having placeholder groupby rows for empty arrays when grouping

[tmax22]

Assume I have Persons which have links to favorite Colors.

The rows are built in such a way that each link between a person and a color gets a row. So, if a Person named Mike has 3 favorite colors, I will add 3 rows to the table.

The Row definition would be similar to:

interface Row {
  person_name: string;
  favorite_color: string;
}

I want each person to have their own grouped row always, even if there are currently no links between the Person and a color.

examples

Example 1: Both Mike and Steve have favorite colors

In this example, Mike has three favorite colors and Steve has two favorite colors.

const Rows: Row[] = [
  { person_name: "Mike", favorite_color: "Red" },
  { person_name: "Mike", favorite_color: "Blue" },
  { person_name: "Mike", favorite_color: "Green" },
  { person_name: "Steve", favorite_color: "Yellow" },
  { person_name: "Steve", favorite_color: "Purple" }
];

both Mike and Steve have dedicated grouped row that is expandable to see their favorite colors.

Example 2: Only Mike has favorite colors, Steve does not

In this example, Mike has three favorite colors and Steve does not have any explicit rows for favorite colors

const Rows: Row[] = [
  { person_name: "Mike", favorite_color: "Red" },
  { person_name: "Mike", favorite_color: "Blue" },
  { person_name: "Mike", favorite_color: "Green" }
];

and this example, Steve doesn't get it's owned row because there is no currently data associated with him.
I wish that Steve would get it's own grouped row with zero rows on the 'expanding' section of the row. because i know there is such a person and i've added an Add button on the AggregatedCell, and if there is no link, so there's no grouping for Steve and the AggregatedCell would never appears.

wanted solution: another option, maybe something like mandatoryGroupingRows. in this example mandatoryGroupingRows would be equal ["Steve","Mike"].

another option would be providing a solid way to override the grouping state. then i could just provide me wanted grouped rows and the rows that associated with each group. i saw manualGrouping option discussion but it seems like a 'Not yet implemented' option.

[tmax22]

update: i was able to implement it in my own fork. but it evolves overriding getGroupedRowModel and also patching cell.getIsAggregated to remove check for 0 length subrows.

see details here.