Datatable remove row (#2253)

* Checking in remove_row progress

* Ensuring structures updated correctly when row deleted

* Clamping index

* Failed attempt

* Removing rows

* Update a type hint in DataTable

* Remove some code that wasnt required

* Use index syntax instead of get

* Add DataTable remove row test

* Snapshot tests for removing rows

* Add a docstring for DataTable.remove_row method

* Update changelog regarding DataTable.remove_row

* Add check_idle call to remove_row

CHANGELOG.md

@@ -5,11 +5,11 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
-
 ## Unreleased
 
 ### Added
 
+- Added `DataTable.remove_row` method https://github.com/Textualize/textual/pull/2253
 - `Widget.scroll_to_center` now scrolls the widget to the center of the screen https://github.com/Textualize/textual/pull/2255
 
 ## [0.19.1] - 2023-04-10

src/textual/_two_way_dict.py

@@ -29,6 +29,9 @@ def __delitem__(self, key: Key) -> None:
         self._forward.__delitem__(key)
         self._reverse.__delitem__(value)
 
+    def __iter__(self):
+        return iter(self._forward)
+
     def get(self, key: Key) -> Value:
         """Given a key, efficiently lookup and return the associated value.
 

src/textual/widgets/_data_table.py

@@ -308,7 +308,9 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
     cursor_coordinate: Reactive[Coordinate] = Reactive(
         Coordinate(0, 0), repaint=False, always_update=True
     )
-    hover_coordinate: Reactive[Coordinate] = Reactive(Coordinate(0, 0), repaint=False)
+    hover_coordinate: Reactive[Coordinate] = Reactive(
+        Coordinate(0, 0), repaint=False, always_update=True
+    )
 
     class CellHighlighted(Message, bubble=True):
         """Posted when the cursor moves to highlight a new cell.
@@ -1186,6 +1188,10 @@ def clear(self, columns: bool = False) -> Self:
         self._label_column = Column(self._label_column_key, Text(), auto_width=True)
         self._labelled_row_exists = False
         self.refresh()
+        self.scroll_x = 0
+        self.scroll_y = 0
+        self.scroll_target_x = 0
+        self.scroll_target_y = 0
         return self
 
     def add_column(
@@ -1322,6 +1328,41 @@ def add_rows(self, rows: Iterable[Iterable[CellType]]) -> list[RowKey]:
             row_keys.append(row_key)
         return row_keys
 
+    def remove_row(self, row_key: RowKey | str) -> None:
+        """Remove a row (identified by a key) from the DataTable.
+
+        Args:
+            row_key: The key identifying the row to remove.
+
+        Raises:
+            RowDoesNotExist: If the row key does not exist.
+        """
+        if row_key not in self._row_locations:
+            raise RowDoesNotExist(f"Row key {row_key!r} is not valid.")
+
+        self._require_update_dimensions = True
+        self.check_idle()
+
+        index_to_delete = self._row_locations.get(row_key)
+        new_row_locations = TwoWayDict({})
+        for row_location_key in self._row_locations:
+            row_index = self._row_locations.get(row_location_key)
+            if row_index > index_to_delete:
+                new_row_locations[row_location_key] = row_index - 1
+            elif row_index < index_to_delete:
+                new_row_locations[row_location_key] = row_index
+
+        self._row_locations = new_row_locations
+
+        del self.rows[row_key]
+        del self._data[row_key]
+
+        self.cursor_coordinate = self.cursor_coordinate
+        self.hover_coordinate = self.hover_coordinate
+
+        self._update_count += 1
+        self.refresh(layout=True)
+
     def on_idle(self) -> None:
         """Runs when the message pump is empty.
 

tests/snapshot_tests/snapshot_apps/data_table_remove_row.py

@@ -0,0 +1,51 @@
+from textual.app import App, ComposeResult
+from textual.binding import Binding
+from textual.widgets import DataTable
+
+ROWS = [
+    ("lane", "swimmer", "country", "time"),
+    (5, "Chad le Clos", "South Africa", 51.14),
+    (4, "Joseph Schooling", "Singapore", 50.39),
+    (2, "Michael Phelps", "United States", 51.14),
+    (6, "László Cseh", "Hungary", 51.14),
+    (3, "Li Zhuhao", "China", 51.26),
+    (8, "Mehdy Metella", "France", 51.58),
+    (7, "Tom Shields", "United States", 51.73),
+    (10, "Darren Burns", "Scotland", 51.84),
+    (1, "Aleksandr Sadovnikov", "Russia", 51.84),
+]
+
+
+class TableApp(App):
+    """Snapshot app for testing removal of rows.
+    Removes several rows, so we can check that the display of the
+    DataTable updates as expected."""
+
+    BINDINGS = [
+        Binding("r", "remove_row", "Remove Row"),
+    ]
+
+    def compose(self) -> ComposeResult:
+        yield DataTable()
+
+    def on_mount(self) -> None:
+        table = self.query_one(DataTable)
+        table.focus()
+        rows = iter(ROWS)
+        column_labels = next(rows)
+        for column in column_labels:
+            table.add_column(column, key=column)
+
+        for row in rows:
+            table.add_row(*row, key=str(row[0]))
+
+    def action_remove_row(self):
+        table = self.query_one(DataTable)
+        table.remove_row("2")
+        table.remove_row("8")
+        table.remove_row("1")
+
+
+app = TableApp()
+if __name__ == "__main__":
+    app.run()

tests/snapshot_tests/test_snapshots.py

@@ -116,6 +116,11 @@ def test_datatable_sort_multikey(snap_compare):
     assert snap_compare(SNAPSHOT_APPS_DIR / "data_table_sort.py", press=press)
 
 
+def test_datatable_remove_row(snap_compare):
+    press = ["r"]
+    assert snap_compare(SNAPSHOT_APPS_DIR / "data_table_remove_row.py", press=press)
+
+
 def test_datatable_labels_and_fixed_data(snap_compare):
     # Ensure that we render correctly when there are fixed rows/cols and labels.
     assert snap_compare(SNAPSHOT_APPS_DIR / "data_table_row_labels.py")

tests/test_data_table.py

@@ -289,6 +289,19 @@ async def test_add_columns_user_defined_keys():
         assert key == key
 
 
+async def test_remove_row():
+    app = DataTableApp()
+    async with app.run_test():
+        table = app.query_one(DataTable)
+        table.add_columns("A", "B")
+        for row in ROWS:
+            table.add_row(row, key=row[0])
+
+        assert len(table.rows) == 3
+        table.remove_row(ROWS[0][0])
+        assert len(table.rows) == 2
+
+
 async def test_clear():
     app = DataTableApp()
     async with app.run_test():