Add overwriting of default

lumen/filters/base.py

@@ -320,7 +320,7 @@ def __init__(self, **params):
         self.widget.link(self, bidirectional=True, value='value', visible='visible', disabled='disabled')
         if self._sync_with_url:
             pn.state.location.sync(self.widget, {'value': self.field}, on_error=self._url_sync_error)
-        if self.default is not None and not self.widget.value:
+        if self.default is not None and self.value is None:
             self.widget.value = self.default
 
     @classmethod

lumen/tests/test_dashboard.py

@@ -110,6 +110,18 @@ def test_dashboard_with_url_sync_filters_with_default(set_root, document):
     assert f2.value == ['foo1', 'foo2', 'foo3']
     assert f2.widget.value == ['foo1', 'foo2', 'foo3']
 
+def test_dashboard_with_url_sync_filters_with_overwritten_default(set_root, document):
+    root = pathlib.Path(__file__).parent / 'sample_dashboard'
+    set_root(str(root))
+    dashboard = Dashboard(str(root / 'sync_query_filters_default.yaml'))
+    dashboard._render_dashboard()
+    layout = dashboard.layouts[0]
+    f1, f2 = list(layout._pipelines.values())[0].filters
+    f1.value = (0.1, 0.7)
+    f2.value = []  # overwriting default with empty list
+    assert pn.state.location.search == '?A=%5B0.1%2C+0.7%5D&C=%5B%5D'
+    assert f2.widget.value == []
+
 @sql_available
 def test_dashboard_with_sql_source_and_transforms(set_root, document, mixed_df_object_type):
     root = pathlib.Path(__file__).parent / 'sample_dashboard'