📝 Summary

mo.ui.dataframe was displaying "0 columns" in the footer, even though the data rendered correctly. After applying transforms like "Select Columns", the column count also didn't update to reflect the filtered columns.

🔍 Description of Changes

The column count was being calculated using Object.keys(columns).length but because it is a Map, .keys() returns an empty array, and hence the zero length. Updated to use field_types.length from the get_dataframe() response instead. This correctly reflects the actual columns being displayed, including after transforms are applied.

Screenshot

Before

After

Note: I've not added any specific tests for this, since it's a minor bug fix.

📋 Checklist

• I have read the contributor guidelines.
• For large changes, or changes that affect the public API: this change was discussed or approved through an issue, on Discord, or the community discussions (Please provide a link if applicable).
• Tests have been added for the changes made.
• Documentation has been updated where applicable, including docstrings for API changes.
• Pull request title is a good summary of the changes - it will be used in the release notes.