Loopback4 中包含记录的限制

如何解决Loopback4 中包含记录的限制

我想查询运动模型对象并包含相关对象（关系：athletExerciseLogsExercise）。但我只需要 1 个相关对象，这就是为什么我将“限制：1”添加到包含范围：

exerciseController.find({
    include: [{
        relation: "athletExerciseLogsExercise",scope: {
            where: {
                userId: id
            },order: ['date DESC'],limit: 1
        }
    },]
});

型号

export class Exercise extends Entity {
  ...
  @hasMany(() => AthletExerciseLog,{keyTo: 'exerciseId'})
  athletExerciseLogsExercise?: AthletExerciseLog[];
  ...
}

sql（来自调试）

SELECT
  "id","userid","exerciseid","date"
  ...
FROM
  "public"."athletexerciselog"
WHERE
  "userid" = '65b9b7110230'
  AND "exerciseid" IN (
    'd67503d511bb','46d156a58aee'
  )
ORDER BY  "date" DESC
LIMIT 1

问题：sql 结果只包含 1 个记录for one "exerciseid" = 'd67503d511bb'

问题：如何从“athletexerciselog”为每个“exerciseid”接收1条记录？

解决方法

我找到了以下解决方案，这可能是一个开销，但我找不到其他方法...

1 - 创建数据库视图：为每个 userid 和 exerciseid

仅选择 1（最后）条记录

CREATE VIEW "v_athletexerciselog" AS  
  SELECT q.*
  FROM athletexerciselog q
  WHERE (
        q.id IN ( 
          SELECT max(i.id) AS max
           FROM athletexerciselog i
          WHERE (i.event IS NULL)
          GROUP BY i.userid,i.exerciseid
        )
  )

2 - 创建一个新的 LB4 模型 和存储库 使用自定义表名（视图名）扩展原始模型

@model({
  settings: {
    postgresql: {schema: 'public',table: 'v_athletexerciselog'},// custom names
  },})
export class VAthletExerciseLog extends AthletExerciseLog {
  constructor(data?: Partial<VAthletExerciseLog>) {
    super(data);
  }
}

3 - 将练习模型和存储库中的相关模型名称更改为 VAthletExerciseLog（新）

export class Exercise extends Entity {
  ...
  @hasMany(() => VAthletExerciseLog,{keyTo: 'exerciseId'})
  athletExerciseLogsExercise?: VAthletExerciseLog[];
  ...
}

4 - 从查询中删除“订单”和“限制”：

exercise.find({
    include: [{
        relation: "athletExerciseLogsExercise",scope: {
            where: {
                userId: id
            },//order: ['date DESC'],//limit: 1
        }
    },]
});