1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
|
from datetime import datetime, tzinfo
from django.template import Library, Node, TemplateSyntaxError
from django.utils import six, timezone
try:
import pytz
except ImportError:
pytz = None
register = Library()
# HACK: datetime is an old-style class, create a new-style equivalent
# so we can define additional attributes.
class datetimeobject(datetime, object):
pass
# Template filters
@register.filter
def localtime(value):
"""
Converts a datetime to local time in the active time zone.
This only makes sense within a {% localtime off %} block.
"""
return do_timezone(value, timezone.get_current_timezone())
@register.filter
def utc(value):
"""
Converts a datetime to UTC.
"""
return do_timezone(value, timezone.utc)
@register.filter('timezone')
def do_timezone(value, arg):
"""
Converts a datetime to local time in a given time zone.
The argument must be an instance of a tzinfo subclass or a time zone name.
If it is a time zone name, pytz is required.
Naive datetimes are assumed to be in local time in the default time zone.
"""
if not isinstance(value, datetime):
return ''
# Obtain a timezone-aware datetime
try:
if timezone.is_naive(value):
default_timezone = timezone.get_default_timezone()
value = timezone.make_aware(value, default_timezone)
# Filters must never raise exceptions, and pytz' exceptions inherit
# Exception directly, not a specific subclass. So catch everything.
except Exception:
return ''
# Obtain a tzinfo instance
if isinstance(arg, tzinfo):
tz = arg
elif isinstance(arg, six.string_types) and pytz is not None:
try:
tz = pytz.timezone(arg)
except pytz.UnknownTimeZoneError:
return ''
else:
return ''
result = timezone.localtime(value, tz)
# HACK: the convert_to_local_time flag will prevent
# automatic conversion of the value to local time.
result = datetimeobject(result.year, result.month, result.day,
result.hour, result.minute, result.second,
result.microsecond, result.tzinfo)
result.convert_to_local_time = False
return result
# Template tags
class LocalTimeNode(Node):
"""
Template node class used by ``localtime_tag``.
"""
def __init__(self, nodelist, use_tz):
self.nodelist = nodelist
self.use_tz = use_tz
def render(self, context):
old_setting = context.use_tz
context.use_tz = self.use_tz
output = self.nodelist.render(context)
context.use_tz = old_setting
return output
class TimezoneNode(Node):
"""
Template node class used by ``timezone_tag``.
"""
def __init__(self, nodelist, tz):
self.nodelist = nodelist
self.tz = tz
def render(self, context):
with timezone.override(self.tz.resolve(context)):
output = self.nodelist.render(context)
return output
class GetCurrentTimezoneNode(Node):
"""
Template node class used by ``get_current_timezone_tag``.
"""
def __init__(self, variable):
self.variable = variable
def render(self, context):
context[self.variable] = timezone.get_current_timezone_name()
return ''
@register.tag('localtime')
def localtime_tag(parser, token):
"""
Forces or prevents conversion of datetime objects to local time,
regardless of the value of ``settings.USE_TZ``.
Sample usage::
{% localtime off %}{{ value_in_utc }}{% endlocaltime %}
"""
bits = token.split_contents()
if len(bits) == 1:
use_tz = True
elif len(bits) > 2 or bits[1] not in ('on', 'off'):
raise TemplateSyntaxError("%r argument should be 'on' or 'off'" %
bits[0])
else:
use_tz = bits[1] == 'on'
nodelist = parser.parse(('endlocaltime',))
parser.delete_first_token()
return LocalTimeNode(nodelist, use_tz)
@register.tag('timezone')
def timezone_tag(parser, token):
"""
Enables a given time zone just for this block.
The ``timezone`` argument must be an instance of a ``tzinfo`` subclass, a
time zone name, or ``None``. If is it a time zone name, pytz is required.
If it is ``None``, the default time zone is used within the block.
Sample usage::
{% timezone "Europe/Paris" %}
It is {{ now }} in Paris.
{% endtimezone %}
"""
bits = token.split_contents()
if len(bits) != 2:
raise TemplateSyntaxError("'%s' takes one argument (timezone)" %
bits[0])
tz = parser.compile_filter(bits[1])
nodelist = parser.parse(('endtimezone',))
parser.delete_first_token()
return TimezoneNode(nodelist, tz)
@register.tag("get_current_timezone")
def get_current_timezone_tag(parser, token):
"""
Stores the name of the current time zone in the context.
Usage::
{% get_current_timezone as TIME_ZONE %}
This will fetch the currently active time zone and put its name
into the ``TIME_ZONE`` context variable.
"""
# token.split_contents() isn't useful here because this tag doesn't accept variable as arguments
args = token.contents.split()
if len(args) != 3 or args[1] != 'as':
raise TemplateSyntaxError("'get_current_timezone' requires "
"'as variable' (got %r)" % args)
return GetCurrentTimezoneNode(args[2])
|