optimize file path

fet2020/finance/utils.py

@@ -1,6 +1,6 @@
 import io
-from pathlib import Path
 
+from django.contrib.staticfiles import finders
 from django.core.files import File
 from django.utils import timezone
 from pypdf import PdfReader, PdfWriter
@@ -55,8 +55,8 @@ def generate_pdf(wiref):
     )
 
     # Write data in pdf
-    pdf_path = Path(Path(__file__).parent) / "static/wiref/Vorlage.pdf"
-    reader = PdfReader(pdf_path)
+    pdf_path_str = finders.find("wiref/Vorlage.pdf")
+    reader = PdfReader(pdf_path_str)
     writer = PdfWriter()
     writer.append(reader)
 
@@ -74,6 +74,7 @@ def generate_pdf(wiref):
 
     with io.BytesIO() as bytes_stream:
         writer.write(bytes_stream)
+        bytes_stream.seek(0)
 
         # Save pdf in wiref
         wiref_name = f"Abrechnungsformular-{wiref.wiref_id}.pdf"