Add custom javascript objects to chart?

Hii, I want to add some javascript object in all my chart. for instance I want to add `{"primary_key": "123A"}` . My plan is displaying the details from selected chart, execute some sql query and the parameter is come from the custom object that I need to add. Currently in the onclick callback I only got `onclick Object {id: "Proses", value: 81, ratio: 0.051071878940731355, index: 1, name: "Proses"}` and I need the callback returns `onclick Object {id: "Proses", value: 81, ratio: 0.051071878940731355, index: 1, name: "Proses", primary_key: "123A"}`

Thanks