Indeed, but is this worse than flattening all rows at once when the table renders initially ? 

Maybe the code could refactored much more so that it flattens all rows when needed, once, when opening the fields list, showing a row as a table, or micro-analysing a facet. And still, we don't need to flatten all rows when just showing a single row as a table

Right now, my knowledge of angular is pretty much experimental, hence the bad practice result :/ What's your opinion ?