Fix and test changing file format for existing components

We need to rescan files in case we change loader and also the file
format cache needs to be reset in this case.

Fixes #647
Signed-off-by: Michal Čihař <michal@cihar.com>

weblate/trans/models/subproject.py

@@ -1143,6 +1143,7 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
         '''
         # Detect if VCS config has changed (so that we have to pull the repo)
         changed_git = True
+        changed_setup = False
         if self.id:
             old = SubProject.objects.get(pk=self.id)
             changed_git = (
@@ -1150,6 +1151,10 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
                 or (old.branch != self.branch)
                 or (old.filemask != self.filemask)
             )
+            changed_setup = (
+                (old.file_format != self.file_format)
+                or (old.template != self.template)
+            )
             # Detect slug changes and rename git repo
             self.check_rename(old)
 
@@ -1170,7 +1175,9 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
 
         # Rescan for possibly new translations if there were changes, needs to
         # be done after actual creating the object above
-        if changed_git:
+        if changed_setup:
+            self.create_translations(force=True)
+        elif changed_git:
             self.create_translations()
 
     def _get_percents(self):
@@ -1208,7 +1215,8 @@ class SubProject(models.Model, PercentMixin, URLMixin, PathMixin):
         '''
         Returns file format object.
         '''
-        if self._file_format is None:
+        if (self._file_format is None
+                or self._file_format.name != self.file_format):
             self._file_format = FILE_FORMATS[self.file_format]
         return self._file_format
 

weblate/trans/tests/test_models.py

@@ -662,6 +662,18 @@ class SubProjectTest(RepoTestCase):
         # With correct format it should validate
         subproject.full_clean()
 
+    def test_change_to_mono(self):
+        """Test swtiching to monolingual format on the fly."""
+        component = self._create_subproject(
+            'po',
+            'po-mono/*.po',
+        )
+        self.assertEqual(component.translation_set.count(), 4)
+        component.file_format = 'po-mono'
+        component.template = 'po-mono/en.po'
+        component.save()
+        self.assertEqual(component.translation_set.count(), 3)
+
 
 class TranslationTest(RepoTestCase):
     """