尝试获取2周前的所有记录 [英] Trying to get all records from 2 weeks ago

问题描述

我正在尝试从2周前创建的表中获取所有记录.

I'm trying to get all records from a table that were created 2 weeks ago.

我的方法如下:

 def getRecent(from: Instant): Future[Seq[User]] = {
    db.run(
      users.filter(f => f.status != 0 && f.createdAt > from ).sortBy(_.id.desc).result
    )
  }

我已经隐含了一个我认为可以使用的隐式功能，但我想它仅适用于读取行:

I have an implicit already that I thought would work but I guess it is only for reading rows:

class UsersTable(tag: Tag) extends Table[User](tag, "users") {

    implicit val dateColumnType = MappedColumnType.base[Instant, Timestamp](
      i => Timestamp.from(i),
      ts => {
        ts.toInstant

      }
    )

    def id = column[Int]("id", O.PrimaryKey)
    ....

错误是:

 value > is not a member of slick.lifted.Rep[java.time.Instant]

推荐答案

实际上，您已经快到了.它用于读取和写入.但事情是这样的:它必须在范围内(甚至用于过滤).

Actually you are nearly there. It is used for both read and writes. But here is the thing: it needs to be in scope (even for your filtering).

普通滑动解决方案

只需将您的转换放入这样的伴随对象中即可:

Just put your conversion into companion object like this:

object UserTable {
    implicit val dateColumnType = MappedColumnType.base[Instant, Timestamp](
      i => Timestamp.from(i),
      ts => {
        ts.toInstant

      }
    )
}

然后执行以下操作:

def getRecent(from: Instant): Future[Seq[User]] = {
    // I added this import here
    import UserTable.dateColumnType

    db.run(
      users.filter(f => f.status != 0 && f.createdAt > from ).sortBy(_.id.desc).result
    )
 }

Play-Slick解决方案

以上答案并不完全适合问题中未明确陈述的play-slick部分(尽管问题已标记为playframework).如果您使用的是play-slick，那么您的方法将是这样的:

Above answer doesn't really fit play-slick part which is not explicitly stated in the question (though question is tagged with playframework tag). If you are using play-slick than your approach would be something like this:

将您的对话放入trait(trait DbImplicits)，该对话需要与HasDatabaseConfigProvider混合在一起或扩展.

Put your conversation into trait (trait DbImplicits) that require to be mixed-in together with or extends HasDatabaseConfigProvider.

trait DbImplicits { self: HasDatabaseConfigProvider[JdbcProfile] =>
  import self.driver._

    implicit val dateColumnType = MappedColumnType.base[Instant, Timestamp](
        i => Timestamp.from(i),
        ts => {
           ts.toInstant
        }
    )
}

以后像这样使用它:

class MyClassUsingImplicits @Inject()(
    protected val dbConfigProvider: DatabaseConfigProvider
) extends HasDatabaseConfigProvider[JdbcProfile] 
  with DbImplicits {
  import driver._

  // your further code comes here
}

顺便说一句，我刚刚注意到此片段中的另一个错误:

BTW I just noticed another mistake in this fragment:

f.status != 0

您应该使用Slick运算符:

You should be using Slick operator:

f.status =!= 0

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