templates: fix encoding handling in django templates (#20831)

tests/test_templates.py

@@ -66,6 +66,11 @@ def test_template_encoding():
     assert tmpl.render({'foo': 'fou'}) == 'fou à vélo'
     assert tmpl.render({'foo': 'félé'}) == 'félé à vélo'
 
+    tmpl = Template("{% if foo == 'félé' %}à vélo{% endif %}")
+    assert tmpl.render() == ''
+    assert tmpl.render({'foo': 'fou'}) == ''
+    assert tmpl.render({'foo': 'félé'}) == 'à vélo'
+
     # ezt
     tmpl = Template('[foo] à vélo')
     assert tmpl.render() == '[foo] à vélo'

wcs/qommon/template.py

@@ -449,6 +449,14 @@ def ezt_raises(exception, on_parse=False):
     raise TemplateError(message % ' '.join(parts))
 
 
+class UnicodeDjangoContext(DjangoContext):
+    def __getitem__(self, key):
+        s = super(UnicodeDjangoContext, self).__getitem__(key)
+        if isinstance(s, str):
+            return unicode(s, 'utf-8')
+        return s
+
+
 class Template(object):
     def __init__(self, value, raises=False, ezt_format=ezt.FORMAT_RAW, ezt_only=False):
         '''Guess kind of template (Django or ezt), and parse it'''
@@ -482,7 +490,7 @@ class Template(object):
         return str(self.value)
 
     def django_render(self, context={}):
-        context = DjangoContext(context)
+        context = UnicodeDjangoContext(context)
         try:
             rendered = self.template.render(context)
         except (DjangoTemplateSyntaxError, DjangoVariableDoesNotExist) as e: