[data grid] Grouped column with empty Header exports to Excel with __row_group_by_columns_group__ name

[rettoua]

Duplicates

• I have searched the existing issues

Latest version

• I have tested the latest version

Steps to reproduce 🕹

Link to live example:
https://codesandbox.io/s/immutable-cherry-51xoxo?file=/demo.tsx

Steps:

1. Open the example and click on the Export button.
2. Open exported Excel file

Current behavior 😯

there is __row_group_by_columns_group__ header for grouped column

Expected behavior 🤔

Grouped column header must be the same as set in the groupingColDef options

Context 🔦

No response

Your environment 🌎

npx @mui/envinfo

   System:
    OS: macOS 13.0
  Binaries:
    Node: 16.13.2 - /usr/local/bin/node
    Yarn: 1.22.19 - /opt/homebrew/bin/yarn
    npm: 8.1.2 - /usr/local/bin/npm
  Browsers:
    Chrome: 107.0.5304.121
  npmPackages:
    @emotion/react: ~11.10.0 => 11.10.4 
    @emotion/styled: ~11.10.0 => 11.10.4 
    @mui/base:  5.0.0-alpha.79 
    @mui/icons-material: ~5.8.4 => 5.8.4 
    @mui/lab: 5.0.0-alpha.80 => 5.0.0-alpha.80 
    @mui/material: ~5.6.4 => 5.6.4 
    @mui/private-theming:  5.10.6 
    @mui/styled-engine:  5.10.7 
    @mui/styles: ~5.6.2 => 5.6.2 
    @mui/system:  5.10.7 
    @mui/types:  7.2.0 
    @mui/utils:  5.10.6 
    @mui/x-data-grid: ~5.17.12 => 5.17.12 
    @mui/x-data-grid-premium: ~5.17.12 => 5.17.12 
    @mui/x-data-grid-pro: ~5.17.12 => 5.17.12 
    @mui/x-date-pickers: ~5.0.0-beta.4 => 5.0.3 
    @mui/x-license-pro:  5.17.12 
    @types/react: ~18.0.21 => 18.0.21 
    react: ~17.0.2 => 17.0.2 
    react-dom: ~17.0.2 => 17.0.2 
    typescript: ~4.6.4 => 4.6.4 

Order ID 💳 (optional)

54867

[yaredtsy]

hey @rettoua
when you create columns if headerName is empty it uses the field as the headerName. __row_group_by_columns_group__ is the filed name of the column. if you want it to be empty you can use space

[rettoua]

hi @yaredtsy the component needs to be consistent in its functionality, if empty headerName works in js it also must work while exporting. I spent quite some time figuring out what is wrong and came to the same conclusion that you've mentioned: use space, but it shouldn't be that way.

[alexfauquette]

Effectively, it's a problem of using || instead of ?? in the excel export