Fix Date translations (#2336)

* Avoid time zone conversion when translating DateTime.Date with
  timestamptz.
* Return PG date from NodaTime {Local,Zoned}DateTime.Date

Fixes #2333
Fixes #2335

(cherry picked from commit da284d6)

src/EFCore.PG.NodaTime/Query/Internal/NpgsqlNodaTimeMemberTranslatorPlugin.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 using System.Reflection;
 using Microsoft.EntityFrameworkCore;
@@ -8,6 +8,7 @@
 using Microsoft.EntityFrameworkCore.Storage;
 using NodaTime;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Query;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal;
 
 namespace Npgsql.EntityFrameworkCore.PostgreSQL.NodaTime.Query.Internal;
 
@@ -320,13 +321,11 @@ SqlExpression Upper()
                         getValueExpression
                     );
 
-            case "Date":
-                return _sqlExpressionFactory.Function(
-                    "DATE_TRUNC",
-                    new[] { _sqlExpressionFactory.Constant("day"), instance },
-                    nullable: true,
-                    argumentsPropagateNullability: TrueArrays[2],
-                    returnType);
+            // PG allows converting a timestamp directly to date, truncating the time; but given a timestamptz, it performs a time zone
+            // conversion (based on TimeZone), which we don't want (so avoid translating except on timestamp).
+            // The translation for ZonedDateTime.Date converts to timestamp before ending up here.
+            case "Date" when instance.TypeMapping is TimestampLocalDateTimeMapping:
+                return _sqlExpressionFactory.Convert(instance, typeof(LocalDate), _typeMappingSource.FindMapping(typeof(LocalDate))!);
 
             case "TimeOfDay":
                 // TODO: Technically possible simply via casting to PG time,

src/EFCore.PG/Query/ExpressionTranslators/Internal/NpgsqlDateTimeMemberTranslator.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Reflection;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
@@ -7,6 +7,7 @@
 using Microsoft.EntityFrameworkCore.Storage;
 using Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal;
 using NpgsqlTypes;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Storage.Internal.Mapping;
 using static Npgsql.EntityFrameworkCore.PostgreSQL.Utilities.Statics;
 
 namespace Npgsql.EntityFrameworkCore.PostgreSQL.Query.ExpressionTranslators.Internal;
@@ -60,6 +61,39 @@ public NpgsqlDateTimeMemberTranslator(
             return translated;
         }
 
+        if (member.Name == nameof(DateTime.Date))
+        {
+            // Note that DateTime.Date returns a DateTime, not a DateOnly (introduced later); so we convert using date_trunc (which returns
+            // a PG timestamp/timestamptz) rather than a conversion to PG date (compare with NodaTime where we want a LocalDate).
+
+            // When given a timestamptz, date_trunc performs the truncation with respect to TimeZone; to avoid that, we use the overload
+            // accepting a time zone, and pass UTC. For regular timestamp (or in legacy timestamp mode), we use the simpler overload without
+            // a time zone.
+            if (NpgsqlTypeMappingSource.LegacyTimestampBehavior || instance?.TypeMapping is NpgsqlTimestampTypeMapping)
+            {
+                return _sqlExpressionFactory.Function(
+                    "date_trunc",
+                    new[] { _sqlExpressionFactory.Constant("day"), instance! },
+                    nullable: true,
+                    argumentsPropagateNullability: TrueArrays[2],
+                    returnType,
+                    instance!.TypeMapping);
+            }
+
+            if (instance?.TypeMapping is NpgsqlTimestampTzTypeMapping)
+            {
+                return _sqlExpressionFactory.Function(
+                    "date_trunc",
+                    new[] { _sqlExpressionFactory.Constant("day"), instance, _sqlExpressionFactory.Constant("UTC") },
+                    nullable: true,
+                    argumentsPropagateNullability: TrueArrays[3],
+                    returnType,
+                    instance.TypeMapping);
+            }
+
+            return null;
+        }
+
         return member.Name switch
         {
             // Legacy behavior
@@ -95,14 +129,6 @@ public NpgsqlDateTimeMemberTranslator(
             // .NET's DayOfWeek is an enum, but its int values happen to correspond to PostgreSQL
             nameof(DateTime.DayOfWeek) => GetDatePartExpression(instance!, "dow", floor: true),
 
-            nameof(DateTime.Date) => _sqlExpressionFactory.Function(
-                "date_trunc",
-                new[] { _sqlExpressionFactory.Constant("day"), instance! },
-                nullable: true,
-                argumentsPropagateNullability: TrueArrays[2],
-                returnType,
-                instance!.TypeMapping),
-
             // TODO: Technically possible simply via casting to PG time, should be better in EF Core 3.0
             // but ExplicitCastExpression only allows casting to PG types that
             // are default-mapped from CLR types (timespan maps to interval,

test/EFCore.PG.FunctionalTests/Query/TimestampQueryTest.cs

@@ -346,6 +346,41 @@ await AssertQuery(
 
     #endregion Now
 
+    #region Date member
+
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    [MinimumPostgresVersion(12, 0)]
+    public virtual async Task Where_datetime_date_on_timestamptz(bool async)
+    {
+        await AssertQuery(
+            async,
+            ss => ss.Set<Entity>().Where(e => e.TimestamptzDateTime.Date == new DateTime(1998, 4, 12, 0, 0, 0, DateTimeKind.Utc)),
+            entryCount: 1);
+
+        AssertSql(
+            @"SELECT e.""Id"", e.""TimestampDateTime"", e.""TimestampDateTimeArray"", e.""TimestampDateTimeOffset"", e.""TimestampDateTimeOffsetArray"", e.""TimestampDateTimeRange"", e.""TimestamptzDateTime"", e.""TimestamptzDateTimeArray"", e.""TimestamptzDateTimeRange""
+FROM ""Entities"" AS e
+WHERE date_trunc('day', e.""TimestamptzDateTime"", 'UTC') = TIMESTAMPTZ '1998-04-12 00:00:00Z'");
+    }
+
+    [ConditionalTheory]
+    [MemberData(nameof(IsAsyncData))]
+    public virtual async Task Where_datetime_date_on_timestamp(bool async)
+    {
+        await AssertQuery(
+            async,
+            ss => ss.Set<Entity>().Where(e => e.TimestampDateTime.Date == new DateTime(1998, 4, 12, 0, 0, 0, DateTimeKind.Local)),
+            entryCount: 1);
+
+        AssertSql(
+            @"SELECT e.""Id"", e.""TimestampDateTime"", e.""TimestampDateTimeArray"", e.""TimestampDateTimeOffset"", e.""TimestampDateTimeOffsetArray"", e.""TimestampDateTimeRange"", e.""TimestamptzDateTime"", e.""TimestamptzDateTimeArray"", e.""TimestamptzDateTimeRange""
+FROM ""Entities"" AS e
+WHERE date_trunc('day', e.""TimestampDateTime"") = TIMESTAMP '1998-04-12 00:00:00'");
+    }
+
+    #endregion
+
     #region DateTimeOffset
 
     [ConditionalTheory]

test/EFCore.PG.NodaTime.FunctionalTests/NodaTimeQueryNpgsqlTest.cs

@@ -286,7 +286,7 @@ await AssertQuery(
         AssertSql(
             @"SELECT n.""Id"", n.""DateInterval"", n.""Duration"", n.""Instant"", n.""InstantRange"", n.""Interval"", n.""LocalDate"", n.""LocalDate2"", n.""LocalDateRange"", n.""LocalDateTime"", n.""LocalTime"", n.""Long"", n.""OffsetTime"", n.""Period"", n.""TimeZoneId"", n.""ZonedDateTime""
 FROM ""NodaTimeTypes"" AS n
-WHERE DATE_TRUNC('day', n.""LocalDateTime"") = DATE '2018-04-20'");
+WHERE n.""LocalDateTime""::date = DATE '2018-04-20'");
     }
 
     [ConditionalTheory]
@@ -1354,7 +1354,7 @@ await AssertQuery(
         AssertSql(
             @"SELECT n.""Id"", n.""DateInterval"", n.""Duration"", n.""Instant"", n.""InstantRange"", n.""Interval"", n.""LocalDate"", n.""LocalDate2"", n.""LocalDateRange"", n.""LocalDateTime"", n.""LocalTime"", n.""Long"", n.""OffsetTime"", n.""Period"", n.""TimeZoneId"", n.""ZonedDateTime""
 FROM ""NodaTimeTypes"" AS n
-WHERE DATE_TRUNC('day', n.""ZonedDateTime"" AT TIME ZONE 'UTC') = DATE '2018-04-20'");
+WHERE CAST(n.""ZonedDateTime"" AT TIME ZONE 'UTC' AS date) = DATE '2018-04-20'");
     }
 
     [ConditionalTheory]