Implement "FIELD_change_state" methods

README.md

@@ -208,6 +208,13 @@ Returns all transitions data available in current state
 `get_available_user_FIELD_transitions`
 Enumerates all transitions data available in current state for provided user
 
+`FIELD_change_state`
+Invoke a state changing by state value.
+```python
+    post.state_change_state('publish')
+    post.state_change_state('destroy')
+```
+
 ### Foreign Key constraints support
 
 If you store the states in the db table you could use FSMKeyField to

django_fsm/__init__.py

@@ -119,6 +119,20 @@ def get_available_user_FIELD_transitions(instance, user, field):
             yield transition
 
 
+def FIELD_change_state(field):
+    """ Run transaction by next state. """
+
+    @wraps(FIELD_change_state)
+    def wrapper(instance, state, *args, **kwargs):
+        targets = dict((tt.target, tt) for tt in instance.get_available_state_transitions())
+        if state not in targets:
+            raise TransitionNotAllowed('Invalid transaction')
+        transition = targets[state]
+        field.change_state(instance, transition.method, *args, **kwargs)
+
+    return wrapper
+
+
 class FSMMeta(object):
     """
     Models methods transitions meta information
@@ -328,6 +342,7 @@ def contribute_to_class(self, cls, name, virtual_only=False):
                 curry(get_available_FIELD_transitions, field=self))
         setattr(cls, 'get_available_user_{0}_transitions'.format(self.name),
                 curry(get_available_user_FIELD_transitions, field=self))
+        setattr(cls, '{0}_change_state'.format(self.name), FIELD_change_state(self))
 
         class_prepared.connect(self._collect_transitions)
 

django_fsm/tests/test_basic_transitions.py

@@ -91,6 +91,12 @@ def test_empty_string_target(self):
         self.model.empty()
         self.assertEqual(self.model.state, '')
 
+    def test_change_state_method(self):
+        self.model.state_change_state('published')
+        self.assertEqual(self.model.state, 'published')
+        with self.assertRaises(TransitionNotAllowed):
+            self.model.state_change_state('published')
+
 
 class StateSignalsTests(TestCase):
     def setUp(self):
@@ -128,7 +134,7 @@ def test_available_conditions(self):
 
     def test_all_conditions(self):
         transitions = self.model.get_all_state_transitions()
-        
+
         actual = set((transition.source, transition.target) for transition in transitions)
         expected = set([('*', 'moderated'),
                         ('new', 'published'),