Play + Anorm + Postgres-将json值加载到case类中 [英] Play + Anorm + Postgres - load json value into a case class
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问题描述
我正在使用anorm来查询元素并将其保存到我的postgres数据库中. 我有一个json列,我想将其作为自己的类阅读.
I am using anorm to query and save elements into my postgres database. I have a json column which I want to read as class of my own.
例如,如果我有以下课程
So for example if I have the following class
case class Table(id: Long, name:String, myJsonColumn:Option[MyClass])
case class MyClass(site: Option[String], user:Option[String])
我正在尝试编写以下更新:
I am trying to write the following update:
DB.withConnection { implicit conn =>
val updated = SQL(
"""UPDATE employee
|SET name = {name}, my_json_column = {myClass}
|WHERE id = {id}
""".stripMargin)
.on(
'name -> name,
'myClass -> myClass,
'custom -> id
).executeUpdate()
}
}
我还定义了一个从json到对象的隐式转换器
I also defined a implicit convertor from json to my object
implicit def columnToSocialData: Column[MyClass] = anorm.Column.nonNull[MyClass] { (value, meta) =>
val MetaDataItem(qualified, nullable, clazz) = meta
value match {
case json: org.postgresql.util.PGobject => {
val result = Json.fromJson[MyClass](Json.parse(json.getValue))
result.fold(
errors => Left(TypeDoesNotMatch(s"Cannot convert $value: ${value.asInstanceOf[AnyRef].getClass} to Json for column $qualified")),
valid => Right(valid)
)
}
case _ => Left(TypeDoesNotMatch(s"Cannot convert $value: ${value.asInstanceOf[AnyRef].getClass} to Json for column $qualified"))
}
我得到的错误是:
type mismatch;
found : (Symbol, Option[com.MyClass])
required: anorm.NamedParameter
'myClass -> myClass,
^
推荐答案
解决方案只是添加以下内容:
The solution is just to add the following:
implicit val socialDataToStatement = new ToStatement[MyClass] {
def set(s: PreparedStatement, i: Int, myClass: MyClass): Unit = {
val jsonObject = new org.postgresql.util.PGobject()
jsonObject.setType("json")
jsonObject.setValue(Json.stringify(Json.toJson(myClass)))
s.setObject(i, jsonObject)
}
}
和:
implicit object MyClassMetaData extends ParameterMetaData[MyClass] {
val sqlType = "OTHER"
val jdbcType = Types.OTHER
}
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