Fixed #20693 -- Add timezone support to built-in time filter.

Modified django.utils.dateformat module, moving __init__() method and
timezone-related format methods from DateFormat class to TimeFormat
base class. Modified timezone-related format methods to return an
empty string when timezone is inappropriate for input value.

1 files changed, 82 insertions, 51 deletions

diff --git a/django/utils/dateformat.py b/django/utils/dateformat.py
index 6d0a7b63f7..fbf299631b 100644
--- a/django/utils/dateformat.py
+++ b/django/utils/dateformat.py
@@ -38,8 +38,19 @@ class Formatter(object):
         return ''.join(pieces)
 
 class TimeFormat(Formatter):
-    def __init__(self, t):
-        self.data = t
+
+    def __init__(self, obj):
+        self.data = obj
+        self.timezone = None
+
+        # We only support timezone when formatting datetime objects,
+        # not date objects (timezone information not appropriate),
+        # or time objects (against established django policy).
+        if isinstance(obj, datetime.datetime):
+            if is_naive(obj):
+                self.timezone = LocalTimezone(obj)
+            else:
+                self.timezone = obj.tzinfo
 
     def a(self):
         "'a.m.' or 'p.m.'"
@@ -57,6 +68,25 @@ class TimeFormat(Formatter):
         "Swatch Internet time"
         raise NotImplementedError
 
+    def e(self):
+        """
+        Timezone name.
+
+        If timezone information is not available, this method returns
+        an empty string.
+        """
+        if not self.timezone:
+            return ""
+
+        try:
+            if hasattr(self.data, 'tzinfo') and self.data.tzinfo:
+                # Have to use tzinfo.tzname and not datetime.tzname
+                # because datatime.tzname does not expect Unicode
+                return self.data.tzinfo.tzname(self.data) or ""
+        except NotImplementedError:
+            pass
+        return ""
+
     def f(self):
         """
         Time, in 12-hour hours and minutes, with minutes left off if they're
@@ -92,6 +122,21 @@ class TimeFormat(Formatter):
         "Minutes; i.e. '00' to '59'"
         return '%02d' % self.data.minute
 
+    def O(self):
+        """
+        Difference to Greenwich time in hours; e.g. '+0200', '-0430'.
+
+        If timezone information is not available, this method returns
+        an empty string.
+        """
+        if not self.timezone:
+            return ""
+
+        seconds = self.Z()
+        sign = '-' if seconds < 0 else '+'
+        seconds = abs(seconds)
+        return "%s%02d%02d" % (sign, seconds // 3600, (seconds // 60) % 60)
+
     def P(self):
         """
         Time, in 12-hour hours, minutes and 'a.m.'/'p.m.', with minutes left off
@@ -109,24 +154,48 @@ class TimeFormat(Formatter):
         "Seconds; i.e. '00' to '59'"
         return '%02d' % self.data.second
 
+    def T(self):
+        """
+        Time zone of this machine; e.g. 'EST' or 'MDT'.
+
+        If timezone information is not available, this method returns
+        an empty string.
+        """
+        if not self.timezone:
+            return ""
+
+        name = self.timezone.tzname(self.data) if self.timezone else None
+        if name is None:
+            name = self.format('O')
+        return six.text_type(name)
+
     def u(self):
         "Microseconds; i.e. '000000' to '999999'"
         return '%06d' %self.data.microsecond
 
+    def Z(self):
+        """
+        Time zone offset in seconds (i.e. '-43200' to '43200'). The offset for
+        timezones west of UTC is always negative, and for those east of UTC is
+        always positive.
+
+        If timezone information is not available, this method returns
+        an empty string.
+        """
+        if not self.timezone:
+            return ""
+
+        offset = self.timezone.utcoffset(self.data)
+        # `offset` is a datetime.timedelta. For negative values (to the west of
+        # UTC) only days can be negative (days=-1) and seconds are always
+        # positive. e.g. UTC-1 -> timedelta(days=-1, seconds=82800, microseconds=0)
+        # Positive offsets have days=0
+        return offset.days * 86400 + offset.seconds
+
 
 class DateFormat(TimeFormat):
     year_days = [None, 0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334]
 
-    def __init__(self, dt):
-        # Accepts either a datetime or date object.
-        self.data = dt
-        self.timezone = None
-        if isinstance(dt, datetime.datetime):
-            if is_naive(dt):
-                self.timezone = LocalTimezone(dt)
-            else:
-                self.timezone = dt.tzinfo
-
     def b(self):
         "Month, textual, 3 letters, lowercase; e.g. 'jan'"
         return MONTHS_3[self.data.month]
@@ -146,17 +215,6 @@ class DateFormat(TimeFormat):
         "Day of the week, textual, 3 letters; e.g. 'Fri'"
         return WEEKDAYS_ABBR[self.data.weekday()]
 
-    def e(self):
-        "Timezone name if available"
-        try:
-            if hasattr(self.data, 'tzinfo') and self.data.tzinfo:
-                # Have to use tzinfo.tzname and not datetime.tzname
-                # because datatime.tzname does not expect Unicode
-                return self.data.tzinfo.tzname(self.data) or ""
-        except NotImplementedError:
-            pass
-        return ""
-
     def E(self):
         "Alternative month names as required by some locales. Proprietary extension."
         return MONTHS_ALT[self.data.month]
@@ -204,13 +262,6 @@ class DateFormat(TimeFormat):
         "ISO 8601 year number matching the ISO week number (W)"
         return self.data.isocalendar()[0]
 
-    def O(self):
-        "Difference to Greenwich time in hours; e.g. '+0200', '-0430'"
-        seconds = self.Z()
-        sign = '-' if seconds < 0 else '+'
-        seconds = abs(seconds)
-        return "%s%02d%02d" % (sign, seconds // 3600, (seconds // 60) % 60)
-
     def r(self):
         "RFC 2822 formatted date; e.g. 'Thu, 21 Dec 2000 16:01:07 +0200'"
         return self.format('D, j M Y H:i:s O')
@@ -232,13 +283,6 @@ class DateFormat(TimeFormat):
         "Number of days in the given month; i.e. '28' to '31'"
         return '%02d' % calendar.monthrange(self.data.year, self.data.month)[1]
 
-    def T(self):
-        "Time zone of this machine; e.g. 'EST' or 'MDT'"
-        name = self.timezone.tzname(self.data) if self.timezone else None
-        if name is None:
-            name = self.format('O')
-        return six.text_type(name)
-
     def U(self):
         "Seconds since the Unix epoch (January 1 1970 00:00:00 GMT)"
         if isinstance(self.data, datetime.datetime) and is_aware(self.data):
@@ -291,26 +335,13 @@ class DateFormat(TimeFormat):
             doy += 1
         return doy
 
-    def Z(self):
-        """
-        Time zone offset in seconds (i.e. '-43200' to '43200'). The offset for
-        timezones west of UTC is always negative, and for those east of UTC is
-        always positive.
-        """
-        if not self.timezone:
-            return 0
-        offset = self.timezone.utcoffset(self.data)
-        # `offset` is a datetime.timedelta. For negative values (to the west of
-        # UTC) only days can be negative (days=-1) and seconds are always
-        # positive. e.g. UTC-1 -> timedelta(days=-1, seconds=82800, microseconds=0)
-        # Positive offsets have days=0
-        return offset.days * 86400 + offset.seconds
 
 def format(value, format_string):
     "Convenience function"
     df = DateFormat(value)
     return df.format(format_string)
 
+
 def time_format(value, format_string):
     "Convenience function"
     tf = TimeFormat(value)