Hi, In this link: https://github.com/svenvc/docs/blob/master/neo/neo-json-paper.md I see an example of a custom mapping like this one: mapper for: TestObject do: [ :mapping | mapping mapInstVars: #(id name). (mapping mapInstVar: #timestamp to: 'created-at') valueSchema: DateAndTime. (mapping mapInstVar: #points) valueSchema: #ArrayOfPoints. (mapping mapInstVar: #bytes) valueSchema: ByteArray ]. I need something similar, but I need to store the original JSON string that was used to build a particular TestObject instance, in an instance variable of TestObject too. In other words, I need an instVar "originalResponse" in TestObject that would be set with the original JSON string. Any ideas how can I implement this? Thanks in advance, -- Mariano http://marianopeck.wordpress.com