如何使用升降映射器访问链接表的字段

Question

从下面的 Lift-Web Mapper 模型中，如何访问 AssignmentformLink 下的字段？

object TForm extends TForm with LongKeyedMetaMapper[TForm]
class TForm extends LongKeyedMapper[TForm] with IdPK with ManyToMany {
  def getSingleton = TForm
  object label extends MappedString(this, 40)
  object pattern extends MappedString(this, 200)
  object assignments extends MappedManyToMany(
      AssignmentformLink, AssignmentformLink.assignment, AssignmentformLink.form, TForm)
}
object AssignmentformLink extends AssignmentformLink with LongKeyedMetaMapper[AssignmentformLink] {
  override def dbIndexes = Index(form, assignment) :: super.dbIndexes
}
class AssignmentformLink extends LongKeyedMapper[AssignmentformLink] with IdPK {
  def getSingleton = AssignmentformLink
  object form extends MappedLongForeignKey(this, TForm)
  object assignment extends MappedLongForeignKey(this, Assignment)
  object order extends MappedInt(this)
  object readonly extends MappedBoolean(this)
  object required extends MappedBoolean(this)
  object visible extends MappedBoolean(this)
}
object Assignment extends Assignment with LongKeyedMetaMapper[Assignment]
class Assignment extends LongKeyedMapper[Assignment] with IdPK with ManyToMany {
  def getSingleton = Assignment
  object id_parent extends MappedLong(this)
  object label extends MappedString(this, 40)
  object order extends MappedInt(this)
  object guard extends MappedString(this, 200)
  object forms extends MappedManyToMany(
      AssignmentformLink, AssignmentformLink.assignment, AssignmentformLink.form, TForm)
}

要获取 assign 及其链接的表单，请执行以下操作：

val assignments = Assignments.find(By(Assignment.id, 123))
assignments match {
  case Full(as) => {
    val forms = as.forms
.....

但是我不知道如何导航到AssignmentformLink下的order, readonly, required...字段。

我意识到我可以手动搜索链接，即。 AssignmentformLink.find(By(form...),By(assignment...))，但这会导致代码效率低下，并且确实错过了使用对象的意义。

我需要能够从表单导航到链接表的字段。

Answer 1

不知道这是否是正确的方法，但assignments.joins返回连接表记录的列表。