Please improve warning message "received a naive datetime while time zone support is active"

[Chris Wilson]

The warning message usually shows:

BadDataError: ('payment.Order', RuntimeWarning(u'DateTimeField received a naive datetime (2013-01-03 19:45:41.532391) while time zone support is active.',))

However it doesn't actually show which field this happened to, which makes it hard to debug without inserting breakpoints.

This three-line change to django.db.models.fields.DateTimeField:

    def get_prep_value(self, value):
        value = self.to_python(value)
        if value is not None and settings.USE_TZ and timezone.is_naive(value):
            ...
-            warnings.warn("DateTimeField received a naive datetime (%s)"
-                          " while time zone support is active." % value,
+            warnings.warn("DateTimeField %s.%s received a naive datetime (%s)"
+                          " while time zone support is active." %
+                          (self.model.__name__, self.name, value),
                          RuntimeWarning)

Which results in this output instead:

DateTimeField Order.created received a naive datetime (2013-01-03 20:11:24.084774) while time zone support is active.

[Aymeric Augustin]

The documentation explains how to turn the warnings into exceptions, providing a full backtrace.

[Chris Wilson]

Thanks aaugustin, but that's not my question, I still want to know what field was set wrongly. Because this warning/exception is only thrown at save() time, the backtrace doesn't tell you anything about the field name.

[Aymeric Augustin]

Replying to gcc:

Thanks aaugustin, but that's not my question

Sorry, I wrote that comment on a phone and it was a bit short. Let's go for a longer version now that I have a keyboard :)

1) I understood your question; I just made a tangential comment without touching the triage flags.

2) Since this isn't going to be fixed until 1.6 — we're in RC for 1.5 — developers who face the same problem and find this ticket will have to resort to another debugging method. Turning warnings into exceptions is quite powerful; I hoped my comment might help developers who aren't aware of this possibility.

3) If we make that change, the part of the documentation I'm referring to won't work any more. When you're writing a patch for this ticket, don't forget to update the docs.

[Vajrasky Kok]

Added more clarity when receiving naive datetime object when timezone support is active. Fixed the doc and test as well.

[Vajrasky Kok]

This patch (add_clarity_to_warning_receiving_naive_datetime.diff​) is based on gcc's work (credit to him/her). It also addressed aaugustin's concern regarding the documentation on turning warning to exception.

[Aymeric Augustin <aymeric.augustin@…>]

In 570d9c2678d6cc564f9c70138554af8f7ce9ec49:

Fixed #19560 -- Identified field in warning for naive datetime.

Thanks gcc for the report and vajrasky for the patch.

[Aymeric Augustin <aymeric.augustin@…>]

In ddff6522fa72aacc7475ba5cd4bf8683ff12b8c7:

[1.6.x] Fixed #19560 -- Identified field in warning for naive datetime.

Thanks gcc for the report and vajrasky for the patch.

Backport of 570d9c2678d6cc564f9c70138554af8f7ce9ec49 from master.