Merge pull request #1788 from Textualize/datatable-select-headers

DataTable - Message emitted when header selected

CHANGELOG.md

@@ -35,6 +35,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 - Added `DataTable.get_row_at` to retrieve the values from a row by index https://github.com/Textualize/textual/pull/1786
 - Added `DataTable.get_column` to retrieve the values from a column by key https://github.com/Textualize/textual/pull/1786
 - Added `DataTable.get_column_at` to retrieve the values from a column by index https://github.com/Textualize/textual/pull/1786
+- Added `DataTable.HeaderSelected` which is posted when header label clicked https://github.com/Textualize/textual/pull/1788
 - Added `DOMNode.watch` and `DOMNode.is_attached` methods  https://github.com/Textualize/textual/pull/1750
 - Added `DOMNode.css_tree` which is a renderable that shows the DOM and CSS https://github.com/Textualize/textual/pull/1778
 - Added `DOMNode.children_view` which is a view on to a nodes children list, use for querying https://github.com/Textualize/textual/pull/1778

docs/widgets/data_table.md

@@ -48,6 +48,8 @@ The example below populates a table with CSV data.
 
 ### ::: textual.widgets.DataTable.ColumnSelected
 
+### ::: textual.widgets.DataTable.HeaderSelected
+
 ## Bindings
 
 The data table widget defines directly the following bindings:

src/textual/message.py

@@ -10,7 +10,6 @@ from .case import camel_to_snake
 
 if TYPE_CHECKING:
     from .message_pump import MessagePump
-    from .widget import Widget
 
 
 @rich.repr.auto

src/textual/widgets/_data_table.py

@@ -438,6 +438,29 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
             yield "cursor_column", self.cursor_column
             yield "column_key", self.column_key
 
+    class HeaderSelected(Message, bubble=True):
+        """Posted when a column header/label is clicked."""
+
+        def __init__(
+            self,
+            sender: DataTable,
+            column_key: ColumnKey,
+            column_index: int,
+            label: Text,
+        ):
+            self.column_key = column_key
+            """The key for the column."""
+            self.column_index = column_index
+            """The index for the column."""
+            self.label = label
+            """The text of the label."""
+            super().__init__(sender)
+
+        def __rich_repr__(self) -> rich.repr.Result:
+            yield "sender", self.sender
+            yield "column_key", self.column_key
+            yield "label", self.label.plain
+
     def __init__(
         self,
         *,
@@ -1327,8 +1350,7 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
         column_key = self._column_locations.get_key(column_index)
         cell_cache_key = (row_key, column_key, style, cursor, hover, self._update_count)
         if cell_cache_key not in self._cell_render_cache:
-            if not is_header_row:
+            style += Style.from_meta({"row": row_index, "column": column_index})
-                style += Style.from_meta({"row": row_index, "column": column_index})
             height = self.header_height if is_header_row else self.rows[row_key].height
             cell = self._get_row_renderables(row_index)[column_index]
             lines = self.app.console.render_lines(
@@ -1643,14 +1665,26 @@ class DataTable(ScrollView, Generic[CellType], can_focus=True):
 
     def on_click(self, event: events.Click) -> None:
         self._set_hover_cursor(True)
-        if self.show_cursor and self.cursor_type != "none":
+        meta = self.get_style_at(event.x, event.y).meta
+        if not meta:
+            return
+
+        row_index = meta["row"]
+        column_index = meta["column"]
+        is_header_click = self.show_header and row_index == -1
+        if is_header_click:
+            # Header clicks work even if cursor is off, and doesn't move the cursor.
+            column = self.ordered_columns[column_index]
+            message = DataTable.HeaderSelected(
+                self, column.key, column_index, label=column.label
+            )
+            self.post_message_no_wait(message)
+        elif self.show_cursor and self.cursor_type != "none":
             # Only post selection events if there is a visible row/col/cell cursor.
-            meta = self.get_style_at(event.x, event.y).meta
+            self.cursor_coordinate = Coordinate(row_index, column_index)
-            if meta:
+            self._post_selected_message()
-                self.cursor_coordinate = Coordinate(meta["row"], meta["column"])
+            self._scroll_cursor_into_view(animate=True)
-                self._post_selected_message()
+            event.stop()
-                self._scroll_cursor_into_view(animate=True)
-                event.stop()
 
     def action_cursor_up(self) -> None:
         self._set_hover_cursor(False)

tests/test_data_table.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import pytest
 from rich.style import Style
+from rich.text import Text
 
 from textual._wait import wait_for_idle
 from textual.actions import SkipAction
@@ -33,6 +34,7 @@ class DataTableApp(App):
         "RowSelected",
         "ColumnHighlighted",
         "ColumnSelected",
+        "HeaderSelected",
     }
 
     def __init__(self):
@@ -73,11 +75,12 @@ async def test_datatable_message_emission():
         # therefore no highlighted cells), but then a row was added, and
         # so the cell at (0, 0) became highlighted.
         expected_messages.append("CellHighlighted")
-        await pilot.pause(2 / 100)
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         # Pressing Enter when the cursor is on a cell emits a CellSelected
         await pilot.press("enter")
+        await wait_for_idle(0)
         expected_messages.append("CellSelected")
         assert app.message_names == expected_messages
 
@@ -90,11 +93,12 @@ async def test_datatable_message_emission():
         # Switch over to the row cursor... should emit a `RowHighlighted`
         table.cursor_type = "row"
         expected_messages.append("RowHighlighted")
-        await pilot.pause(2 / 100)
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         # Select the row...
         await pilot.press("enter")
+        await wait_for_idle(0)
         expected_messages.append("RowSelected")
         assert app.message_names == expected_messages
 
@@ -102,18 +106,20 @@ async def test_datatable_message_emission():
         # Switching to the column cursor emits a `ColumnHighlighted`
         table.cursor_type = "column"
         expected_messages.append("ColumnHighlighted")
-        await pilot.pause(2 / 100)
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         # Select the column...
         await pilot.press("enter")
         expected_messages.append("ColumnSelected")
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         # NONE CURSOR
         # No messages get emitted at all...
         table.cursor_type = "none"
         await pilot.press("up", "down", "left", "right", "enter")
+        await wait_for_idle(0)
         # No new messages since cursor not visible
         assert app.message_names == expected_messages
 
@@ -123,6 +129,7 @@ async def test_datatable_message_emission():
         table.show_cursor = False
         table.cursor_type = "cell"
         await pilot.press("up", "down", "left", "right", "enter")
+        await wait_for_idle(0)
         # No new messages since show_cursor = False
         assert app.message_names == expected_messages
 
@@ -130,7 +137,7 @@ async def test_datatable_message_emission():
         # message should be emitted for highlighting the cell.
         table.show_cursor = True
         expected_messages.append("CellHighlighted")
-        await pilot.pause(2 / 100)
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         # Similarly for showing the cursor again when row or column
@@ -139,14 +146,14 @@ async def test_datatable_message_emission():
         table.cursor_type = "row"
         table.show_cursor = True
         expected_messages.append("RowHighlighted")
-        await pilot.pause(2 / 100)
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         table.show_cursor = False
         table.cursor_type = "column"
         table.show_cursor = True
         expected_messages.append("ColumnHighlighted")
-        await pilot.pause(2 / 100)
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
         # Likewise, if the cursor_type is "none", and we change the
@@ -154,6 +161,7 @@ async def test_datatable_message_emission():
         # the cursor is still not visible to the user.
         table.cursor_type = "none"
         await pilot.press("up", "down", "left", "right", "enter")
+        await wait_for_idle(0)
         assert app.message_names == expected_messages
 
 
@@ -673,6 +681,40 @@ async def test_hover_coordinate():
         assert table.hover_coordinate == Coordinate(1, 2)
 
 
+async def test_header_selected():
+    """Ensure that a HeaderSelected event gets posted when we click
+    on the header in the DataTable."""
+    app = DataTableApp()
+    async with app.run_test():
+        table = app.query_one(DataTable)
+        column = table.add_column("number")
+        table.add_row(3)
+        click_event = Click(
+            sender=table,
+            x=3,
+            y=0,
+            delta_x=0,
+            delta_y=0,
+            button=0,
+            shift=False,
+            meta=False,
+            ctrl=False,
+        )
+        table.on_click(click_event)
+        await wait_for_idle(0)
+        message: DataTable.HeaderSelected = app.messages[-1]
+        assert message.sender is table
+        assert message.label == Text("number")
+        assert message.column_index == 0
+        assert message.column_key == column
+
+        # Now hide the header and click in the exact same place - no additional message emitted.
+        table.show_header = False
+        table.on_click(click_event)
+        await wait_for_idle(0)
+        assert app.message_names.count("HeaderSelected") == 1
+
+
 async def test_sort_coordinate_and_key_access():
     """Ensure that, after sorting, that coordinates and cell keys
     can still be used to retrieve the correct cell."""