feat: Add PDF form filler script for AcroForm fields

Add Python script to automatically fill PDF forms with AcroForm fields:
- extract_fields(): Extract all form field names and types from PDF
- fill_pdf(): Fill PDF with values from JSON input
- Support for both list and dict JSON formats
- Checkbox values support (/On, /Off, /Ja, /Nein)

https://claude.ai/code/session_01Dq1f9hjJFq859ShW2kZ26R

fill_pdf.py

@@ -0,0 +1,95 @@
+#!/usr/bin/env python3
+"""
+PDF Form Filler - Automatisches Ausfüllen von PDF-Formularen mit AcroForm-Feldern.
+
+Usage:
+    python fill_pdf.py <input.pdf> <values.json> <output.pdf>
+    python fill_pdf.py --extract <input.pdf>  # Extrahiert Feldnamen
+"""
+
+from pypdf import PdfReader, PdfWriter
+import json
+import sys
+
+
+def extract_fields(pdf_path: str) -> list[dict]:
+    """Extrahiert alle Formularfelder aus einer PDF."""
+    reader = PdfReader(pdf_path)
+    fields = reader.get_fields()
+
+    if not fields:
+        return []
+
+    result = []
+    for field_name, field_data in fields.items():
+        field_type = field_data.get('/FT', '')
+        field_info = {
+            "field_id": field_name,
+            "type": str(field_type),
+            "value": field_data.get('/V', '')
+        }
+        result.append(field_info)
+
+    return result
+
+
+def fill_pdf(input_pdf: str, field_values: dict, output_pdf: str):
+    """
+    Befüllt eine PDF mit den angegebenen Feldwerten.
+
+    field_values Format:
+    {
+        "txtName": "Max Mustermann",
+        "txtDatum": "28.01.2025",
+        "chkOption": "/Ja"  # Checkboxen: /On, /Off, /Ja, /Nein
+    }
+    """
+    reader = PdfReader(input_pdf)
+    writer = PdfWriter()
+    writer.append(reader)
+
+    # Felder auf allen Seiten befüllen
+    for page_num in range(len(writer.pages)):
+        writer.update_page_form_field_values(
+            writer.pages[page_num],
+            field_values
+        )
+
+    with open(output_pdf, "wb") as output:
+        writer.write(output)
+
+
+def main():
+    # Extraktionsmodus
+    if len(sys.argv) == 3 and sys.argv[1] == "--extract":
+        pdf_path = sys.argv[2]
+        fields = extract_fields(pdf_path)
+        print(json.dumps(fields, indent=2, ensure_ascii=False))
+        return
+
+    # Normaler Füllmodus
+    if len(sys.argv) != 4:
+        print("Usage: python fill_pdf.py <input.pdf> <values.json> <output.pdf>")
+        print("       python fill_pdf.py --extract <input.pdf>")
+        sys.exit(1)
+
+    input_pdf = sys.argv[1]
+    values_json = sys.argv[2]
+    output_pdf = sys.argv[3]
+
+    # JSON laden
+    with open(values_json, 'r', encoding='utf-8') as f:
+        data = json.load(f)
+
+    # Wenn Liste: in Dict umwandeln
+    if isinstance(data, list):
+        field_values = {item['field_id']: item['value'] for item in data}
+    else:
+        field_values = data
+
+    fill_pdf(input_pdf, field_values, output_pdf)
+    print(f"PDF erfolgreich erstellt: {output_pdf}")
+
+
+if __name__ == "__main__":
+    main()

requirements.txt

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+pypdf>=4.0.0