TypeORM Querybuilder 获取嵌套的 INNER JOIN答案

【问题标题】：TypeORM Querybuilder get nested INNER JOINTypeORM Querybuilder 获取嵌套的 INNER JOIN
【发布时间】：2021-07-31 06:14:36
【问题描述】：

我有一个TripEntity，它在vehicle_id 列中引用了Vehicle。 VehicleEntity 本身在 vehicle_details_id 列中引用了 VehicleDetailsEntity。

旅行实体

id	vehicle_id
1	99

车辆实体

id	vehicle_details_id
99	100

VehicleDetailsEntity

id	registration_plate
100	DOGETOMOON

如何使用QueryBuilder 获取所有三个：TripEntity、VehicleEntity 和 VehicleDetails？

    const trip = await db
      .createQueryBuilder(TripEntity, "trip")
      .innerJoinAndSelect("trip.vehicle_id", "vehicle")
      /* This does not work...
      .innerJoinAndSelect("vehicle. vehicle_details_id", "details")
     */
      .where("trip.created_at >= :after",{ after })
      .getMany();

【问题讨论】：

标签： mysql node.js typeorm

【解决方案1】：

我认为明确定义连接条件可以解决问题。请检查以下查询 -

async findVehicleDetails(request): Promise<any>{
    return await getRepository(TripEntity).
    .createQueryBuilder("tripEntity")
    .innerJoinAndSelect("VehicleEntity","vehicleEntity","vehicleEntity.id = tripEntity.vehicle_id")
    .innerJoinAndSelect("VehicleDetailsEntity","vehicleDetailsEntity","vehicleDetailsEntity.id = vehicleEntity.vehicle_details_id")
    .where("tripEntity.created_at >= :after",{ after })
    .getMany()
}

【讨论】：

【解决方案2】：

如果你要加入多个实体，你可以试试innerJoinAndMapOne。

const trips = (await db
  .createQueryBuilder(TripEntity, "trip")
  .innerJoinAndMapOne(
    "trip.vehicle",
    VehicleEntity,
    "vehicle",
    "trip.vehicle_id = vehicle.id"
  )
  .innerJoinAndMapOne(
    "trip.vehicleDetails",
    VehicleDetailsEntity,
    "vehicle_details",
    "vehicle.vehicle_details_id = vehicle_details.id"
  )
  .where("trip.created_at >= :after", { after })
  .getMany()) as (TripEntity & {
    vehicle: VehicleEntity;
    vehicleDetails: VehicleDetailsEntity;
  })[];

【讨论】：