TanStack Table version

v8.21.3

Framework/Library version

React v18.3.1

Describe the bug and the steps to reproduce it

When using TanStack Table with row selection and filtering, the table getIsSomeRowsSelected() function does not consistently return true when some visible rows are selected.

Steps to reproduce:

1. Create a table with row selection and filtering
2. Select several rows.
3. Apply a filter so only a subset of the selected rows are visible.
4. Click the header checkbox to select all of the filtered rows.
5. Begin unselecting the filtered rows from the top and observe that the header checkbox becomes unselected instead of indeterminate, indicating that getIsSomeRowsSelected() is returning false when it should be returning true.

This appears to be caused by the way the table.getIsSomeRowsSelected() is implemented. This is the current function implementation:

table.getIsSomeRowsSelected = () => {
  const totalSelected = Object.keys(
    table.getState().rowSelection ?? {}
  ).length
  return (
    totalSelected > 0 &&
    totalSelected < table.getFilteredRowModel().flatRows.length
  )
}

The issue with this approach is that it checks if the total number of selected rows (across the whole table, not just the filtered rows) is greater than 0 and less than the number of filtered rows. If you select rows that are filtered out, they will still count towards totalSelected. So if you have 3 visible rows and 2 selected (and also 2 more selected that are filtered out), totalSelected would be 4, which is greater than the number of visible rows (3), thus causing this function to return false, even though some filtered rows are selected.

Your Minimal, Reproducible Example - (Sandbox Highly Recommended)

https://tanstack.com/table/latest/docs/framework/react/examples/row-selection

Screenshots or Videos (Optional)

Do you intend to try to help solve this bug with your own PR?

Yes, I am also opening a PR that solves the problem along side this issue

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