我正在实施一个待办事项列表。一个用户可以有多个列表，一个列表可以有多个用户。我希望能够检索用户的所有列表，其中每个列表都包含共享它的用户列表（包括所有者）。未能成功实施此查询。
表定义：
case class DBList(id: Int, uuid: String, name: String)
class Lists(tag: Tag) extends Table[DBList](tag, "list") {
def id = column[Int]("id", O.PrimaryKey, O.AutoInc) // This is the primary key column
def uuid = column[String]("uuid")
def name = column[String]("name")
// Every table needs a * projection with the same type as the table's type parameter
def * = (id, uuid, name) <> (DBList.tupled, DBList.unapply)
}
val lists = TableQuery[Lists]
case class DBUser(id: Int, uuid: String, email: String, password: String, firstName: String, lastName: String)
// Shared user projection, this is the data of other users which a user who shared an item can see
case class DBSharedUser(id: Int, uuid: String, email: String, firstName: String, lastName: String, provider: String)
class Users(tag: Tag) extends Table[DBUser](tag, "user") {
def id = column[Int]("id", O.PrimaryKey, O.AutoInc) // This is the primary key column
def uuid = column[String]("uuid")
def email = column[String]("email")
def password = column[String]("password")
def firstName = column[String]("first_name")
def lastName = column[String]("last_name")
def * = (id, uuid, email, password, firstName, lastName) <> (DBUser.tupled, DBUser.unapply)
def sharedUser = (id, uuid, email, firstName, lastName) <> (DBSharedUser.tupled, DBSharedUser.unapply)
}
val users = TableQuery[Users]
// relation n:n user-list
case class DBListToUser(listUuid: String, userUuid: String)
class ListToUsers(tag: Tag) extends Table[DBListToUser](tag, "list_user") {
def listUuid = column[String]("list_uuid")
def userUuid = column[String]("user_uuid")
def * = (listUuid, userUuid) <> (DBListToUser.tupled, DBListToUser.unapply)
def pk = primaryKey("list_user_unique", (listUuid, userUuid))
}
val listToUsers = TableQuery[ListToUsers]
我创建了一个附加类来保存数据库列表对象+用户，我的目标是以某种方式将查询结果映射到此类的实例。
case class DBListWithSharedUsers(list: DBList, sharedUsers: Seq[DBSharedUser])
这是其中大部分的 SQL 查询，它首先获取用户的所有列表（内部查询），然后将列表与 list_user 与用户进行连接，以获取其余数据和每个列表的用户，然后它使用内部查询进行过滤。它不包含按部分分组
select * from list inner join list_user on list.uuid=list_user.list_uuid inner join user on user.uuid=list_user.user_uuid where list.uuid in (
select (list_uuid) from list_user where user_uuid=<myUserUuuid>
);
我测试了它并且它有效。我正在尝试在 Slick 中实现它，但出现编译器错误。我也不知道那部分的结构是否正确，但一直无法想出更好的结构。
def findLists(user: User) = {
val listsUsersJoin = listToUsers join lists join users on {
case ((listToUser, list), user) =>
listToUser.listUuid === list.uuid &&
listToUser.userUuid === user.uuid
}
// get all the lists for the user (corresponds to inner query in above SQL)
val queryToGetListsForUser = listToUsers.filter(_.userUuid===user.uuid)
// map to uuids
val queryToGetListsUuidsForUser: Query[Rep[String], String, Seq] = queryToGetListsForUser.map { ltu => ltu.listUuid }
// create query that mirrors SQL above (problems):
val queryToGetListsWithSharedUsers = (for {
listsUuids <- queryToGetListsUuidsForUser
((listToUsers, lists), users) <- listsUsersJoin
if lists.uuid.inSet(listsUuids) // error because inSet requires a traversable and passing a ListToUsers
} yield (lists))
// group - doesn't compile because above doesn't compile:
queryToGetListsWithSharedUsers.groupBy {case (list, user) =>
list.uuid
}
...
}
我怎样才能解决这个问题？
提前致谢
编辑：
我将这个紧急解决方案放在一起（至少它可以编译），我使用原始 SQL 执行查询，然后以编程方式进行分组，它看起来像这样：
case class ResultTmp(listId: Int, listUuid: String, listName: String, userId:Int, userUuid: String, userEmail: String, userFirstName: String, userLastName: String, provider: String)
implicit val getListResult = GetResult(r => ResultTmp(r.nextInt, r.nextString, r.nextString, r.nextInt, r.nextString, r.nextString, r.nextString, r.nextString, r.nextString))
val a = sql"""select (list.id, list.uuid, list.name, user.id, user.uuid, user.email, user.first_name, user.last_name, user.provider) from list inner join list_user on list.uuid=list_user.list_uuid inner join user on user.uuid=list_user.user_uuid where list.uuid in (
select (list_uuid) from list_user where user_uuid=${user.uuid}
);""".as[ResultTmp]
val result: Future[Vector[ResultTmp]] = db.run(a)
val res: Future[Seq[DBListWithSharedUsers]] = result.map {resultsTmp =>
val myMap: Map[String, Vector[ResultTmp]] = resultsTmp.groupBy { resultTmp => resultTmp.listUuid }
val r: Iterable[DBListWithSharedUsers] = myMap.map {case (listUuid, resultsTmp) =>
val first = resultsTmp(0)
val list = DBList(first.listId, listUuid, first.listName)
val users: Seq[DBSharedUser] = resultsTmp.map { resultTmp =>
DBSharedUser(resultTmp.userId, resultTmp.userUuid, resultTmp.userEmail, resultTmp.userFirstName, resultTmp.userLastName, resultTmp.provider)
}
DBListWithSharedUsers(list, users)
}
r.toSeq
}
但这太可怕了，我怎样才能让它正常工作？
编辑2：
我正在尝试单子连接，但也被困在这里。例如，这样的事情会得到给定用户的所有列表：
val listsUsersJoin = for {
list <- lists
listToUser <- listToUsers
user_ <- users if user_.uuid === user.uuid
} yield (list.uuid, list.name, user.uuid, user.firstName ...)
但这还不够，因为我还需要获取这些列表的所有用户，所以我需要 2 个查询。所以我需要首先获取用户的列表，然后找到这些列表的所有用户，例如：
val queryToGetListsForUser = listToUsers.filter(_.userUuid===user.uuid)
val listsUsersJoin = for {
list <- lists
listToUser <- listToUsers
user_ <- users /* if list.uuid is in queryToGetListsForUser result */
} yield (list.uuid, list.name, user.uuid, user.firstName ... )
但我不知道如何将其传递给联接。我什至不确定 groupBy 是否正确，至少在数据库级别是正确的，到目前为止，我看到这仅用于将结果聚合为单个值，例如 count 或 avg。我需要它们在一个集合中。
编辑3：
我还不知道这是否正确，但一元连接可能是解决方案的途径。这编译：
val listsUsersJoin = for {
listToUser <- listToUsers if listToUser.userUuid === user.uuid // get the lists for the user
list <- lists if list.uuid === listToUser.listUuid // join with list
listToUser2 <- listToUsers if list.uuid === listToUser.listUuid // get all the users for the lists
user_ <- users if user_.uuid === listToUser2.userUuid // join with user
} yield (list.uuid, list.name, user.uuid, user.email, user.firstName, user.lastName)