用squeryl存储案例对象 [英] Storing case object with squeryl

问题描述

如何使用squeryl存储用户案例对象?我有一个Account对象，其权限字段为Permission(定义为密封特征)类型.我还从Permission扩展了2个案例对象(Administrator和NormalUser).如何使用Squeryl保留Account类.下面的示例代码:

How do I store user case objects with squeryl? I have an Account object with a permission field of type Permission (defined as a sealed trait). I also have 2 case objects (Administrator and NormalUser) extending from Permission. How can I persist the Account class using Squeryl. Example code below:

sealed trait Permission
case object Administrator extends Permission
case object NormalUser extends Permission

case class Account(
        id: Long, 
        email: String,
        permission: Permission
) extends KeyedEntity[Long]

推荐答案

请扩展我的评论，如果您使用自定义类型来检索权限类型，则该权限类型将作为整数持久化到数据库中(在下面的示例中为1)和0)，您可以覆盖unapply方法来查找case对象，并且模式匹配应该可以正常工作.我认为类似以下内容的方法应该起作用:

Expanding on my comment, if you use a custom type to retrieve the permission type, such that it persists to the database as an integer (in the example below 1 and 0), you can override the unapply method to lookup the case object and pattern matching should work fine. I imagine something like the following should work:

class Permission(identifier:Int) extends org.squeryl.customtypes.IntField(identifier) {
  self: CustomType[Int] =>

  private lazy val permissions = 
    List(Administrator, NormalUser).
      map(p => p.value -> p).
      toMap

  def unapply = permissions.get(value)
}

case object Administrator extends Permission(1)
case object NormalUser extends Permission(0)

然后，您应该能够使用您的实体定义将权限直接存储在代码中:

Then you should be able to store the permission directly in your code, using your entity definition:

case class Account(
        id: Long, 
        email: String,
        permission: Permission
) extends KeyedEntity[Long]

您可以直接将permission字段设置为Administrator或NormalUser，并且还应该能够像这样进行图案匹配:

you can set the permission field directly as Administrator or NormalUser and you should also be able to pattern match like:

account.permission match {
  case Administrator => ..
  case NormalUser => ..
}

这篇关于用squeryl存储案例对象的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！