The milliseconds of `DateTime` are lost when adding data seeds in database migration.

[codelovercc]

Question

The milliseconds of DateTime are lost when adding data seeds in database migration. After saving to the database, the milliseconds of the DateTime type in all entity-generated data seeds are lost. However, the milliseconds of data added using DbContext.Add are normal.

public class MyEntity
{
    public Guid Id { get; set; }

    public DateTime CreationTime { get; set; }
    public DateTime UpdateTime { get; set; }
}

public class UtcDateTimeConverter : ValueConverter<DateTime, DateTime>
{
    public UtcDateTimeConverter() : base(d => d.ToUniversalTime(),
        d => DateTime.SpecifyKind(d, DateTimeKind.Utc))
    {
    }
}

Added migration code fregment in file Migration/20230719164925_Initial.cs :

migrationBuilder.InsertData(
                table: "MyEntity",
                columns: new[] { "Id", "CreationTime", "UpdateTime" },
                values: new object[,]
                {
                    { new Guid("05460fb9-dd73-4936-4c61-08db8b12aec2"), new DateTime(2023, 7, 22, 16, 40, 51, 613, DateTimeKind.Utc).AddTicks(9050),  new DateTime(2023, 7, 22, 16, 40, 51, 613, DateTimeKind.Utc).AddTicks(9050) },
                    { new Guid("d518683e-24f7-40c2-4c60-08db8b12aec2"), new DateTime(2023, 7, 22, 16, 40, 51, 613, DateTimeKind.Utc).AddTicks(9040), new DateTime(2023, 7, 22, 16, 40, 51, 613, DateTimeKind.Utc).AddTicks(9050) }
                });

As we can see, the DateTime contains the milliseconds.

Generated SQL script:

CREATE TABLE `MyEntity` (
    `Id` char(36) COLLATE ascii_general_ci NOT NULL,
    `CreationTime` datetime(6) NOT NULL,
    `UpdateTime` datetime(6) NOT NULL,
    CONSTRAINT `PK_MyEntity` PRIMARY KEY (`Id`)
) CHARACTER SET=utf8mb4;

INSERT INTO `MyEntity` (`Id`, `CreationTime`, `UpdateTime`)
VALUES ('cb0c4271-4ed1-4c5a-3077-08db7c5dfd15', TIMESTAMP '2023-07-04 07:12:13', TIMESTAMP '2023-07-04 07:12:13'),
('fe96bb85-7c49-4605-3076-08db7c5dfd15', TIMESTAMP '2023-07-04 07:12:13', TIMESTAMP '2023-07-04 07:12:13');

DateTime type is converted to TIMESTAMP, this may cause the issue. In table MyEntity, the type of column CreationTime is datetime(6)

Provider and version information

MySql: 5.7 EF Core version: 7.0.5 Database provider: Pomelo.EntityFrameworkCore.MySql 7.0.0 Target framework: .Net 7.0 Operating system: macOs Big Sur 11.7.7 IDE: JetBrains Rider 2023.1.3

[yukozh]

I saw some cases failed about this, will try to fix in 8.0