Entity Framework Core and SQL Server 2016 temporal tables

Question

We are using EF Core and SQL Server 2016 for our .NET Core Web API. I am evaluating use of temporal tables and its impact on EF Core code. When I generate the EF model using cmdline then it generates model with appstart, append and mappings in dbcontext . When I do insert/update they fail saying these columns cannot be updated. I had to remove appstart, end from model and dbcontext mapping to make it work. I read there is no interception capability yet in EF Core like EF 6.x.

Please advise about any better solutions for this.

Answer 1

I tried below options and they are working.

1. option 1: removed appstart, append fields from entities and dbcontext mappings and updates/insert started working properly.

2. option 2: decorate period columns with attributes as below.

---

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime StartTime { get; set; }

[DatabaseGenerated(DatabaseGeneratedOption.Computed)]
public DateTime EndTime { get; set; } 

Answer 2

目前没有更好的解决方案，该功能在backlog 中。

Answer 3

Making the Period start column(StartTime) and Period end column(EndTime) hidden should fix this issue. We can do this by

ALTER TABLE [dbo].[Table1] ALTER COLUMN [StartTime] ADD HIDDEN;
ALTER TABLE [dbo].[Table1] ALTER COLUMN [EndTime] ADD HIDDEN;

We can see the settings for hidden against these columns in the sys.columns table

SELECT * FROM sys.columns WHERE is_hidden = 1 

Answer 4

I think there's a better solution for this as follows: Create partial context file (to prevent re-making the changes after re-generating the model) as follows

public partial class DatabaseDBContext : DbContext
{
    partial void OnModelCreatingPartial(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Table1>(entity =>
        {
            entity.Property(e => e.StartTime)
                .ValueGeneratedOnAddOrUpdate();
            entity.Property(e => e.EndTime)
                .ValueGeneratedOnAddOrUpdate();
        });
    }
}

Answer 5

.NET 6 and Entity Framework Core 6.0 supports SQL Server temporal tables out of the box.

See this answer for examples:

https://stackoverflow.com/a/70017768/3850405