
  }
}

So far, system default datasource has been used to query the user information of userId=1 and the order list of this user

Create Datasources

Next, create two datasources: user-pg and order-mysql

1. Add datasource type definition

• In VSCode, create a type file in the module through the context menu Vona Init/Types

• Then add the type definition in the type file

{module path}/src/types/index.ts

declare module 'vona-module-a-orm' {
  export interface IDatabaseClientRecord {
    'user-pg': never;
    'order-mysql': never;
  }
}

2. Datasources configuration

src/backend/config/config/config.ts

// database
config.database = {
  clients: {
    'user-pg': {
      client: 'pg',
      connection: {
        host: '127.0.0.1',
        port: 5432,
        user: 'postgres',
        password: '',
        database: 'user-xxx',
      },
    },
    'order-mysql': {
      client: 'mysql2',
      connection: {
        host: '127.0.0.1',
        port: 3306,
        user: 'root',
        password: '',
        database: 'order-xxx',
      },
    },
  },
};

Using Datasources: Dynamic Way

You can use datasources dynamically in your code:

class ServiceOrder {
  async selectUserOrders() {
    const userId = 1;
+   const modelUser = this.scope.model.user.newInstance('user-pg');
    const userAndOrders = await modelUser.get(
      {
        id: userId,
      },
      {
        include: {
          orders: true,
        },
      },
    );
  }
}

• newInstance: Passes the datasource to use and returns a new model instance

So far, we've used the user-pg datasource to query user information and the system default datasource to query order list

Using Datasources: Relation dynamic options

The datasource can be specified dynamically in the relation options:

class ServiceOrder {
  async selectUserOrders() {
    const userId = 1;
    const modelUser = this.scope.model.user.newInstance('user-pg');
    const userAndOrders = await modelUser.get(
      {
        id: userId,
      },
      {
        include: {
          orders: {
+           meta: {
+             client: 'order-mysql',
+           },
          },
        },
      },
    );
  }
}

• meta.client: specifies the datasource to be used by relation orders

So far, we use the datasource user-pg to query user information and the datasource order-mysql to query order list

Using Datasources: Model options

You can also configure the datasource directly in the Model options to simplify the query code

1. Model Order

@Model({
  entity: EntityOrder,
+ client: 'order-mysql',
})
class ModelOrder{}

2. Model User

@Model({
  entity: EntityUser,
+ client: 'user-pg',
  relations: {
    orders: $relation.hasMany(() => ModelOrder, 'userId'),
  },
})
class ModelUser {}

3. Query data

Now, you can query the user's order list in the usual way

class ServiceOrder {
  async selectUserOrders() {
    const userId = 1;
    const userAndOrders = await this.scope.model.user.get(
      {
        id: userId,
      },
      {
        include: {
          orders: true,
        },
      },
    );
  }
}

Using Datasources: App Config

You can also configure Model options in App Config:

src/backend/config/config/config.ts

// onions
config.onions = {
  model: {
    'test-vona:user': {
      client: 'user-pg',
    },
    'test-vona:order': {
      client: 'order-mysql',
    },
  },
};

Therefore, you can also use the usual way to query the user's order list

Using Datasources: Relation static options

Static options can also be specified when defining a Relation:

@Model({
  entity: EntityUser,
  client: 'user-pg',
  relations: {
    orders: $relation.hasMany(() => ModelOrder, 'userId', {
+     meta: {
+       client: 'order-mysql',
+     },
    }),
  },
})
class ModelUser {}

Similarly, you can also use the usual way to query the user's order list