Hello Markus,
You need to use schema.parse option to change the data that you get from the server to the desired output it is documented here:
http://docs.telerik.com/kendo-ui/api/javascript/data/datasource#configuration-schema.parse
Please see the updated example:
http://dojo.telerik.com/oWABE/4
Regards,Kiril Nikolov
Telerik
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