Localizer: add a context manager to temporarily change language

product/ERP5Type/tests/testLocalizer.py

@@ -127,6 +127,64 @@ class TestLocalizer(ERP5TypeTestCase):
       self.portal.portal_activities.process_timer(None, None)
     self.assertEquals(tmp_obj.getComment(), "C'est 1€.")
 
+  def test_get_selected_language(self):
+    # default selected language is en
+    self.assertEquals('en', self.portal.Localizer.get_selected_language())
+
+  def test_translationContext(self):
+    self.message_catalog._messages['This is 1€.'] = PersistentMapping(
+      {'fr':"C'est 1€.", 'note':'',})
+    localizer = self.portal.Localizer
+    with localizer.translationContext('fr'):
+      self.assertEquals('fr', localizer.get_selected_language())
+      self.assertEquals("C'est 1€.",
+        self.portal.Base_translateString("This is 1€."))
+    # outside of this context manager we are back to english
+    self.assertEquals('en', localizer.get_selected_language())
+    self.assertEquals("This is 1€.",
+      self.portal.Base_translateString("This is 1€."))
+
+  def test_translationContextActivity(self):
+    portal = self.portal
+    self.message_catalog._messages['This is 1€.'] = PersistentMapping(
+      {'fr':"C'est 1€.", 'note':'',})
+    localizer = portal.Localizer
+
+    test_script = createZODBPythonScript(portal.portal_skins.custom,
+        'test_script', '', """
+def assertEquals(a, b):
+  if a != b:
+    raise AssertionError("%r != %r" % (a, b))
+localizer = context.getPortalObject().Localizer
+with localizer.translationContext('fr'):
+  assertEquals('fr', localizer.get_selected_language())
+  assertEquals("C'est 1€.", context.Base_translateString("This is 1€."))
+# outside of this context manager we are back to english
+assertEquals('en', localizer.get_selected_language())
+assertEquals("This is 1€.", context.Base_translateString("This is 1€."))
+""")
+
+    # normal activity
+    portal.portal_activities.activate().test_script()
+    self.tic()
+    # after activity execution we are still in english
+    self.assertEquals('en', localizer.get_selected_language())
+    self.assertEquals("This is 1€.",
+      self.portal.Base_translateString("This is 1€."))
+
+    # execute activity with group_method
+    portal.portal_activities.activate(group_method_id=None).test_script()
+    self.tic()
+    # after activity execution we are still in english
+    self.assertEquals('en', localizer.get_selected_language())
+    self.assertEquals("This is 1€.",
+      self.portal.Base_translateString("This is 1€."))
+
+  def test_get_request(self):
+    # check that Localizer's get_request hack works as expected
+    from Products.Localizer.utils import get_request
+    self.assertEquals(get_request(), self.portal.REQUEST)
+
 def test_suite():
   suite = unittest.TestSuite()
   suite.addTest(unittest.makeSuite(TestLocalizer))

product/Localizer/Localizer.py

@@ -16,6 +16,7 @@
 
 # Import from the Standard Library
 from urllib import unquote
+from contextlib import contextmanager
 
 # Import from Zope
 from AccessControl import ClassSecurityInfo
@@ -216,7 +217,10 @@ class Localizer(LanguageManager, Folder):
     security.declarePublic('changeLanguage')
     changeLanguageForm = LocalDTMLFile('ui/changeLanguageForm', globals())
     def changeLanguage(self, lang, goto=None, expires=None):
-        """ """
+        """Change the user language to `lang`.
+
+        This method will set a cookie and redirect to `goto` URL.
+        """
         request = self.REQUEST
         response = request.RESPONSE
 
@@ -234,6 +238,35 @@ class Localizer(LanguageManager, Folder):
 
         response.redirect(goto)
 
+    security.declarePublic('translationContext')
+    @contextmanager
+    def translationContext(self, lang):
+      """Context manager to temporarily change the current language.
+      """
+      class ForcedLanguage:
+        __allow_access_to_unprotected_subobjects__ = 1
+        def __init__(self, lang):
+          self.lang = lang
+        def select_language(self, available_languages):
+          return self.lang
+        def set(self, lang, priority):
+          if lang != self.lang:
+            LOG('Localizer', PROBLEM,
+               'Cannot change language inside a translationContext', error=1)
+      MARKER = []
+      from patches import get_request # late import, as this is patched by
+                                      # unit tests
+      request = get_request() # Localizer always use this request internally
+      old_accept_language = request.get('AcceptLanguage', MARKER)
+      request.set('AcceptLanguage', ForcedLanguage(lang))
+      try:
+        assert self.get_selected_language() == lang
+        yield
+      finally:
+        request.other.pop('AcceptLanguage')
+        if old_accept_language is not MARKER:
+          request.set('AcceptLanguage', old_accept_language)
+
     security.declarePublic('translate')
     def translate(self, domain, msgid, lang=None, *args, **kw):
         """