Allow to update the completions options from a parameter

panel/param.py

@@ -485,7 +485,11 @@ def link(change, watchers=[watcher]):
                     self._rerender()
                 return
             elif change.what == 'objects':
-                updates['options'] = p_obj.get_range()
+                options = p_obj.get_range()
+                if ('options' in widget.param and
+                    isinstance(widget.param['options'], param.List)):
+                    options = list(options)
+                updates['options'] = options
             elif change.what == 'bounds':
                 start, end = p_obj.get_soft_bounds()
                 supports_bounds = hasattr(widget, 'start')

panel/tests/test_param.py

@@ -5,7 +5,9 @@
 from bokeh.models import (
     Div, Slider, Select, RangeSlider as BkRangeSlider, MultiSelect,
     Row as BkRow, CheckboxGroup, Toggle, Button, TextInput as
-    BkTextInput,Tabs as BkTabs, Column as BkColumn, TextInput)
+    BkTextInput,Tabs as BkTabs, Column as BkColumn, TextInput,
+    AutocompleteInput as BkAutocompleteInput,
+)
 from panel.pane import Pane, PaneBase, Matplotlib, Bokeh, HTML
 from panel.layout import Tabs, Row
 from panel.param import Param, ParamMethod, ParamFunction, JSONInit
@@ -1235,15 +1237,29 @@ class Test(param.Parameterized):
     assert numinput.start == 0
     assert numinput.end == 5
 
-def test_set_widget_autocompleteinput():
+def test_set_widget_autocompleteinput(document, comm):
 
     class Test(param.Parameterized):
-        choice = param.Selector(objects=['a', 'b'])
+        # Testing with default='' and check_on_set=False since this feels
+        # like the most sensible default config for Selector -> AutocompleteInput
+        choice = param.Selector(default='', objects=['a', 'b'], check_on_set=False)
 
     test = Test()
-    p = Param(test, widgets={'choice': AutocompleteInput})
+    test_pane = Param(test, widgets={'choice': AutocompleteInput})
 
-    autocompleteinput = p.layout[1]
+    model = test_pane.get_root(document, comm=comm)
+
+    autocompleteinput = model.children[1]
+    assert isinstance(autocompleteinput, BkAutocompleteInput)
+    assert autocompleteinput.completions == ['a', 'b']
+    assert autocompleteinput.value == ''
+    assert autocompleteinput.disabled == False
 
-    assert autocompleteinput.value == 'a'
-    assert autocompleteinput.options == ['a', 'b']
+    # Check changing param value updates widget
+    test.choice = 'b'
+    assert autocompleteinput.value == 'b'
+
+    # Check changing param attribute updates widget
+    test.param['choice'].objects = ['c', 'd']
+    assert autocompleteinput.completions == ['c', 'd']
+    assert autocompleteinput.value == ''

panel/widgets/select.py

@@ -242,6 +242,13 @@ class AutocompleteInput(Widget):
 
     _rename = _AutocompleteInput_rename
 
+    def _process_param_change(self, msg):
+        msg = super()._process_param_change(msg)
+        if 'completions' in msg:
+            if self.restrict and not isIn(self.value, msg['completions']):
+                msg['value'] = self.value = ''
+        return msg
+
 
 class _RadioGroupBase(SingleSelectBase):