Add on_change_callback to config variables. These callback can be defined in the ConfigVariable object and is called, when the variable is changed.

openslides/config/api.py

@@ -31,9 +31,12 @@ class ConfigHandler(object):
             return self[key]
 
     def __setitem__(self, key, value):
+        # Save the new value to the database
         updated_rows = ConfigStore.objects.filter(key=key).update(value=value)
         if not updated_rows:
             ConfigStore.objects.create(key=key, value=value)
+
+        # Update cache
         try:
             self._cache[key] = value
         except AttributeError:
@@ -41,6 +44,13 @@ class ConfigHandler(object):
             # called. In this case nothing should happen.
             pass
 
+        # Call on_change callback
+        for receiver, config_page in config_signal.send(sender=self):
+            for config_variable in config_page.variables:
+                if config_variable.name == key and config_variable.on_change:
+                    config_variable.on_change()
+                    break
+
     def setup_cache(self):
         """
         Loads all config variables from the database and by sending a
@@ -144,9 +154,11 @@ class ConfigVariable(object):
     A simple object class to wrap new config variables. The keyword
     arguments 'name' and 'default_value' are required. The keyword
     argument 'form_field' has to be set, if the variable should appear
-    on the ConfigView.
+    on the ConfigView. The argument 'on_change' can get a callback
+    which is called every time, the variable is changed.
     """
-    def __init__(self, name, default_value, form_field=None):
+    def __init__(self, name, default_value, form_field=None, on_change=None):
         self.name = name
         self.default_value = default_value
         self.form_field = form_field
+        self.on_change = on_change

tests/config/test_config.py

@@ -26,6 +26,9 @@ class HandleConfigTest(TestCase):
     def get_config_var(self, key):
         return config[key]
 
+    def set_config_var(self, key, value):
+        config[key] = value
+
     def test_get_config_default_value(self):
         self.assertEqual(config['string_var'], 'default_string_rien4ooCZieng6ah')
         self.assertTrue(config['bool_var'])
@@ -73,6 +76,19 @@ class HandleConfigTest(TestCase):
         """
         config['my_config_var'] = 'value'
 
+    def test_on_change(self):
+        """
+        Tests that the special callback is called and raises a special
+        message.
+        """
+        self.assertRaisesMessage(
+            Exception,
+            'Change callback dhcnfg34dlg06kdg successfully called.',
+            self.set_config_var,
+            key='var_with_callback_ghvnfjd5768gdfkwg0hm2',
+            value='new_string_kbmbnfhdgibkdjshg452bc')
+        self.assertEqual(config['var_with_callback_ghvnfjd5768gdfkwg0hm2'], 'new_string_kbmbnfhdgibkdjshg452bc')
+
 
 class ConfigFormTest(TestCase):
 
@@ -286,3 +302,16 @@ def set_simple_config_page_disabled_page(sender, **kwargs):
                       url='testsimplepage3',
                       required_permission='No permission required',
                       variables=(ConfigVariable(name='hidden_config_var_2', default_value=''),))
+
+
+@receiver(config_signal, dispatch_uid='set_simple_config_page_with_callback_for_testing')
+def set_simple_config_page_with_callback(sender, **kwargs):
+    def callback():
+        raise Exception('Change callback dhcnfg34dlg06kdg successfully called.')
+    return ConfigPage(title='Hvndfhsbgkridfgdfg',
+                      url='testsimplepage4',
+                      required_permission='No permission required',
+                      variables=(ConfigVariable(
+                          name='var_with_callback_ghvnfjd5768gdfkwg0hm2',
+                          default_value='',
+                          on_change=callback),))