After a fair amount of work, I managed to use pivots to format my data in such a way that it would be far more efficient for use in my custom visualisation. Custom visualisations receive a JSON-formatted chunk of data from the server, typically organised in rows.
Whilst doing this legwork, I tried to see what would come from my efforts by using the ‘Download’ option on the Look, then viewing the resulting JSON. Everything looked fine, with a wonderfully nested structure matching the pivots on the table in the Look UI.
However, once I checked to see what my custom visualisation was receiving, I was shocked to discover that that data looked nothing like the downloaded sample; most of the nested structure was absent, replaced with flat row sets with utterly unexpected value naming.
Is there any way to get JSON sent to my visualisation that matches the structure shown when i choose to download a sample??