MUI Data Grid Premium single grouped row selection

TableTest.js

import React, { useState } from 'react';
import { DataGridPremium, useGridApiRef, useKeepGroupedColumnsHidden } from '@mui/x-data-grid-premium';
import { useMovieData } from '@mui/x-data-grid-generator';

const TableTest = () => {
  const [selectionModel, setSelectionModel] = useState([]);
  const data = useMovieData();
  const apiRef = useGridApiRef();

  const initialState = useKeepGroupedColumnsHidden({
    apiRef,
    initialState: {
      rowGrouping: {
        model: ['company'],
      },
    },
  });

  return (
    <DataGridPremium
      {...data}
      autoHeight
      checkboxSelection
      disableSelectionOnClick
      apiRef={apiRef}
      rowGroupingColumnMode="single"
      initialState={initialState}
      selectionModel={selectionModel}
      onSelectionModelChange={selectedItems => {
        if(selectedItems.length === 0) {
          setSelectionModel([]);
        }
        if(selectedItems.length < selectionModel.length) {
          let removedItems = selectionModel.filter(itm => !selectedItems.includes(itm));
          removedItems.map(id => {
            if(`${id}`.indexOf('auto-generated-row-') === 0) {
              // deselect group children
              let children = apiRef.current.getRowGroupChildren({groupId: id});
              selectedItems = selectedItems.filter(itm => !children.includes(itm));
            } else {
              // deselect parent
              let groupingColumn = apiRef.current.state.rowGrouping.model[0];
              if(apiRef.current.getRow(id)) {
                let childValue = apiRef.current.getRow(id)[groupingColumn];
                selectedItems = selectedItems.filter(itm => itm !== `auto-generated-row-${groupingColumn}/${childValue}`);
              }
            }
          })
        } else {
          selectedItems = selectedItems.flatMap(id => {
            if(`${id}`.indexOf('auto-generated-row-') === 0) {
              // select row group children
              let children = apiRef.current.getRowGroupChildren({groupId: id});
              return [...children, id];
            } else {
              return id;
            }
          })
        }
        // Set() removes duplicate rows
        setSelectionModel([...new Set(selectedItems)])
      }}
    />
  );
}

export default TableTest;

@jarrisoncano you are absolutely right I forgot to add that part. Unfortunately my project no longer needs this functionality so I haven't had time to do any updates to this. If you figure out a solution let me know though!

i just find a method in the documentiation for filter the childrens that match with the currentFilters

https://mui.com/x/react-data-grid/row-grouping/#get-the-rows-in-a-group