PPTX Debug Workflow

PPTX Debugging Workflow

A systematic approach to creating and debugging PowerPoint presentations using the python-pptx library. This workflow ensures reliable presentation generation through iterative verification and error resolution.

Step 1: Verify Installation

Before writing any code, verify that python-pptx is installed:

pip show python-pptx

If not installed:

pip install python-pptx

Step 2: Test Minimal PPTX Creation

Create and run a minimal test script to verify the library works:

from pptx import Presentation

prs = Presentation()
slide = prs.slides.add_slide(prs.slide_layouts[0])
slide.shapes.title.text = "Test Slide"
prs.save("test.pptx")
print("Test presentation created successfully")

Run this first to confirm basic functionality before building complex presentations.

Step 3: Write Full Script to File

Always write your presentation script to a .py file instead of using heredoc or inline execution. This enables:

• Better error messages with line numbers
• Easier iteration and debugging
• Preserved state between error fixes

Example structure:

from pptx import Presentation
from pptx.util import Inches, Pt
from pptx.enum.shapes import MSO_SHAPE
from pptx.enum.chart import XL_CHART_TYPE, XL_LEGEND_POSITION
from pptx.chart.data import CategoryChartData

def create_presentation():
    prs = Presentation()
    # Build slides here
    prs.save("output.pptx")
    print("Presentation saved successfully")

if __name__ == "__main__":
    create_presentation()

Step 4: Execute and Capture Full Traceback

Run the script with full error output:

python your_script.py 2>&1 | tee debug_output.log

This captures the complete Python traceback including:

• Error type and message
• Line numbers where errors occurred
• Stack trace for debugging

Step 5: Fix API Errors Iteratively

Common python-pptx API patterns to remember:

Chart Legend Positioning

Use XL_LEGEND_POSITION (NOT XL_CHART_TYPE) for legend positioning:

from pptx.enum.chart import XL_LEGEND_POSITION

chart.chart.has_legend = True
chart.chart.legend.position = XL_LEGEND_POSITION.RIGHT

Table Cell Access

Access table cells through row iteration pattern:

table = slide.shapes.add_table(rows=5, cols=4, left=Inches(1), top=Inches(2), width=Inches(6), height=Inches(3)).table

# Correct pattern - iterate through rows, then cells
for row_idx, row in enumerate(table.rows):
    for cell_idx, cell in enumerate(row.cells):
        cell.text = f"Row {row_idx}, Cell {cell_idx}"

# Or direct access
table.rows[0].cells[0].text = "Header"

Chart Data Format

For pie charts, use category-based data:

chart_data = CategoryChartData()
chart_data.categories = ['Category A', 'Category B', 'Category C']
chart_data.add_series('Series 1', (30, 45, 25))

x, y, cx, cy = Inches(2), Inches(2), Inches(6), Inches(4.5)
slide.shapes.add_chart(XL_CHART_TYPE.PIE, x, y, cx, cy, chart_data)

Step 6: Validate Output

After successful execution:

1. Verify the .pptx file was created
2. Open in PowerPoint or compatible viewer
3. Check that all slides, tables, and charts render correctly

Common Troubleshooting

Quick Reference Script Template

from pptx import Presentation
from pptx.util import Inches, Pt
from pptx.enum.chart import XL_CHART_TYPE, XL_LEGEND_POSITION
from pptx.chart.data import CategoryChartData

def main():
    prs = Presentation()
    
    # Add title slide
    slide = prs.slides.add_slide(prs.slide_layouts[0])
    slide.shapes.title.text = "Title"
    
    # Add content slide with table
    slide = prs.slides.add_slide(prs.slide_layouts[1])
    table = slide.shapes.add_table(3, 3, Inches(1), Inches(2), Inches(8), Inches(2)).table
    for row in table.rows:
        for cell in row.cells:
            cell.text = "Data"
    
    prs.save("presentation.pptx")
    print("Done!")

if __name__ == "__main__":
    main()