From 9e524493aee2791a2a0db33097d364a966698bf6 Mon Sep 17 00:00:00 2001
From: deepakganesh78 <deepakganesh78@users.noreply.github.com>
Date: Sun, 2 Aug 2026 22:27:24 +0530
Subject: [PATCH] Fix dynamic column callable placeholders

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
---
 AUTHORS              | 1 +
 HISTORY.md           | 5 +++++
 src/tablib/core.py   | 8 +++++++-
 tests/test_tablib.py | 9 ++++++---
 4 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index cd73e6574..218b1b2f5 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -10,6 +10,7 @@ Here is a list of past and present much-appreciated contributors:
     Bruno Soares
     Claude Paroz
     Daniel Santos
+    Deepak Ganesh
     Egor Osokin
     Erik Youngren
     Hugo van Kemenade
diff --git a/HISTORY.md b/HISTORY.md
index 77f3b6b34..858518e4e 100644
--- a/HISTORY.md
+++ b/HISTORY.md
@@ -2,6 +2,11 @@
 
 ## 3.9.0 and newer
 
+### Bugfixes
+
+- Resolve dynamic column callables supplied as row placeholders when appending
+  rows (#576).
+
 See GitHub Releases:
 
 - https://github.com/jazzband/tablib/releases
diff --git a/src/tablib/core.py b/src/tablib/core.py
index b0b56fd23..6ef49b39c 100644
--- a/src/tablib/core.py
+++ b/src/tablib/core.py
@@ -458,10 +458,16 @@ def insert(self, index, row, tags=()):
         :class:`Dataset` later.
         """
 
+        row = list(row)
+        if len(row) == self.width:
+            for pos, func in sorted(self._dynamic_columns.items()):
+                if pos < len(row) and row[pos] is func:
+                    source_row = row[:pos] + row[pos + 1:]
+                    row[pos] = func(source_row)
+
         self._validate(row)
         if len(row) < self.width:
             for pos, func in self._dynamic_columns.items():
-                row = list(row)
                 row.insert(pos, func(row))
         self._data.insert(index, Row(row, tags=tags))
 
diff --git a/tests/test_tablib.py b/tests/test_tablib.py
index ca8ac05ec..1041c20ea 100755
--- a/tests/test_tablib.py
+++ b/tests/test_tablib.py
@@ -205,16 +205,19 @@ def initials(row):
         self.founders.append(('Some', 'One', 71))
         # Also acceptable when all dynamic column values are provided.
         self.founders.append(('Other', 'Second', 84, 'Other', 'OS'))
+        # Callable placeholders for dynamic columns are resolved when adding rows.
+        self.founders.append(('Brad', 'Montgomery', 70, new_col, initials))
 
         self.assertEqual(self.founders[3], ('Some', 'One', 71, 'Some', 'SO'))
         self.assertEqual(self.founders[4], ('Other', 'Second', 84, 'Other', 'OS'))
+        self.assertEqual(self.founders[5], ('Brad', 'Montgomery', 70, 'Brad', 'BM'))
         self.assertEqual(
             self.founders['first_again'],
-            ['John', 'George', 'Thomas', 'Some', 'Other']
+            ['John', 'George', 'Thomas', 'Some', 'Other', 'Brad']
         )
         self.assertEqual(
             self.founders['initials'],
-            ['JA', 'GW', 'TJ', 'SO', 'OS']
+            ['JA', 'GW', 'TJ', 'SO', 'OS', 'BM']
         )
 
         # However only partial dynamic values provided is not accepted.
@@ -226,7 +229,7 @@ def initials(row):
         self.founders.append(('After', 'Deletion', 75))
         self.assertEqual(
             self.founders['initials'],
-            ['JA', 'GW', 'TJ', 'SO', 'OS', 'AD']
+            ['JA', 'GW', 'TJ', 'SO', 'OS', 'BM', 'AD']
         )
 
     def test_header_slicing(self):