具有隐式 json 格式的 Scala activerecord

Question

我有一个 scala-activerecord:

case class Person(name: String) extends ActiveRecord with Timestamps
object Person extends ActiveRecordCompanion[Person]

一切正常。

突然想提供一个API并用实体的json表示回复，所以修改了代码：

case class Person(name: String) extends ActiveRecord with Timestamps
object Person extends ActiveRecordCompanion[Person] with DefaultJsonProtocol {
  implicit val jsonFormat = jsonFormat1(Request)
}

现在引发异常：

com.github.aselab.activerecord.SchemaSettingException: Cannot find table definition of class Person
  at com.github.aselab.activerecord.ActiveRecordException$.tableNotFound(ActiveRecordException.scala:48)
  at com.github.aselab.activerecord.Config$$anonfun$schema.apply(ActiveRecordConfig.scala:29)
  at com.github.aselab.activerecord.Config$$anonfun$schema.apply(ActiveRecordConfig.scala:29)
  at scala.collection.MapLike$class.getOrElse(MapLike.scala:128)
  at scala.collection.AbstractMap.getOrElse(Map.scala:59)
  at com.github.aselab.activerecord.Config$.schema(ActiveRecordConfig.scala:29)
  at com.github.aselab.activerecord.ActiveRecordBaseCompanion$class.schema(ActiveRecord.scala:116)
  at Person$.schema$lzycompute(Request.scala:12)
  at Person$.schema(Request.scala:12)
  at com.github.aselab.activerecord.ActiveRecordBaseCompanion$class.table(ActiveRecord.scala:123)
  at Person$.table$lzycompute(Request.scala:12)
  at Person$.table(Request.scala:12)
  at com.github.aselab.activerecord.ActiveRecordBaseCompanion$class.all(ActiveRecord.scala:133)
  at Person$.all(Request.scala:12)
  at com.github.aselab.activerecord.inner.CompanionIterable$class.companionToIterable(Implicits.scala:15)
  at Person$.companionToIterable(Request.scala:12)
  at Person$.<init>(Request.scala:13)
  at Person$.<clinit>(Request.scala)
  ... 34 more

编辑：我在 ActiveRecordConfig.scala:

中放置了两个断点

断点A在这里：

def schema(companion: ActiveRecordBaseCompanion[_, _]): ActiveRecordTables = {
  val clazz = companion.classInfo.clazz
  tables.getOrElse(clazz, throw ActiveRecordException.tableNotFound(clazz.toString))
}

此处为断点 B：

def registerSchema(s: ActiveRecordTables) = {
  conf = s.config
  s.all.foreach(t => _tables.update(t.posoMetaData.clasz, s))
}

使用第一个代码（没有 json 隐式）执行到达断点 B。

第二个代码（包括 json 隐式）执行首先到达断点 A，导致异常。

Answer 1

Json 支持 scala-activerecord 版本 0.3.1 中的工作，请参阅 wiki and this issue。至于现在，最新版本0.3.0你可以使用第一个代码和表单值反序列化：

case class Person(name: String) extends ActiveRecord with Timestamps
object Person extends ActiveRecordCompanion[Person]

在你的例子中喷雾控制器：

import spray.httpx.SprayJsonSupport._
import spray.json.DefaultJsonProtocol._

requestContext.complete(Person.find(id).toFormValues)

方法toFormValues会returnMap[String, String]，可以通过spray-json隐式转换为json.

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