Well, what do you want to achieve in the first place?

# announcements

[stephanmg]

Well, what do you want to achieve in the first place?

[Rob Elliot]

I want to declare a statically type checked data structure in a way that mirrors as closely as possible the shape of the actual data that I can parse from XML/JSON/YAML/whatever .

[jef]

jackson should do this

[jef]

feel free to override any (de)serializers too with your data classes

[Rob Elliot]

There’s context just previously in the channel; I’m not asking about how to serialize/deserialize.

[jef]

statically type checked data structure in a way that mirrors as closely as possible the shape of the actual data

but serializing and deserializing would do this

[jef]

i'm sorry, but maybe i'm also missing the point. are you just wanting to use different syntax?

[Rob Elliot]

Yes.

[jef]

gotcha, one sec

[Rob Elliot]

More accurately I was suggesting a new syntax sugar that doesn’t currently exist - something like anonymous inner classes, or lambdas for SAM.

[jef]

ahh

[jef]

if you want something like this:

<a>
  <b>
    <c>
      <foo>"hello"</foo>
      <bar>45</bar>
    </c>
  </b>
</a>

you'd do something like this:

data class A(val b: B)
  data class B(val c: C)
  data class C(val foo: String, val bar: Int)

  @Test
  fun test() {
    val test = XmlMapper().writeValueAsString(A(B(C(foo = "test", bar = 42))))
    println(test)
  }

[jef]

you get this output from above:

<A><b><c><foo>test</foo><bar>42</bar></c></b></A>

[jef]

as with nested classes, you only get the last class you've initalized.

like this:

data class A(val b: B) {
    data class B(val c: C) {
      data class C(val foo: String, val bar: Int)
    }
  }

  @Test
  fun test() {
    val test = XmlMapper().writeValueAsString(A.B.C(foo = "test", bar = 42))
    println(test)
  }

gives an output of:

<C><foo>test</foo><bar>42</bar></C>

[jef]

but i do understand what you're saying.

[Rob Elliot]

Thanks, but I know how to use jackson to serialize to and from kotlin data classes.

[jef]

you could also do this... which is similar to your original post:

data class A(
      val b: Any = object {
        val c: Any = object {
          val foo: String = ""
          val bar: Int = 0
        }
      }
  )

  @Test
  fun test() {
    val test = XmlMapper().writeValueAsString(A())
    println(test)
  }

[jef]

that outputs:

<A><b><c><foo></foo><bar>0</bar></c></b></A>

[jef]

would be nice to declare data classes rather anonymous objects

[Rob Elliot]

The type of b & c is Any, so there’s no way to reference their properties. Fine for serializing to a data format, but no use for deserializing to kotlin values you want to use.

[jef]

very true.