From 4bdca1628606706f652f02c260c2e7dd53fb2ff7 Mon Sep 17 00:00:00 2001
From: pubpub-zz <4083478+pubpub-zz@users.noreply.github.com>
Date: Tue, 2 Apr 2024 18:43:49 +0200
Subject: [PATCH] ENH: Allow to update fields on many pages (#2571)

---
 pypdf/_writer.py     | 14 ++++++++++++--
 tests/test_writer.py | 17 +++++++++++------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/pypdf/_writer.py b/pypdf/_writer.py
index 88e280ee5..06f38b03b 100644
--- a/pypdf/_writer.py
+++ b/pypdf/_writer.py
@@ -896,7 +896,7 @@ def _update_field_annotation(
 
     def update_page_form_field_values(
         self,
-        page: PageObject,
+        page: Union[PageObject, List[PageObject], None],
         fields: Dict[str, Any],
         flags: FieldFlag = OPTIONAL_READ_WRITE_FIELD,
         auto_regenerate: Optional[bool] = True,
@@ -908,8 +908,10 @@ def update_page_form_field_values(
         If the field links to a parent object, add the information to the parent.
 
         Args:
-            page: Page reference from PDF writer where the
+            page: `PageObject` - references **PDF writer's page** where the
                 annotations and field data will be updated.
+                `List[Pageobject]` - provides list of page to be processsed.
+                `None` - all pages.
             fields: a Python dictionary of field names (/T) and text
                 values (/V).
             flags: An integer (0 to 7). The first bit sets ReadOnly, the
@@ -925,6 +927,14 @@ def update_page_form_field_values(
             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 page is None:
+            page = list(self.pages)
+        if isinstance(page, list):
+            for p in page:
+                if PG.ANNOTS in p:  # just to prevent warnings
+                    self.update_page_form_field_values(p, fields, flags, None)
+            return None
         if PG.ANNOTS not in page:
             logger_warning("No fields to update on this page", __name__)
             return
diff --git a/tests/test_writer.py b/tests/test_writer.py
index baf0134e2..6ff45c3eb 100644
--- a/tests/test_writer.py
+++ b/tests/test_writer.py
@@ -1504,14 +1504,20 @@ def test_update_form_fields(tmp_path):
         page_number=0,
         annotation=Link(target_page_index=1, rect=RectangleObject([0, 0, 100, 100])),
     )
+    writer.insert_blank_page(100, 100, 0)
     del writer.root_object["/AcroForm"]["/Fields"][1].get_object()["/DA"]
     del writer.root_object["/AcroForm"]["/Fields"][1].get_object()["/DR"]["/Font"]
     writer.update_page_form_field_values(
-        writer.pages[0],
+        [writer.pages[0], writer.pages[1]],
+        {"Text1": "my Text1", "Text2": "ligne1\nligne2\nligne3"},
+        auto_regenerate=False,
+    )
+    assert b"/Helv " in writer.pages[1]["/Annots"][1]["/AP"]["/N"].get_data()
+    writer.update_page_form_field_values(
+        None,
         {"Text1": "my Text1", "Text2": "ligne1\nligne2\nligne3"},
         auto_regenerate=False,
     )
-    assert b"/Helv " in writer.pages[0]["/Annots"][1]["/AP"]["/N"].get_data()
 
     Path(write_data_here).unlink()
 
@@ -1568,10 +1574,9 @@ def test_update_form_fields2():
         reader.add_form_topname(file)
         writer = PdfWriter(clone_from=reader)
 
-        for page in writer.pages:
-            writer.update_page_form_field_values(
-                page, myFiles[file]["usage"]["fields"], auto_regenerate=True
-            )
+        writer.update_page_form_field_values(
+            None, myFiles[file]["usage"]["fields"], auto_regenerate=True
+        )
         merger.append(writer)
     assert merger.get_form_text_fields(True) == {
         "test1.First Name": "Reed",