Re: [Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |Owner:  aaugustin
 Type:  Bug|   Status:  closed
Component:  Generic views  |  Version:  master
 Severity:  Normal |   Resolution:  wontfix
 Keywords:  timezone, tz   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--
Changes (by aaugustin):

 * status:  new => closed
 * resolution:   => wontfix


Comment:

 I can now confirm that the behavior described by the reporter was
 introduced on purpose in 78ba9670af.

 Basically, this is an ill-defined problem: convert between dates and
 datetimes in a time zone aware world.

 [https://docs.djangoproject.com/en/dev/ref/class-based-views/mixins-date-
 based/#datemixin As documented here], the best solution is to back your
 date-based CBV on a `DateField` and not on a `DateTimeField`.
 Alternatively you could override `get_object`.

 

 Assuming there is a per-user timezone selection mechanism that sets the
 current time zone, and that the date-based CBV are backed on a
 `DateTimeField` -- otherwise none of these problems occur -- there are two
 possible default implementations for the date-based CBV (I say "default"
 because the point of CBVs is to let you override the bits you want):
 - use the default time zone (`settings.TIME_ZONE`)
   - the same items will always be displayed at the same URL, and the
 `DateDetailView` URLs will be permalinks
   - the date of the items, as displayed to the end user, may not match the
 URL
 - use the current time zone (the end user's time zone) -- this is what
 Django currently does
   - the same URL may display different items
   - the date of the items will always match the URL

 Both solutions are bound to annoy a subset of Django users. I've chosen
 the second one because I've heard "this page displays items for yesterday
 / tomorrow!" more often "the URL changes depending on the user!". Also,
 Django consistently works in the default time zone in the model layer and
 in the current time zone in the view / template layer. That said, to be
 honest, the CBVs span these layers, and I hesitated a lot before deciding
 to use the current time zone.

 Finally, when implementing this, I also considered forbidding date-based
 CBVs backed on `DateTimeField`s when `USE_TZ = True`. But they work
 perfectly when the current time zone isn't set per-user and stays
 identical to the default time zone, so I preferred to leave them available
 and add a warning in the docs.

 

 If you think my decisions in this area are incorrect -- which is totally
 possible as I got very little feedback during the implementation of these
 parts -- please start a discussion on the django-developers mailing-list.

 For now I will mark this "wontfix" because you're seeing a known behavior.

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Re: [Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |Owner:  aaugustin
 Type:  Bug|   Status:  new
Component:  Generic views  |  Version:  master
 Severity:  Normal |   Resolution:
 Keywords:  timezone, tz   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--
Changes (by aaugustin):

 * owner:  nobody => aaugustin
 * status:  reopened => new


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Re: [Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |Owner:  nobody
 Type:  Bug|   Status:  reopened
Component:  Generic views  |  Version:  master
 Severity:  Normal |   Resolution:
 Keywords:  timezone, tz   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--
Changes (by aaugustin):

 * status:  closed => reopened
 * resolution:  invalid =>


Comment:

 My first impression was that the OP is right, but this is an expected
 behavior.

 I'd like to double check this before closing the ticket. Thanks.

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Re: [Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |Owner:  nobody
 Type:  Bug|   Status:  closed
Component:  Generic views  |  Version:  master
 Severity:  Normal |   Resolution:  invalid
 Keywords:  timezone, tz   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--
Changes (by ashleyjsands):

 * status:  new => closed
 * resolution:   => invalid


Comment:

 I think you have misunderstood the DateMixin docstring.

 Like what Preston said, It doesn't matter what the user's timezone is, but
 rather what the system's timezone is. Different user's from around the
 world accessing the same URL should access the same resource. All URLs are
 independent from the the user's timezone.

 I have spoken to Russell M at PyCon AU about this and he agrees. You
 should open a discussion on the Django Dev mail list if you want to talk
 about it further.

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Re: [Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |Owner:  nobody
 Type:  Bug|   Status:  new
Component:  Generic views  |  Version:  master
 Severity:  Normal |   Resolution:
 Keywords:  timezone, tz   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--

Comment (by void):

 Ok, maybe I erroneosly blamed last test. But consider the attached failing
 test.

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Re: [Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |Owner:  nobody
 Type:  Bug|   Status:  new
Component:  Generic views  |  Version:  master
 Severity:  Normal |   Resolution:
 Keywords:  timezone, tz   | Triage Stage:  Unreviewed
Has patch:  0  |  Needs documentation:  0
  Needs tests:  0  |  Patch needs improvement:  0
Easy pickings:  0  |UI/UX:  0
---+--
Changes (by prestontimmons):

 * needs_docs:   => 0
 * needs_tests:   => 0
 * needs_better_patch:   => 0


Comment:

 If I'm not mistaken, the current timezone means the active `TIME_ZONE`
 setting and not the user's timezone.

 The test you mentioned saves objects with a UTC timezone, but the queries
 run are relative to the TIME_ZONE setting--set to "Africa/Nairobi"
 (UTC+3:00) in this case.

 After reviewing this, I can't see anywhere where the url would display
 different results for users worldwide.

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[Django] #18794: When timezone support is enabled, permalinks for DateDetailView are impossible.

[Django]

#18794: When timezone support is enabled, permalinks for DateDetailView are
impossible.
---+--
 Reporter:  void   |  Owner:  nobody
 Type:  Bug| Status:  new
Component:  Generic views  |Version:  master
 Severity:  Normal |   Keywords:  timezone, tz
 Triage Stage:  Unreviewed |  Has patch:  0
Easy pickings:  0  |  UI/UX:  0
---+--
 With timezone support enabled, permalinks for `DateDetailView` are hard to
 create.

 As clearly stated in docstring of `DateMixin._make_date_lookup_arg`,
 {{{
 When time zone support is enabled, `date` is assumed to be in the
 current time zone, so that displayed items are consistent with the
 URL.
 }}}

 As current time zone is a time zone of the current user, web site should
 generate different urls for different users in order them view same
 content and not 404 page. That's weird: we don't have permalinks anymore.
 User in Moscow may send a link to `DateDetailView` to another user in New
 York, and that user will see 404 page. Or it may be `DayArchiveView`, and
 user in New York will see another set of records.

 I may be not understanding something, as last test in
 `regressiontests.generic_views.dates` even checks for this 404. But what
 is the way I should generate worldwide accessible permalinks?

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Ticket URL: 
Django 
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