`@dandi-contrib/data-pg` wraps the [node-postgres](https://node-postgres.com/) client in implementations of `@dandi/data`'s interfaces.
npm install @dandi-contrib/data-pg@dandi-contrib/data-pg wraps the node-postgres
client in implementations of @dandi/data's interfaces.
See @dandi/data for basic usage and configuration.
In addition to setting up the connection and authentication data
described in @dandi/data, include PgDbModule
in your DandiApplication providers:
``typescript
import { DandiApplication } from '@dandi/core'
import { PgDbModule } from '@dandi-contrib/data-pg'
const myApp = new DandiApplication({
providers: [
...
// database
PgDbModule,
...
],
})
`
Include a Provider for PgDbModelBuilderOptions
in your providers:
`typescript
import { DandiApplication } from '@dandi/core'
import { PgDbModelBuilderOptions, PgDbModule } from '@dandi-contrib/data-pg'
import { ModelBuilderOptions } from '@dandi/model-builder'
import { camel } from 'change-case'
const myApp = new DandiApplication({
providers: [
...
ModelBuilderOptions.provider(PgDbModelBuilderOptions, {
keyTransform: camel, // translates snake_case table column names to camelCase
}),
...
],
})
`
Expansion for Nested Models@dandi/data-pg's DbQueryable implementation allows you to map columns from SELECT statements for models that nest
other models. To enable this feature, you must construct your query in a specific manner:
- Add aliases to the table identifier that match the name of the property
- Include only the aliases of the tables you wish to include in the SELECT statement.
For example, given a model structure like so:
`typescript
class CarModel {
@Property(Uuid)
public carId: Uuid
@Property(String)
public name: string
}
class DriverModel {
@Property(Uuid)
public driverId: Uuid
@Property(String)
public name: string
}
class DriverAssignmentModel {
@Property(DriverModel)
public driver: DriverModel
@Property(CarModel)
public car: CarModel
}
`
The query might look like:
`sql`
SELECT
driver,
car
FROM driver_assignments a
JOIN drivers driver ON a.driver_id = driver.driver_id
JOIN cars car ON a.car_id = car.car_id
Calling dbClient.queryModel(DriverAssignmentModel, query) with the above query would result in the following expansion:
`sql`
SELECT
driver.driver_id as "driver.driver_id",
driver.name as "driver.name",
car.car_id as "car.car_id",
car.name as "car.name"
FROM driver_assignments a
JOIN drivers driver ON a.driver_id = driver.driver_id
JOIN cars car ON a.car_id = car.car_id
The dot notation in the above expanded query, combined with a camelCase key transform (as shown above) will allow the
ModelBuilder` instance to correctly map the properties into their respective models.