coverage

pypdf/_writer.py

@@ -939,17 +939,17 @@ def update_page_form_field_values(
             auto_regenerate: set/unset the need_appearances flag ;
                 the flag is unchanged if auto_regenerate is None
         """
+        if CatalogDictionary.ACRO_FORM not in self._root_object:
+            raise PyPdfError("No /AcroForm dictionary in PdfWriter Object")
+        af = cast(DictionaryObject, self._root_object[CatalogDictionary.ACRO_FORM])
+        if InteractiveFormDictEntries.Fields not in af:
+            raise PyPdfError("No /Fields dictionary in Pdf in PdfWriter Object")
         if isinstance(auto_regenerate, bool):
             self.set_need_appearances_writer(auto_regenerate)
         # Iterate through pages, update field values
         if PG.ANNOTS not in page:
             logger_warning("No fields to update on this page", __name__)
             return
-        if CatalogDictionary.ACRO_FORM not in self._root_object:
-            raise PyPdfError("No /AcroForm dictionary in PdfWriter Object")
-        af = cast(DictionaryObject, self._root_object[CatalogDictionary.ACRO_FORM])
-        if InteractiveFormDictEntries.Fields not in af:
-            raise PyPdfError("No /Fields dictionary in Pdf in PdfWriter Object")
         # /Helvetica is just in case of but this is normally insufficient as we miss the font ressource
         default_da = af.get(
             InteractiveFormDictEntries.DA, TextStringObject("/Helvetica 0 Tf 0 g")

tests/test_writer.py

@@ -13,7 +13,7 @@
     PdfWriter,
     Transformation,
 )
-from pypdf.errors import DeprecationError, PageSizeNotDefinedError
+from pypdf.errors import DeprecationError, PageSizeNotDefinedError, PyPdfError
 from pypdf.generic import (
     ArrayObject,
     ContentStream,
@@ -1508,3 +1508,25 @@ def test_da_missing_in_annot():
     fields = reader.get_form_text_fields()
     fields["PCN-1"] = "0"
     writer.update_page_form_field_values(writer.pages[0], fields)
+
+
+def test_missing_fields(pdf_file_path):
+    reader = PdfReader(RESOURCE_ROOT / "form.pdf")
+
+    writer = PdfWriter()
+    writer.add_page(reader.pages[0])
+
+    with pytest.raises(PyPdfError) as exc:
+        writer.update_page_form_field_values(
+            writer.pages[0], {"foo": "some filled in text"}, flags=1
+        )
+    assert exc.value.args[0] == "No /AcroForm dictionary in PdfWriter Object"
+
+    writer = PdfWriter()
+    writer.append(reader, [0])
+    del writer._root_object["/AcroForm"]["/Fields"]
+    with pytest.raises(PyPdfError) as exc:
+        writer.update_page_form_field_values(
+            writer.pages[0], {"foo": "some filled in text"}, flags=1
+        )
+    assert exc.value.args[0] == "No /Fields dictionary in Pdf in PdfWriter Object"