Match JSON POST data with custom node fields

Question

Is there a fool-proof method to generate a correctly formatted JSON data object to be received by a create node resource given by a REST server, defined with Services in Drupal 7?

I have setup a REST server accepting the application/json content type. I have also set up an anonymous endpoint with the create node resource enabled and I managed to create a new item with the Poster plugin for Firefox with Content Type set to application/json and the following data

{"title":"Review","type":"story"}

I can't seem to get any further though. I am following this guide and the node is created but my data for the rest of the fields is not added. I use this JSON editor to generate my code so it matches the structure shown by the dsm($_POST) call I placed in node.module's node_submit handler for testing.

The JSON data I am trying to post looks like this (I remove all whitespace before using Poster):

{
"title":"great success!",
"type":"story",
"field_review":[
    {"und":
        [{"0":
            [
                {"value":"Some text"}
            ]
        }]
    }
],
"field_rating":[
    {"und":
        [
            {"rating":"60"}
        ]
    }
],
"field_product_type":[
    {"und": "1"}
],
"field_barcode":[
    {"und":
        [
            {"value":"33333333333"}
        ]
    }
]
}

What am I missing?