Fixed #23867 -- removed DateQuerySet hacks

The .dates() queries were implemented by using custom Query, QuerySet,
and Compiler classes. Instead implement them by using expressions and
database converters APIs.

django/db/models/expressions.py

@@ -1,11 +1,13 @@
 import copy
 import datetime
 
+from django.conf import settings
 from django.core.exceptions import FieldError
 from django.db.backends import utils as backend_utils
 from django.db.models import fields
 from django.db.models.constants import LOOKUP_SEP
 from django.db.models.query_utils import refs_aggregate
+from django.utils import timezone
 from django.utils.functional import cached_property
 
 
@@ -124,6 +126,9 @@ class ExpressionNode(CombinableMixin):
     # aggregate specific fields
     is_summary = False
 
+    def get_db_converters(self, connection):
+        return [self.convert_value]
+
     def __init__(self, output_field=None):
         self._output_field = output_field
 
@@ -531,40 +536,95 @@ class Date(ExpressionNode):
     """
     Add a date selection column.
     """
-    def __init__(self, col, lookup_type):
+    def __init__(self, lookup, lookup_type):
         super(Date, self).__init__(output_field=fields.DateField())
-        self.col = col
+        self.lookup = lookup
+        self.col = None
         self.lookup_type = lookup_type
 
     def get_source_expressions(self):
         return [self.col]
 
-    def set_source_expressions(self, exprs):
-        self.col, = self.exprs
-
-    def as_sql(self, compiler, connection):
-        sql, params = self.col.as_sql(compiler, connection)
-        assert not(params)
-        return connection.ops.date_trunc_sql(self.lookup_type, sql), []
-
-
-class DateTime(ExpressionNode):
-    """
-    Add a datetime selection column.
-    """
-    def __init__(self, col, lookup_type, tzname):
-        super(DateTime, self).__init__(output_field=fields.DateTimeField())
-        self.col = col
-        self.lookup_type = lookup_type
-        self.tzname = tzname
-
-    def get_source_expressions(self):
-        return [self.col]
-
     def set_source_expressions(self, exprs):
         self.col, = exprs
 
+    def resolve_expression(self, query, allow_joins, reuse, summarize):
+        copy = self.copy()
+        copy.col = query.resolve_ref(self.lookup, allow_joins, reuse, summarize)
+        field = copy.col.output_field
+        assert isinstance(field, fields.DateField), "%r isn't a DateField." % field.name
+        if settings.USE_TZ:
+            assert not isinstance(field, fields.DateTimeField), (
+                "%r is a DateTimeField, not a DateField." % field.name
+            )
+        return copy
+
+    def as_sql(self, compiler, connection):
+        sql, params = self.col.as_sql(compiler, connection)
+        assert not(params)
+        return connection.ops.date_trunc_sql(self.lookup_type, sql), []
+
+    def copy(self):
+        copy = super(Date, self).copy()
+        copy.lookup = self.lookup
+        copy.lookup_type = self.lookup_type
+        return copy
+
+    def convert_value(self, value, connection):
+        if isinstance(value, datetime.datetime):
+            value = value.date()
+        return value
+
+
+class DateTime(ExpressionNode):
+    """
+    Add a datetime selection column.
+    """
+    def __init__(self, lookup, lookup_type, tzinfo):
+        super(DateTime, self).__init__(output_field=fields.DateTimeField())
+        self.lookup = lookup
+        self.col = None
+        self.lookup_type = lookup_type
+        if tzinfo is None:
+            self.tzname = None
+        else:
+            self.tzname = timezone._get_timezone_name(tzinfo)
+        self.tzinfo = tzinfo
+
+    def get_source_expressions(self):
+        return [self.col]
+
+    def set_source_expressions(self, exprs):
+        self.col, = exprs
+
+    def resolve_expression(self, query, allow_joins, reuse, summarize):
+        copy = self.copy()
+        copy.col = query.resolve_ref(self.lookup, allow_joins, reuse, summarize)
+        field = copy.col.output_field
+        assert isinstance(field, fields.DateTimeField), (
+            "%r isn't a DateTimeField." % field.name
+        )
+        return copy
+
     def as_sql(self, compiler, connection):
         sql, params = self.col.as_sql(compiler, connection)
         assert not(params)
         return connection.ops.datetime_trunc_sql(self.lookup_type, sql, self.tzname)
+
+    def copy(self):
+        copy = super(DateTime, self).copy()
+        copy.lookup = self.lookup
+        copy.lookup_type = self.lookup_type
+        copy.tzname = self.tzname
+        return copy
+
+    def convert_value(self, value, connection):
+        if settings.USE_TZ:
+            if value is None:
+                raise ValueError(
+                    "Database returned an invalid value in QuerySet.datetimes(). "
+                    "Are time zone definitions for your database and pytz installed?"
+                )
+            value = value.replace(tzinfo=None)
+            value = timezone.make_aware(value, self.tzinfo)
+        return value