Excluded sub-component id in newState when handling selection in Table

.changeset/strange-rockets-taste.md

@@ -0,0 +1,5 @@
+---
+'@itwin/itwinui-react': patch
+---
+
+Fixed duplicate data returned from the `onSelect` prop passed into `Table`.

packages/itwinui-react/src/core/Table/Table.test.tsx

@@ -1981,6 +1981,44 @@ it('should select and filter rows', async () => {
   expect(checkboxInputs[3].checked).toBe(false);
 });
 
+it('should only select main row when subComponent is present', async () => {
+  const logSpy = vitest.spyOn(console, 'log');
+  const columns = [
+    {
+      id: 'name',
+      Header: 'Name',
+      accessor: 'name',
+    },
+    {
+      id: 'description',
+      Header: 'description',
+      accessor: 'description',
+    },
+  ];
+
+  const data = mockedData();
+
+  const { container } = renderComponent({
+    columns,
+    data,
+    isSelectable: true,
+    onSelect: (selectedRows) => console.log(selectedRows),
+    subComponent: (row) => <div>{`Name ${row.original.name}`}</div>,
+  });
+
+  const checkboxCells = container.querySelectorAll('.iui-slot .iui-checkbox');
+  expect(checkboxCells.length).toBe(4);
+
+  await userEvent.click(checkboxCells[0]);
+  expect(logSpy).toHaveBeenCalledWith(data);
+
+  await userEvent.click(checkboxCells[1]);
+  expect(logSpy).toHaveBeenCalledWith([data[1], data[2]]);
+
+  await userEvent.click(checkboxCells[2]);
+  expect(logSpy).toHaveBeenCalledWith([data[2]]);
+});
+
 it('should pass custom props to row', () => {
   const onMouseEnter = vi.fn();
   let element: HTMLInputElement | null = null;

packages/itwinui-react/src/core/Table/Table.tsx

@@ -71,7 +71,7 @@ const singleRowSelectedAction = 'singleRowSelected';
 const shiftRowSelectedAction = 'shiftRowSelected';
 export const tableResizeStartAction = 'tableResizeStart';
 const tableResizeEndAction = 'tableResizeEnd';
-const iuiId = Symbol('iui-id');
+export const iuiId = Symbol('iui-id');
 
 export type TablePaginatorRendererProps = {
   /**

packages/itwinui-react/src/core/Table/actionHandlers/selectHandler.ts

@@ -9,6 +9,7 @@ import type {
   TableState,
   IdType,
 } from '../../../react-table/react-table.js';
+import { iuiId } from '../Table.js';
 
 /**
  * Handles subrow selection and validation.
@@ -38,20 +39,24 @@ const onSelectHandler = <T extends Record<string, unknown>>(
     }
 
     let isAllSubSelected = true;
-    row.initialSubRows.forEach((subRow) => {
-      const result = handleRow(subRow);
-      if (!result) {
-        isAllSubSelected = false;
-      }
-    });
-
-    // If `selectSubRows` is false, then no need to select sub-rows and just check current selection state.
-    // If a row doesn't have sub-rows then check its selection state.
-    // If it has sub-rows then check whether all of them are selected.
+    if (row.initialSubRows[0]?.original[iuiId as any] === undefined) {
+      row.initialSubRows.forEach((subRow) => {
+        const result = handleRow(subRow);
+        if (!result) {
+          isAllSubSelected = false;
+        }
+      });
+    }
+
+    // A row is considered selected if it is selected AND one of the following:
+    // - `selectSubRows` is false, OR
+    // - the row has no sub-rows, OR
+    // - the row has sub-rows and all of them are selected
     if (
-      (!instance.selectSubRows && newState.selectedRowIds[row.id]) ||
-      (!row.initialSubRows.length && newState.selectedRowIds[row.id]) ||
-      (row.initialSubRows.length && isAllSubSelected)
+      newState.selectedRowIds[row.id] &&
+      (!instance.selectSubRows ||
+        !row.initialSubRows.length ||
+        isAllSubSelected)
     ) {
       newSelectedRowIds[row.id as IdType<T>] = true;
     }

packages/itwinui-react/src/core/Table/columns/selectionColumn.tsx

@@ -10,6 +10,7 @@ import type {
 } from '../../../react-table/react-table.js';
 import { Checkbox } from '../../Checkbox/Checkbox.js';
 import { DefaultCell } from '../cells/index.js';
+import { iuiId } from '../Table.js';
 
 export const SELECTION_CELL_ID = 'iui-table-checkbox-selector';
 
@@ -82,7 +83,12 @@ export const SelectionColumn = <T extends Record<string, unknown>>(
         disabled={isDisabled?.(row.original)}
         onClick={(e) => e.stopPropagation()} // Prevents triggering on row click
         onChange={() => {
-          if (row.subRows.length > 0 && selectSubRows) {
+          // Only goes through sub-rows if they are available and not sub-components
+          if (
+            row.subRows.length > 0 &&
+            selectSubRows &&
+            row.initialSubRows[0].original[iuiId as any] === undefined
+          ) {
             //This code ignores any sub-rows that are not currently available(i.e disabled or filtered out).
             //If all available sub-rows are selected, then it deselects them all, otherwise it selects them all.
             row.toggleRowSelected(