Referencing output data schema from a StoreFunc

Hi,I would like to create a StoreFunc like MultiStorage but instead of referencing fields to be added to the output path by index, it references them by name (it would construct a map between names and indexes based on the schema of the data to be output). Is there a mechanism for a StoreFunc to access the schema of the data being stored? It looked like overriding checkSchema would do this, but it does not seem to be called in all cases.
Thank you,Rodrick