Merge branch 'main' into fix-listview-fix-remove-items

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - `TextArea.line_number_start` reactive attribute https://github.com/Textualize/textual/pull/4471
 - `Widget.remove_children` now accepts an iterable if widgets in addition to a selector https://github.com/Textualize/textual/issues/4735
+- Raise `ValueError` with improved error message when number of cells inserted using `DataTable.add_row` doesn't match the number of columns in the table https://github.com/Textualize/textual/pull/4742
 
 ### Fixed
 

src/textual/widgets/_data_table.py

@@ -1576,6 +1576,9 @@ def add_row(
         #  If we don't do this, users will be required to call add_column(s)
         #  Before they call add_row.
 
+        if len(cells) > len(self.ordered_columns):
+            raise ValueError("More values provided than there are columns.")
+
         row_index = self.row_count
         # Map the key of this row to its current index
         self._row_locations[row_key] = row_index

tests/test_data_table.py

@@ -254,6 +254,14 @@ async def test_add_row_duplicate_key():
         with pytest.raises(DuplicateKey):
             table.add_row("2", key="1")  # Duplicate row key
 
+async def test_add_row_too_many_values():
+    app = DataTableApp()
+    async with app.run_test():
+        table = app.query_one(DataTable)
+        table.add_column("A")
+        table.add_row("1", key="1")
+        with pytest.raises(ValueError):
+            table.add_row("1", "2")
 
 async def test_add_column_duplicate_key():
     app = DataTableApp()