inamdarzaid opened a new pull request, #35014:
URL: https://github.com/apache/superset/pull/35014
# Multi-Page PDF Generation Implementation
## Overview
This implementation adds support for generating multi-page PDFs from table
data in Superset reports, replacing screenshot-based PDFs with HTML-to-PDF
conversion using WeasyPrint.
## Changes Made
### 1. Added WeasyPrint Dependency
**File**: `requirements/base.in`
- Added `weasyprint>=61.0` as a new dependency for HTML-to-PDF conversion
### 2. Enhanced PDF Utility Functions
**File**: `superset/utils/pdf.py`
Added new functions for HTML-to-PDF conversion:
- `generate_table_html()`: Converts pandas DataFrame to properly formatted
HTML
- Includes CSS for multi-page layout
- Adds page headers, footers, and page numbering
- Ensures table headers repeat on each page
- Provides professional styling
- `build_pdf_from_html()`: Converts HTML to PDF using WeasyPrint
- Handles WeasyPrint errors gracefully
- Returns PDF as bytes
- `build_pdf_from_dataframe()`: Complete workflow for DataFrame to PDF
- Combines HTML generation and PDF conversion
- Accepts title and description parameters
### 3. Modified Report Execution Logic
**File**: `superset/commands/report/execute.py`
Enhanced the `_get_pdf()` method:
- **Smart Detection**: Checks if the chart is a table type (`table`,
`pivot_table`, `pivot_table_v2`)
- **Full Data Access**: Uses `_get_embedded_data()` to get complete dataset
(not just visible data)
- **Multi-page Support**: Generates PDF from full data using HTML conversion
- **Graceful Fallback**: Falls back to screenshot-based PDF if data-based
generation fails
## Key Features
### 1. Complete Data Export
- Uses `embedded_data` which contains the full dataset from
`ChartDataResultFormat.JSON`
- Not limited to currently visible/paginated data in the UI
- Includes all rows regardless of frontend pagination
### 2. Professional Multi-Page Layout
- **Page Headers**: Repeat table headers on every page
- **Page Breaks**: Intelligent page breaking to avoid splitting rows
- **Page Numbers**: Automatic page numbering in footer
- **Styling**: Professional table formatting with alternating row colors
### 3. CSS Features for PDF
```css
@page {
size: A4;
margin: 2cm 1.5cm;
@bottom-center {
content: "Page " counter(page) " of " counter(pages);
}
}
/* Table headers repeat on each page */
.data-table thead {
display: table-header-group;
}
/* Prevent row breaks across pages */
.data-table tbody tr {
page-break-inside: avoid;
}
```
### 4. Error Handling
- Gracefully handles missing WeasyPrint installation
- Falls back to screenshot-based PDF generation on errors
- Provides detailed error logging
## Usage Flow
1. **Report Generation Request**: User requests PDF report for a table chart
2. **Chart Type Detection**: System checks if chart is table-based
3. **Data Retrieval**: `_get_embedded_data()` fetches complete dataset as
DataFrame
4. **HTML Generation**: DataFrame converted to HTML with multi-page CSS
5. **PDF Conversion**: WeasyPrint converts HTML to multi-page PDF
6. **Fallback**: If any step fails, falls back to screenshot-based PDF
## Benefits
### Before (Screenshot-based)
- ❌ Limited to visible data only
- ❌ Single page screenshots stitched together
- ❌ Poor text quality (image-based)
- ❌ Large file sizes
- ❌ No searchable text
### After (HTML-to-PDF)
- ✅ Complete dataset included
- ✅ True multi-page layout
- ✅ High-quality text rendering
- ✅ Smaller file sizes
- ✅ Searchable PDF content
- ✅ Professional page headers/footers
- ✅ Proper page breaking
## Installation Requirements
After these changes, you'll need to:
1. **Install WeasyPrint**: Run `pip install weasyprint>=61.0` or use the
updated requirements
2. **System Dependencies**: WeasyPrint may require system-level dependencies
(varies by OS)
## Compatibility
- **Backward Compatible**: Existing screenshot-based PDF generation remains
as fallback
- **Chart Types**: Currently enabled for `table`, `pivot_table`, and
`pivot_table_v2` charts
- **Other Charts**: Non-table charts continue using screenshot-based PDF
generation
## Future Enhancements
Potential improvements:
- Extend to other chart types with tabular data
- Add configuration options for PDF styling
- Support for custom page layouts
- Chart embedding alongside table data
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