# HG changeset patch
# User Daniele Nicolodi <daniele@grinta.net>
# Date 1320401232 -3600
# Node ID f6f93996acf46f1b27890d7271365c5eae351f30
# Parent  498ed3c29a0a0a7c2eb6e4fcdd962036cdf8658f
Show timezone information for dates extracted from MySQL database.

The convenction is that all datetimes fields in the database are
stored as UTC times. Therefore we customize the mysql python connector
to convert DATETIME fields to an instance of a datetime subclass with
UTC tzinfo, and string representation showing the timezone name,
instead of the timezone naive defaul.

diff -r 498ed3c29a0a -r f6f93996acf4 src/ltpdarepo/__init__.py
--- a/src/ltpdarepo/__init__.py	Thu Nov 03 20:30:46 2011 +0100
+++ b/src/ltpdarepo/__init__.py	Fri Nov 04 11:07:12 2011 +0100
@@ -1,10 +1,13 @@
 from urlparse import urlparse, urljoin
+from datetime import datetime
 
 from flask import Flask, g, request, session, render_template, Markup, redirect, flash, url_for
 from werkzeug.exceptions import default_exceptions, InternalServerError, HTTPException
 
 from pkg_resources import get_distribution
 import MySQLdb as mysql
+import MySQLdb.converters
+import dateutil.tz
 
 from ltpdarepo.security import secure, require, authenticate
 
@@ -16,6 +19,26 @@
 secure(app)
 
 
+class datetimeutc(datetime):
+    # subclass of `datetime.datetime` with default string
+    # representation including the timezone name
+    def __str__(self):
+        return self.strftime('%Y-%m-%d %H:%M:%S %Z')
+
+
+# customize mysql types conversion for datetime fields to return
+# timezone aware objects in the UTC timezone
+def datetime_or_none_utc(s):
+    value = mysql.converters.DateTime_or_None(s)
+    if value is not None:
+        value = datetimeutc(value.year, value.month, value.day, value.hour,
+                            value.minute, value.second, value.microsecond,
+                            tzinfo=dateutil.tz.tzutc())
+    return value
+conversions = mysql.converters.conversions.copy()
+conversions[mysql.constants.FIELD_TYPE.DATETIME] = datetime_or_none_utc
+
+
 @app.before_request
 def before_request():
     # get version information from package
@@ -28,7 +51,7 @@
     # open database connection
     g.db = mysql.connect(host=app.config['HOSTNAME'], db=app.config['DATABASE'],
                          user=app.config['USERNAME'], passwd=app.config['PASSWORD'],
-                         charset='utf8')
+                         charset='utf8', conv=conversions)
 
     # validate schema revision
     curs = g.db.cursor()
diff -r 498ed3c29a0a -r f6f93996acf4 src/ltpdarepo/views/browse.py
--- a/src/ltpdarepo/views/browse.py	Thu Nov 03 20:30:46 2011 +0100
+++ b/src/ltpdarepo/views/browse.py	Fri Nov 04 11:07:12 2011 +0100
@@ -229,7 +229,7 @@
 
         value = dateutil.parser.parse(string, dayfirst=True, yearfirst=True, default=default)
         return datetime.__new__(cls, value.year, value.month, value.day, value.hour,
-                                    value.minute, value.second, value.microsecond, value.tzinfo)
+                                value.minute, value.second, value.microsecond, value.tzinfo)
 
     def __str__(self):
         return self.strftime('%Y-%m-%d %H:%M:%S %Z')