lift-json操纵 - 添加到正确的位置

Question

考虑以下json:

{
  "type":"A1",
  "system":{
    "path":"/example.org/FooBar",
    "lastModified":"2013-10-01T12:00:00Z"
  },
  "fields":{
    "foo1":["bar1"],
    "foo2":["bar2"],
    "foo3":["bar3"]
  }
}

现在,使用lift-json,我想将此json更改为:

{
  "type":"A1",
  "system":{
    "path":"/example.org/FooBar",
    "lastModified":"2013-10-01T12:00:00Z"
  },
  "fields":{
    "foo1":["bar1"],
    "foo2":["bar2"],
    "foo3":["bar3"]
  },
  "injected":{
    "bar1":"foo1",
    "bar2":"foo2"
  }
}

所以,我尝试了以下内容:

scala> val json = parse("""
     |{
     |  "type":"A1",
     |  "system":{
     |    "path":"/example.org/FooBar",
     |    "lastModified":"2013-10-01T12:00:00Z"
     |  },
     |  "fields":{
     |    "foo1":["bar1"],
     |    "foo2":["bar2"],
     |    "foo3":["bar3"]
     |  }
     |}""")

json: net.liftweb.json.JValue = JObject(List(JField(type,JString(A1)), JField(system,JObject(List(JField(path,JString(/example.org/FooBar)), JField(lastModified,JString(2013-10-01T12:00:00Z))))), JField(fields,JObject(List(JField(foo1,JArray(List(JString(bar1)))), JField(foo2,JArray(List(JString(bar2)))), JField(foo3,JArray(List(JString(bar3)))))))))

scala> json transform{case JObject(l) => JObject(l ::: List(JField("injected", ("bar1" -> "foo1") ~ ("bar2" -> "foo2"))))}
res0: net.liftweb.json.JsonAST.JValue = JObject(List(JField(type,JString(A1)), JField(system,JObject(List(JField(path,JString(/example.org/FooBar)), JField(lastModified,JString(2013-10-01T12:00:00Z)), JField(injected,JObject(List(JField(bar1,JString(foo1)), JField(bar2,JString(foo2)))))))), JField(fields,JObject(List(JField(foo1,JArray(List(JString(bar1)))), JField(foo2,JArray(List(JString(bar2)))), JField(foo3,JArray(List(JString(bar3)))), JField(injected,JObject(List(JField(bar1,JString(foo1)), JField(bar2,JString(foo2)))))))), JField(injected,JObject(List(JField(bar1,JString(foo1)), JField(bar2,JString(foo2)))))))

scala> Printer.pretty(render(res0))
res1: String = 
{
  "type":"A1",
  "system":{
    "path":"/example.org/FooBar",
    "lastModified":"2013-10-01T12:00:00Z",
    "injected":{
      "bar1":"foo1",
      "bar2":"foo2"
    }
  },
  "fields":{
    "foo1":["bar1"],
    "foo2":["bar2"],
    "foo3":["bar3"],
    "injected":{
      "bar1":"foo1",
      "bar2":"foo2"
    }
  },
  "injected":{
    "bar1":"foo1",
    "bar2":"foo2"
  }
}

正如你所看到的,这个injected部分也加入了fields&system.我只想在根目录下添加一次.

那么,我做错了什么？如何将json转换为我需要的正确结构？

Answer 1

您遇到的问题是转换中定义的部分函数在json结构中的所有可能级别上都匹配.由于外部JObject的"系统"和"字段"组件本身就是JObject,它们与部分函数匹配,并且也可以进行转换.

要获得您正在寻找的结果,您需要使匹配更具体,例如:

json transform {case JObject(fields) if (fields contains JField("type", "A1")) =>
   JObject(l ::: ...

使用关于最外层对象的一些独特信息(这里,它将"type"设置为"A1").

另外,lift json有一个我没有处理的合并功能,但可能会提供你想要的东西:

json merge JObject(JField("injected", ...) :: Nil)