如何在 Anorm 和 Play Framework 中使用可空列？

发布于 2024-11-29 10:23:15 字数 663 浏览 5 评论 0原文

我有一个案例类 MyRecord，我想将其用于结果集中的每一行：

case class MyRecord(id: Int, remindeMe: Option[org.joda.time.DateTime])

How do I SELECT all rows in a table and return a List of MyRecord using Scala and Anorm with Play Framework?

我尝试过：

def getRecords() : List[MyRecord] = {
      val records = SQL("SELECT id, data FROM mytable")().collect {
          case Row(id: Int, Some(data: Long)) => 
                      MyRecord(id, new org.joda.time.DateTime(data))
     }
}

如果列data为空，我想要None，否则我想要Some(data)作为案例类中的remindMe。是的，上面的Scala代码是非常错误的，但我不明白如何解决这个问题。

原文

I have a case class MyRecord that I want to use for every row in a resultset:

case class MyRecord(id: Int, remindeMe: Option[org.joda.time.DateTime])

How do I SELECT all rows in a table and return a List of MyRecord using Scala and Anorm with Play Framework?

I have tried with:

def getRecords() : List[MyRecord] = {
      val records = SQL("SELECT id, data FROM mytable")().collect {
          case Row(id: Int, Some(data: Long)) => 
                      MyRecord(id, new org.joda.time.DateTime(data))
     }
}

If the column data is null I want None otherwise I want Some(data) as remindMe in the case class. Yes, the above Scala code is very wrong, but I don't understand how to solve this.

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皓月长歌 2024-12-06 10:23:15

这应该可以工作，因为您已经定义了选项：

def getRecords() : List[MyRecord] = {
      SQL("SELECT id, data FROM mytable")().collect {
          case Row(id: Int, Some(data: Long)) => 
                  MyRecord(id, Some(new org.joda.time.DateTime(data)))
          case Row(id: Int, None) => 
                  MyRecord(id, None)

     }
}

您粘贴的情况将忽略所有 None 结果，因为它们与 Some(data) 不匹配

编辑：在末尾添加“toList”可以解决它，正如@kassens所说。我在 Play 1.2.2-Scala 0.91 环境中测试了它。有办法给他积分吗？ :)

This should work as you have already defined the Option:

def getRecords() : List[MyRecord] = {
      SQL("SELECT id, data FROM mytable")().collect {
          case Row(id: Int, Some(data: Long)) => 
                  MyRecord(id, Some(new org.joda.time.DateTime(data)))
          case Row(id: Int, None) => 
                  MyRecord(id, None)

     }
}

The case that you paste would ignore all the None results as they would not match Some(data)

EDIT: adding the "toList" at the end solves it, as @kassens said. I tested it in a Play 1.2.2-Scala 0.91 env. There's a way to give the points to him? :)

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