Connect state of save/revert buttons to something sensible

stellarphot/settings/tests/test_views.py

@@ -0,0 +1,68 @@
+from stellarphot.settings import Camera, ui_generator
+from stellarphot.settings.tests.test_models import TEST_CAMERA_VALUES
+
+
+class TestUiGenerator:
+    def test_camera(self):
+        ui = ui_generator(Camera)
+        # The description should be the beginning of the docstring
+        assert Camera.__doc__.strip().startswith(ui.description.split()[0])
+
+        # We always want to show nullable fields
+        assert ui.show_null
+
+        # Which means we don't need the button to show/hide them
+        assert ui.bn_shownull.layout.display == "none"
+
+        # For now we do not show the validaation output because it is painfully
+        # verbose and not very helpful.
+        assert not ui.show_validation
+
+        # We always display nested models
+        assert ui.open_nested
+
+        # Finally, we don't want the widget to update continuously because it
+        # will overwrite the value the user entered.
+        for widget in ui.di_widgets.values():
+            if hasattr(widget, "continuous_update"):
+                assert not widget.continuous_update
+
+    def test_disabled_state_save_revert_button(self):
+        # We want the save and revert buttons to be enabled only when
+        # 1. The user has made a change, AND
+        # 2. The value in the widget is a valid pydantic model
+
+        ui = ui_generator(Camera)
+        # The save button should be disabled
+        assert ui.savebuttonbar.bn_save.disabled
+        assert ui.savebuttonbar.bn_revert.disabled
+
+        # Set one field to a valid value....
+        ui.value["name"] = "test"
+
+        # ...and the save button should still be disabled
+        assert ui.savebuttonbar.bn_save.disabled
+        assert ui.savebuttonbar.bn_revert.disabled
+
+        # Set a valid value
+        ui.value = TEST_CAMERA_VALUES
+
+        # So it turns out that the validation stuff only updates when changes are made
+        # in the UI rather than programmatically. Since we know we've set a valid value,
+        # and that we've made changes we just manually set the relevant values.
+        ui.savebuttonbar.unsaved_changes = True
+        ui.is_valid.value = True
+
+        # The save button should now be enabled
+        assert not ui.savebuttonbar.bn_save.disabled
+        assert not ui.savebuttonbar.bn_revert.disabled
+
+        # Click on save
+        ui.savebuttonbar.bn_save.click()
+
+        # Unsaved changes should be False
+        assert not ui.savebuttonbar.unsaved_changes
+
+        # The save and revert buttons should now be disabled
+        assert ui.savebuttonbar.bn_save.disabled
+        assert ui.savebuttonbar.bn_revert.disabled

stellarphot/settings/views.py

@@ -32,6 +32,9 @@ def ui_generator(model):
     # to use the entire docstring, which is often too long.
     ui.description = _extract_short_description(model.__doc__)
 
+    # Always show nested models
+    ui.open_nested = True
+
     # Validation is checked every time a value is changed, and the contents of each
     # field are written to the widget if validation passes. In at least one case,
     # the "Observatory" model, this is not helpful because the format of lat/lon is
@@ -43,4 +46,34 @@ def ui_generator(model):
         if hasattr(widget, "continuous_update"):
             widget.continuous_update = False
 
+    # The save and revert buttons should be enabled only when the user has made a
+    # change AND the value in the widget is a valid pydantic model.
+    # We begin by disabling the buttons.
+    ui.savebuttonbar.bn_save.disabled = True
+    ui.savebuttonbar.bn_revert.disabled = True
+
+    # Now we add observers to enable/disable the buttons based on the validity of
+    # the value and whether there are unsaved changes.
+    for button in [ui.savebuttonbar.bn_save, ui.savebuttonbar.bn_revert]:
+        ui.is_valid.observe(_handle_save_revert_button_state(ui, button), "value")
+        ui.savebuttonbar.observe(
+            _handle_save_revert_button_state(ui, button), "unsaved_changes"
+        )
+
     return ui
+
+
+def _handle_save_revert_button_state(widget, button):
+    """
+    Return a callback that will enable/disable the save and revert buttons based
+    on the validity of the value and whether there are unsaved changes.
+    """
+
+    def handler(_):
+        """
+        A handler must take an argument but we don't use it here.
+        """
+        needs_to_save = widget.is_valid and widget.savebuttonbar.unsaved_changes
+        button.disabled = not needs_to_save
+
+    return handler