Entity Framework Core and SQL Server 2016 temporal tables

问题

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.

回答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; } 

回答2:

There currently is no better solution for this, and the feature is on the backlog.

回答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 

回答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();
        });
    }
}

来源：https://stackoverflow.com/questions/42627585/entity-framework-core-and-sql-server-2016-temporal-tables