Ensure Tabulator selection is updated when indexes change

panel/tests/ui/widgets/test_tabulator.py

@@ -1968,7 +1968,6 @@
         ([0, 1], 'input[type="number"]'),
         (np.array([0, 1], dtype=np.uint64), 'input[type="number"]'),
         ([0.1, 1.1], 'input[type="number"]'),
-        # ([True, False], 'input[type="checkbox"]'),  # Pandas cannot have boolean indexes apparently
     ),
 )
 def test_tabulator_header_filters_default_index(page, index, expected_selector):
@@ -3340,7 +3339,7 @@
             assert table_values == list(df2['x'].sort_values(ascending=False))
         else:
             return False
     wait_until(x_values, page)
 
 
 def test_tabulator_update_hidden_columns(page):
@@ -3506,6 +3505,8 @@
 
     page.locator('.tabulator-col-title-holder').nth(2).click()
 
+    page.wait_for_timeout(100)
+
     page.locator('.tabulator-row').nth(0).click()
 
     page.keyboard.down('Shift')
@@ -3524,6 +3525,8 @@
 
     page.locator('.tabulator-col-title-holder').nth(2).click()
 
+    page.wait_for_timeout(100)
+
     page.locator('.tabulator-row').nth(1).click()
 
     page.keyboard.down('Shift')

panel/tests/widgets/test_tables.py

@@ -240,6 +240,15 @@ def test_none_table(document, comm):
     assert model.source.data == {}
 
 
+def test_tabulator_selection_resets():
+    df = makeMixedDataFrame()
+    table = Tabulator(df, selection=list(range(len(df))))
+
+    for i in reversed(range(len(df))):
+        table.value = df.iloc[:i]
+        assert table.selection == list(range(i))
+
+
 def test_tabulator_selected_dataframe():
     df = makeMixedDataFrame()
     table = Tabulator(df, selection=[0, 2])

panel/widgets/tables.py

@@ -116,7 +116,10 @@ def __init__(self, value=None, **params):
         self._index_mapping = {}
         self._edited_indexes = []
         super().__init__(value=value, **params)
-        self.param.watch(self._setup_on_change, ['editors', 'formatters'])
+        self._internal_callbacks.extend([
+            self.param.watch(self._setup_on_change, ['editors', 'formatters']),
+            self.param._watch(self._reset_selection, ['value'], precedence=-1)
+        ])
         self.param.trigger('editors')
         self.param.trigger('formatters')
 
@@ -129,6 +132,32 @@ def _compute_renamed_cols(self):
             str(col) if str(col) != col else col: col for col in self._get_fields()
         }
 
+    def _reset_selection(self, event):
+        if event.type == 'triggered' and self._updating:
+            return
+        if self._indexes_changed(event.old, event.new):
+            selection = []
+            for sel in self.selection:
+                idx = event.old.index[sel]
+                try:
+                    new = event.new.index.get_loc(idx)
+                    selection.append(new)
+                except KeyError:
+                    pass
+            self.selection = selection
+
+    def _indexes_changed(self, old, new):
+        """
+        Comparator that checks whether DataFrame indexes have changed.
+
+        If indexes and length are unchanged we assume we do not
+        have to reset various settings including expanded rows,
+        scroll position, pagination etc.
+        """
+        if type(old) != type(new) or isinstance(new, dict) or len(old) != len(new):
+            return True
+        return (old.index != new.index).any()
+
     @property
     def _length(self):
         return len(self._processed)
@@ -1495,20 +1524,6 @@ def _get_model_children(self, panels, doc, root, parent, comm=None):
             models[i] = model
         return models
 
-    def _indexes_changed(self, old, new):
-        """
-        Comparator that checks whether DataFrame indexes have changed.
-
-        If indexes and length are unchanged we assume we do not
-        have to reset various settings including expanded rows,
-        scroll position, pagination etc.
-        """
-        if type(old) != type(new) or isinstance(new, dict):
-            return True
-        elif len(old) != len(new):
-            return False
-        return (old.index != new.index).any()
-
     def _update_children(self, *events):
         cleanup, reuse = set(), set()
         page_events = ('page', 'page_size', 'pagination')