Shelter stable dates from USE_TZ

Some dates (publication dates, author dates) are meant as _literals_. What
the user inputs through a `SelectDateWidget` should be preserved as-is.
Django's otherwise-excelent support for timezones interferes with it (see

Until a better fate of these columns is determined (do we migrate them to a
DateField?), and as a stop-gap measure, we can start being faithful to the
data by storing them in the Eastern-most timezone.

This is particularly important because 1/1/YYYY is a common pattern in
publication dates, given bookwyrm-social#743.

bookwyrm/models/author.py

@@ -32,8 +32,8 @@ class Author(BookDataModel):
         max_length=255, blank=True, null=True, deduplication_field=True
     )
     # idk probably other keys would be useful here?
-    born = fields.DateTimeField(blank=True, null=True)
-    died = fields.DateTimeField(blank=True, null=True)
+    born = fields.StableDateField(blank=True, null=True)
+    died = fields.StableDateField(blank=True, null=True)
     name = fields.CharField(max_length=255)
     aliases = fields.ArrayField(
         models.CharField(max_length=255), blank=True, default=list

bookwyrm/models/book.py

@@ -135,8 +135,8 @@ class Book(BookDataModel):
     preview_image = models.ImageField(
         upload_to="previews/covers/", blank=True, null=True
     )
-    first_published_date = fields.DateTimeField(blank=True, null=True)
-    published_date = fields.DateTimeField(blank=True, null=True)
+    first_published_date = fields.StableDateField(blank=True, null=True)
+    published_date = fields.StableDateField(blank=True, null=True)
 
     objects = InheritanceManager()
     field_tracker = FieldTracker(fields=["authors", "title", "subtitle", "cover"])

bookwyrm/models/fields.py

@@ -1,6 +1,6 @@
 """ activitypub-aware django model fields """
 from dataclasses import MISSING
-from datetime import datetime
+from datetime import date, datetime, timedelta
 import re
 from uuid import uuid4
 from urllib.parse import urljoin
@@ -11,7 +11,11 @@
 from django.contrib.postgres.fields import CICharField as DjangoCICharField
 from django.core.exceptions import ValidationError
 from django.db import models
-from django.forms import ClearableFileInput, ImageField as DjangoImageField
+from django.forms import (
+    ClearableFileInput,
+    DateField as DjangoDateField,
+    ImageField as DjangoImageField,
+)
 from django.utils import timezone
 from django.utils.translation import gettext_lazy as _
 from django.utils.encoding import filepath_to_uri
@@ -537,7 +541,6 @@ def field_to_activity(self, value):
     def field_from_activity(self, value, allow_external_connections=True):
         missing_fields = datetime(1970, 1, 1)  # "2022-10" => "2022-10-01"
         try:
-            # TODO(dato): investigate `ignoretz=True` wrt bookwyrm#3028.
             date_value = dateutil.parser.parse(value, default=missing_fields)
             try:
                 return timezone.make_aware(date_value)
@@ -547,6 +550,37 @@ def field_from_activity(self, value, allow_external_connections=True):
             return None
 
 
+class StableDateFormField(DjangoDateField):  # should be in forms/fields.py
+    """converts datetime to date, purposedly ignoring USE_TZ"""
+
+    def prepare_value(self, value):
+        if isinstance(value, datetime):
+            return value.date()
+        return value
+
+
+class StableDateField(DateTimeField):
+    """a date in a datetime column, forcibly unaffected by USE_TZ"""
+
+    # TODO: extend to PartialStableDate (or SealedDate).
+
+    def formfield(self, **kwargs):
+        kwargs.setdefault("form_class", StableDateFormField)
+        return super().formfield(**kwargs)
+
+    def to_python(self, value):
+        if isinstance(value, date):
+            tz = timezone.get_fixed_timezone(timedelta(hours=-12))
+            naive_dt = datetime(value.year, value.month, value.day)
+            # Convert to midnight in a timezone that has a stable date
+            # across the globe. (This is a hotfix while we keep on
+            # storing stable dates as DateTimeField.)
+            return timezone.make_aware(naive_dt, tz)
+        return super().to_python(value)  # XXX Just return value?
+
+    # TODO: override field_from_activity(), if necessary?
+
+
 class HtmlField(ActivitypubFieldMixin, models.TextField):
     """a text field for storing html"""
 

bookwyrm/tests/views/books/test_edit_book.py

@@ -211,7 +211,6 @@ def test_create_book(self):
         book = models.Edition.objects.get(title="New Title")
         self.assertEqual(book.parent_work.title, "New Title")
 
-    @expectedFailure  # bookwyrm#3028
     def test_create_book_published_date(self):
         """create a book and verify its publication date"""
         view = views.ConfirmEditBook.as_view()