kosiew opened a new issue, #1171:
URL: https://github.com/apache/datafusion-python/issues/1171
## Description:
Currently, DataFrameHtmlFormatter tracks a _styles_loaded class flag in
Python to avoid re-injecting styles and scripts across notebook cells. However,
this approach:
- Doesn’t survive module reloads or redefinitions
- Can conflict if multiple notebooks share the same kernel
- Still requires manual state resets in tests
We should move the “only-once” guard into the browser DOM/JS layer so that
every call to format_html can blindly emit the header scripts/styles, but the
browser will insert them only once per page.
## Proposed Change:
1. Remove the _styles_loaded class variable and related Python guard logic.
2. Always call _build_html_header() and _get_javascript() on each
format_html.
3. Inside those methods, wrap the CSS/JS in small <script> blocks that:
- Check document.getElementById('df-styles') (or a global flag) before
appending a <style> tag
- Check a window.__df_formatter_js_loaded__ flag before defining the toggle
function
### example snippet:
```python
--- a/python/datafusion/dataframe_formatter.py
+++ b/python/datafusion/dataframe_formatter.py
@@ -XXX,XX +XXX,XX @@ class DataFrameHtmlFormatter:
- # Class var: _styles_loaded = False
def _build_html_header(self) -> list[str]:
- html = []
- # Only include styles and scripts if needed
- if include_styles:
- html.extend(self._build_css_and_script())
- if self.use_shared_styles:
- DataFrameHtmlFormatter._styles_loaded = True
- return html
+ return ["""
<script>
// Only inject CSS once per page
if (!document.getElementById('df-styles')) {
const style = document.createElement('style');
style.id = 'df-styles';
style.textContent = `
/* DataFrameHtmlFormatter CSS… */
`;
document.head.appendChild(style);
}
</script>
"""] + ([f"<style>{self.custom_css}</style>"] if self.custom_css else [])
def _get_javascript(self) -> str:
- return """
-<script> …existing JS… </script>
-"""
+ return """
<script>
// Only inject toggle logic once
if (!window.__df_formatter_js_loaded__) {
window.__df_formatter_js_loaded__ = true;
window.toggleDataFrameCellText = function(table_uuid, row, col) {
/* …existing toggle logic… */
};
}
</script>
"""
```
## Benefits:
- Guaranteed “inject once” directly in the browser, regardless of Python
reloads
- Simplifies Python state—no _styles_loaded flag to manage
- Safe in multi-notebook or testing scenarios
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
---------------------------------------------------------------------
To unsubscribe, e-mail: [email protected]
For additional commands, e-mail: [email protected]
