[data grid] Grid crashes when grouping by date column using valueGetter

[BiserZIvanov]

Steps to reproduce

Steps:

1. Open this link to live example: live demo
2. Group by the dateCreated column.
3. Then group by the company column.
4. Expand any grouped row.

Current behavior

App crashes with the following error:
MUI X: datecolumn type only acceptsDateobjects as values. UsevalueGetterto transform the value into aDate object. Row ID: auto-generated-row-dateCreated/Wed Jan 12 2022 18:36:23 GMT+0200 (Eastern European Standard Time)-company/20th Century Fox, field: "dateCreated".

Expected behavior

Grouped rows expand normally.

Context

I'm building a data grid that groups rows by multiple columns, including a date field. The date field is stored as an ISO string in the dataset and is converted to a Date object using a valueGetter, as recommended for type: "date" columns. However, when grouping by this date column, the grid crashes due to the grouping logic not respecting the valueGetter result. I'm trying to implement hierarchical grouping (e.g., Date → Company) without needing to mutate the original data or duplicate values.

Your environment

npx @mui/envinfo

Reproduced in CodeSandbox: https://codesandbox.io/p/sandbox/z24lgh

Environment Info:

• OS: CodeSandbox (cloud)
• Browser: Tested in Chrome 137
• @mui/material: 7.1.2
• @mui/x-data-grid-premium: 8.5.3
• react: 18.2.0

Search keywords: DataGridPremium, rowGrouping, group by date, valueGetter, type: date, Date object error, MUI X, column grouping, crash on expand, auto-generated-row

Order ID: 96739

[michelengelen]

I can confirm this bug.
It is a bit weird that this occurs though. Adding to the board!

[cherniavskii]

Fixed by #18967

https://stackblitz.com/edit/lqvaqftv?file=src%2FDemo.tsx

[github-actions]

This issue has been closed. If you have a similar problem but not exactly the same, please open a new issue.
Now, if you have additional information related to this issue or things that could help future readers, feel free to leave a comment.

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