More advanced example of a custom spray-json format

customformat.scala

  implicit object ProductItemFormat extends RootJsonFormat[ProductItem] {
    // some fields are optional so we produce a list of options and
    // then flatten it to only write the fields that were Some(..)
    def write(item: ProductItem) = JsObject(
      List(
        Some("product_number" -> item.productNumber.toJson),
        item.ean.map(ean ⇒ "ean" -> ean.toJson),
        Some("title" -> item.title.toJson),
        item.description.map(description ⇒ "description" -> description.toJson),
        Some("price" -> item.price.toJson),
        Some("original_price" -> item.originalPrice.toJson),
        item.scratchPrice.map(scratchPrice ⇒ "scratch_price" -> scratchPrice.toJson),
        Some("scratch_price_to_display" -> item.scratchPriceToDisplay.toJson), // calculated field used by the UI
        Some("size" -> item.size.toJson),
        Some("availableStock" -> item.availableStock.toJson),
        Some("shipping" -> item.shipping.toJson),
        Some("vat_code" -> item.vatCode.toJson),
        Some("vat_percentage" -> item.vatPercentage.toJson)
      ).flatten: _*
    )

    // we use the "standard" getFields method to extract the mandatory fields. 
    // For optional fields we extract them directly from the fields map using get, 
    // which already handles the option wrapping for us so all we have to do is map the option
    def read(json: JsValue) = {
      val jsObject = json.asJsObject

      jsObject.getFields("product_number", "title", "price", "original_price", "size", "availableStock", "shipping", "vat_code", "vat_percentage") match {
        case Seq(number, title, price, originalPrice, size, availableStock, shipping, vatCode, vatPercentage) ⇒ ProductItem(
          number.convertTo[String],
          jsObject.fields.get("ean").map(_.convertTo[String]),
          title.convertTo[String],
          jsObject.fields.get("description").map(_.convertTo[String]),
          price.convertTo[Int],
          originalPrice.convertTo[Int],
          jsObject.fields.get("scratch_price").map(_.convertTo[Int]),
          size.convertTo[Size], // notice that this just works (TM) as long as the required json format is implicitly available
          availableStock.convertTo[Int],
          shipping.convertTo[ShippingInfo], // notice that this just works (TM) as long as the required json format is implicitly available
          vatCode.convertTo[String],
          vatPercentage.convertTo[Int]
        )
        case other ⇒ deserializationError("Cannot deserialize ProductItem: invalid input. Raw input: " + other)
      }
    }
  }

Can you please give the sample json that goes with this? It will help us in understanding . Thanks .