[BACKPORT] Add support for CONVERT_TZ via EF.Functions.ConvertTimeZone()

src/EFCore.MySql/Extensions/MySqlDbFunctionsExtensions.cs

@@ -14,6 +14,158 @@ namespace Microsoft.EntityFrameworkCore
     /// </summary>
     public static class MySqlDbFunctionsExtensions
     {
+        #region ConvertTimeZone
+
+        /// <summary>
+        ///     Converts the `DateTime` value <paramref name="dateTime"/> from the time zone given by <paramref name="fromTimeZone"/> to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, fromTimeZone, toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateTime">The `DateTime` value to convert.</param>
+        /// <param name="fromTimeZone">The time zone to convert from.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateTime? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateTime dateTime,
+            string fromTimeZone,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateOnly` value <paramref name="dateOnly"/> from the time zone given by <paramref name="fromTimeZone"/> to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, fromTimeZone, toTimeZone)`..
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateOnly">The `DateOnly` value to convert.</param>
+        /// <param name="fromTimeZone">The time zone to convert from.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateOnly? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateOnly dateOnly,
+            string fromTimeZone,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateTime?` value <paramref name="dateTime"/> from the time zone given by <paramref name="fromTimeZone"/> to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, fromTimeZone, toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateTime">The `DateTime?` value to convert.</param>
+        /// <param name="fromTimeZone">The time zone to convert from.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateTime? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateTime? dateTime,
+            string fromTimeZone,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateOnly?` value <paramref name="dateOnly"/> from the time zone given by <paramref name="fromTimeZone"/> to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, fromTimeZone, toTimeZone)`..
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateOnly">The `DateOnly?` value to convert.</param>
+        /// <param name="fromTimeZone">The time zone to convert from.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateOnly? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateOnly? dateOnly,
+            string fromTimeZone,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateTime` value <paramref name="dateTime"/> from `@@session.time_zone` to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, @@session.time_zone, toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateTime">The `DateTime` value to convert.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateTime? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateTime dateTime,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateTimeOffset` value <paramref name="dateTimeOffset"/> from `+00:00`/UTC to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value as a `DateTime`.
+        ///     Corresponds to `CONVERT_TZ(dateTime, '+00:00', toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateTimeOffset">The `DateTimeOffset` value to convert.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted `DateTime?` value.</returns>
+        public static DateTime? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateTimeOffset dateTimeOffset,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateOnly` value <paramref name="dateOnly"/> from `@@session.time_zone` to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, @@session.time_zone, toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateOnly">The `DateOnly` value to convert.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateOnly? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateOnly dateOnly,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateTime?` value <paramref name="dateTime"/> from `@@session.time_zone` to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, @@session.time_zone, toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateTime">The `DateTime?` value to convert.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateTime? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateTime? dateTime,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateTimeOffset?` value <paramref name="dateTimeOffset"/> from `+00:00`/UTC to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value as a `DateTime`.
+        ///     Corresponds to `CONVERT_TZ(dateTime, '+00:00', toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateTimeOffset">The `DateTimeOffset?` value to convert.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted `DateTime?` value.</returns>
+        public static DateTime? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateTimeOffset? dateTimeOffset,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        /// <summary>
+        ///     Converts the `DateOnly?` value <paramref name="dateOnly"/> from `@@session.time_zone` to the time zone given by <paramref name="toTimeZone"/> and returns the resulting value.
+        ///     Corresponds to `CONVERT_TZ(dateTime, @@session.time_zone, toTimeZone)`.
+        /// </summary>
+        /// <param name="_">The DbFunctions instance.</param>
+        /// <param name="dateOnly">The `DateOnly?` value to convert.</param>
+        /// <param name="toTimeZone">The time zone to convert to.</param>
+        /// <returns>The converted value.</returns>
+        public static DateOnly? ConvertTimeZone(
+            [CanBeNull] this DbFunctions _,
+            DateOnly? dateOnly,
+            string toTimeZone)
+            => throw new InvalidOperationException(CoreStrings.FunctionOnClient(nameof(ConvertTimeZone)));
+
+        #endregion ConvertTimeZone
+
         /// <summary>
         ///     Counts the number of year boundaries crossed between the startDate and endDate.
         ///     Corresponds to TIMESTAMPDIFF(YEAR,startDate,endDate).

src/EFCore.MySql/Query/ExpressionTranslators/Internal/MySqlDbFunctionsExtensionsMethodTranslator.cs

@@ -11,6 +11,7 @@
 using Microsoft.EntityFrameworkCore.Query.SqlExpressions;
 using Microsoft.EntityFrameworkCore.Storage;
 using Pomelo.EntityFrameworkCore.MySql.Query.Internal;
+using Pomelo.EntityFrameworkCore.MySql.Utilities;
 
 namespace Pomelo.EntityFrameworkCore.MySql.Query.ExpressionTranslators.Internal
 {
@@ -22,6 +23,40 @@ public class MySqlDbFunctionsExtensionsMethodTranslator : IMethodCallTranslator
     {
         private readonly MySqlSqlExpressionFactory _sqlExpressionFactory;
 
+        private static readonly HashSet<MethodInfo> _convertTimeZoneMethodInfos =
+        [
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateTime), typeof(string), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateOnly), typeof(string), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateTime?), typeof(string), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateOnly?), typeof(string), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateTime), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateTimeOffset), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateOnly), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateTime?), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateTimeOffset?), typeof(string) }),
+            typeof(MySqlDbFunctionsExtensions).GetRuntimeMethod(
+                nameof(MySqlDbFunctionsExtensions.ConvertTimeZone),
+                new[] { typeof(DbFunctions), typeof(DateOnly?), typeof(string) }),
+        ];
+
         private static readonly Type[] _supportedLikeTypes = {
             typeof(int),
             typeof(long),
@@ -148,6 +183,29 @@ public virtual SqlExpression Translate(
             IReadOnlyList<SqlExpression> arguments,
             IDiagnosticsLogger<DbLoggerCategory.Query> logger)
         {
+            if (_convertTimeZoneMethodInfos.TryGetValue(method, out _))
+            {
+                // Will not just return `NULL` if any of its parameters is `NULL`, but also if `fromTimeZone` or `toTimeZone` is incorrect.
+                // Will do no conversion at all if `dateTime` is outside the supported range.
+                return _sqlExpressionFactory.NullableFunction(
+                    "CONVERT_TZ",
+                    arguments.Count == 3
+                        ?
+                        [
+                            arguments[1],
+                            // The implicit fromTimeZone is UTC for DateTimeOffset values and the current session time zone otherwise.
+                            method.GetParameters()[1].ParameterType.UnwrapNullableType() == typeof(DateTimeOffset)
+                                ? _sqlExpressionFactory.Constant("+00:00")
+                                : _sqlExpressionFactory.Fragment("@@session.time_zone"),
+                            arguments[2]
+                        ]
+                        : new[] { arguments[1], arguments[2], arguments[3] },
+                    method.ReturnType.UnwrapNullableType(),
+                    null,
+                    false,
+                    Statics.GetTrueValues(arguments.Count));
+            }
+
             if (_likeMethodInfos.Any(m => Equals(method, m)))
             {
                 var match = _sqlExpressionFactory.ApplyDefaultTypeMapping(arguments[1]);

test/EFCore.MySql.Tests/Query/MySqlTimeZoneTest.cs

@@ -0,0 +1,112 @@
+using System;
+using System.Linq;
+using Microsoft.EntityFrameworkCore;
+using Xunit;
+
+namespace Pomelo.EntityFrameworkCore.MySql.Query
+{
+    public sealed class MySqlTimeZoneTest : TestWithFixture<MySqlTimeZoneTest.MySqlTimeZoneFixture>
+    {
+        public MySqlTimeZoneTest(MySqlTimeZoneFixture fixture)
+            : base(fixture)
+        {
+        }
+
+        [ConditionalFact]
+        public void ConvertTimeZone()
+        {
+            using var context = Fixture.CreateContext();
+            SetSessionTimeZone(context);
+            Fixture.ClearSql();
+
+            var metalContainer = context.Set<Model.Container>()
+                .Where(c => c.DeliveredDateTimeOffset == c.DeliveredDateTimeUtc &&
+                            EF.Functions.ConvertTimeZone(c.DeliveredDateTimeOffset, c.DeliveredTimeZone) == c.DeliveredDateTimeLocal)
+                .Select(
+                    c => new
+                    {
+                        c.DeliveredDateTimeUtc,
+                        c.DeliveredDateTimeLocal,
+                        c.DeliveredDateTimeOffset,
+                        c.DeliveredTimeZone,
+                        DeliveredWithAppliedTimeZone = EF.Functions.ConvertTimeZone(c.DeliveredDateTimeOffset, c.DeliveredTimeZone),
+                        DeliveredConvertedToDifferent = EF.Functions.ConvertTimeZone(c.DeliveredDateTimeLocal, c.DeliveredTimeZone, "+06:00"),
+                    })
+                .Single();
+
+            Assert.Equal(MySqlTimeZoneFixture.OriginalDateTimeUtc, metalContainer.DeliveredDateTimeUtc);
+            Assert.Equal(MySqlTimeZoneFixture.OriginalDateTime, metalContainer.DeliveredDateTimeLocal);
+            Assert.Equal(MySqlTimeZoneFixture.OriginalDateTimeOffset, metalContainer.DeliveredDateTimeOffset);
+            Assert.Equal(MySqlTimeZoneFixture.OriginalDateTimeOffset.UtcDateTime, metalContainer.DeliveredDateTimeOffset.DateTime);
+            Assert.Equal(TimeSpan.Zero, metalContainer.DeliveredDateTimeOffset.Offset);
+            Assert.Equal(MySqlTimeZoneFixture.OriginalDateTime, metalContainer.DeliveredWithAppliedTimeZone);
+            Assert.Equal(MySqlTimeZoneFixture.OriginalDateTimeUtc.AddHours(6), metalContainer.DeliveredConvertedToDifferent);
+
+            Assert.Equal(
+                """
+SELECT `c`.`DeliveredDateTimeUtc`, `c`.`DeliveredDateTimeLocal`, `c`.`DeliveredDateTimeOffset`, `c`.`DeliveredTimeZone`, CONVERT_TZ(`c`.`DeliveredDateTimeOffset`, '+00:00', `c`.`DeliveredTimeZone`) AS `DeliveredWithAppliedTimeZone`, CONVERT_TZ(`c`.`DeliveredDateTimeLocal`, `c`.`DeliveredTimeZone`, '+06:00') AS `DeliveredConvertedToDifferent`
+FROM `Container` AS `c`
+WHERE (`c`.`DeliveredDateTimeOffset` = `c`.`DeliveredDateTimeUtc`) AND (CONVERT_TZ(`c`.`DeliveredDateTimeOffset`, '+00:00', `c`.`DeliveredTimeZone`) = `c`.`DeliveredDateTimeLocal`)
+LIMIT 2
+""",
+                Fixture.Sql);
+        }
+
+        private static void SetSessionTimeZone(MySqlTimeZoneFixture.MySqlTimeZoneContext context)
+        {
+            context.Database.OpenConnection();
+            var connection = context.Database.GetDbConnection();
+            using var command = connection.CreateCommand();
+            command.CommandText = "SET @@session.time_zone = '-08:00';";
+            command.ExecuteNonQuery();
+        }
+
+        public class MySqlTimeZoneFixture : MySqlTestFixtureBase<MySqlTimeZoneFixture.MySqlTimeZoneContext>
+        {
+            public const int OriginalOffset = 2; // UTC+2
+            public static readonly DateTime OriginalDateTimeUtc = new DateTime(2023, 12, 31, 23, 0, 0);
+            public static readonly DateTime OriginalDateTime = OriginalDateTimeUtc.AddHours(OriginalOffset);
+            public static readonly DateTimeOffset OriginalDateTimeOffset = new DateTimeOffset(OriginalDateTime, TimeSpan.FromHours(OriginalOffset));
+
+            public void ClearSql()
+                => base.SqlCommands.Clear();
+
+            public new string Sql
+                => base.Sql;
+
+            public class MySqlTimeZoneContext : ContextBase
+            {
+                protected override void OnModelCreating(ModelBuilder modelBuilder)
+                {
+                    modelBuilder.Entity<Model.Container>(
+                        entity =>
+                        {
+                            entity.HasData(
+                                new Model.Container
+                                {
+                                    Id = 1,
+                                    Name = "Heavymetal",
+                                    DeliveredDateTimeUtc = OriginalDateTimeUtc,
+                                    DeliveredDateTimeLocal = OriginalDateTime,
+                                    DeliveredDateTimeOffset = OriginalDateTimeOffset,
+                                    DeliveredTimeZone = "+02:00",
+                                });
+                        });
+                }
+            }
+        }
+
+        private static class Model
+        {
+            public class Container
+            {
+                public int Id { get ; set; }
+                public string Name { get ; set; }
+                public DateTime DeliveredDateTimeUtc { get; set; }
+                public DateTime DeliveredDateTimeLocal { get; set; }
+                public DateTimeOffset DeliveredDateTimeOffset { get; set; }
+                public string DeliveredTimeZone { get; set; }
+            }
+        }
+    }
+}