use default format from language or server

qweb_usertime/README.rst

@@ -9,6 +9,12 @@ the current time in the timezone of the user. It can be used as::
 
     <t t-usertime="%Y-%m-%d %H:%M:%S" />
 
+or, if you want to use the default date and time formats based on the users
+language::
+
+    <t t-usertime="" />
+
+
 Credits
 =======
 

qweb_usertime/qweb.py

@@ -27,6 +27,7 @@
 import pytz
 
 from openerp import models
+from openerp.tools import DEFAULT_SERVER_DATETIME_FORMAT
 
 _logger = logging.getLogger(__name__)
 
@@ -37,6 +38,17 @@ class QWeb(models.Model):
     def render_tag_usertime(self, element, template_attributes,
                             generated_attributes, qwebcontext):
         tformat = template_attributes['usertime']
+        if not tformat:
+            # No format, use default time and date formats from user lang
+            lang = qwebcontext['user'].lang
+            if lang:
+                lang = qwebcontext['env']['res.lang'].search(
+                    [('code', '=', lang)]
+                )
+                tformat = "{0.date_format} {0.time_format}".format(lang)
+            else:
+                tformat = DEFAULT_SERVER_DATETIME_FORMAT
+
         now = datetime.now()
 
         tz_name = qwebcontext['user'].tz