Add value_label parameter to Select-like widgets

panel/widgets/select.py

@@ -32,7 +32,7 @@
     RadioButtonGroup as _BkRadioButtonGroup, SingleSelect as _BkSingleSelect,
 )
 from ..util import (
-    PARAM_NAME_PATTERN, indexOf, isIn, unique_iterator,
+    PARAM_NAME_PATTERN, edit_readonly, indexOf, isIn, unique_iterator,
 )
 from ._mixin import TooltipMixin
 from .base import CompositeWidget, Widget
@@ -79,12 +79,22 @@ class SingleSelectBase(SelectBase):
 
     value = param.Parameter(default=None)
 
+    value_label = param.String(allow_None=True, constant=True)
+
     _allows_values: ClassVar[bool] = True
 
     _allows_none: ClassVar[bool] = False
 
     _supports_embed: bool = True
 
+    _rename: ClassVar[Mapping[str, str | None]] = {
+        'value_label': None,
+    }
+
+    _source_transforms: ClassVar[Mapping[str, str | None]] = {
+        'value_label': None
+    }
+
     __abstract = True
 
     def __init__(self, **params):
@@ -93,6 +103,16 @@ def __init__(self, **params):
         if self.value is None and None not in values and values and not self._allows_none:
             self.value = values[0]
 
+    @param.depends('value', watch=True, on_init=True)
+    def _update_value_label(self):
+        try:
+            idx = indexOf(self.value, self.values)
+            label = self.labels[idx]
+        except ValueError:
+            label = None
+        with edit_readonly(self):
+            self.value_label = label
+
     def _process_param_change(self, msg):
         msg = super()._process_param_change(msg)
         labels, values = self.labels, self.values
@@ -204,7 +224,7 @@ class Select(SingleSelectBase):
     }
 
     _source_transforms: ClassVar[Mapping[str, str | None]] = {
-        'size': None, 'groups': None
+        'size': None, 'groups': None, 'value_label': None
     }
 
     _stylesheets: ClassVar[list[str]] = [f'{CDN_DIST}css/select.css']
@@ -1012,7 +1032,7 @@ class _RadioGroupBase(SingleSelectBase):
         'name': None, 'options': 'labels', 'value': 'active'
     }
 
-    _source_transforms = {'value': "source.labels[value]"}
+    _source_transforms = {'value': "source.labels[value]", 'value_label': None}
 
     _target_transforms = {'value': "target.labels.indexOf(value)"}
 
@@ -1084,7 +1104,7 @@ class RadioButtonGroup(_RadioGroupBase, _ButtonBase, TooltipMixin):
     _rename: ClassVar[Mapping[str, str | None]] = {**_RadioGroupBase._rename, **TooltipMixin._rename}
 
     _source_transforms = {
-        'value': "source.labels[value]", 'button_style': None, 'description': None
+        'value': "source.labels[value]", 'button_style': None, 'description': None, 'value_label': None
     }
 
     _supports_embed: bool = True
@@ -1127,7 +1147,7 @@ class _CheckGroupBase(SingleSelectBase):
 
     _rename: ClassVar[Mapping[str, str | None]] = {'name': None, 'options': 'labels', 'value': 'active'}
 
-    _source_transforms = {'value': "value.map((index) => source.labels[index])"}
+    _source_transforms = {'value': "value.map((index) => source.labels[index])", 'value_label': None}
 
     _target_transforms = {'value': "value.map((label) => target.labels.indexOf(label))"}
 
@@ -1186,7 +1206,7 @@ class CheckButtonGroup(_CheckGroupBase, _ButtonBase, TooltipMixin):
 
     _source_transforms = {
         'value': "value.map((index) => source.labels[index])", 'button_style': None,
-        'description': None
+        'description': None, 'value_label': None
     }
 
     _widget_type: ClassVar[type[Model]] = _BkCheckboxButtonGroup