Override sql default value on insert using Entity Framework Core (7)

问题

I have a table with a column [CreatedAtIsoUtc] that sets a Sql Server default value

migrationBuilder.CreateTable(
            name: "CurrentAccountLedger",
            columns: table => new
            {
                Id = table.Column<Guid>(nullable: false, defaultValueSql: "newsequentialid()"),
                CreatedAtIsoUtc = table.Column<DateTime>(nullable: false, defaultValueSql: "GETUTCDATE()"),                    
            }

        });

In a raw sql server query, I can insert a record and overwrite the [CreatedAtIsoUtc] default value.

In Entity Framework, I can't seem to overwrite this value when performing an Add() operation.

Any ideas on how I could get this working?

回答1:

Actually in EF Core v1.1.0 you can do that by setting the property to any value different than the default for the type (i.e. 0 for numbers, false for bool, null for string and nullable types, default(DateTime) in your case). The only current limitation is that you cannot override the sql default value with 0, false, null etc.

For instance

db.CurrentAccountLedger.Add(new CurrentAccountLedger { });

would insert a record with CreatedAtIsoUtc equals to the default GETUTCDATE(), while

db.CurrentAccountLedger.Add(new CurrentAccountLedger { CreatedAtIsoUtc = new DateTime(2017, 1, 1) });

would insert a record with the specified value.

回答2:

You can set raw SQL defaults on your entities in your context's OnModelCreating() using HasDefaultValueSql():

class YourContext : DbContext
{
    public DbSet<CurrentAccountLedger> CurrentAccountLedgers { get; set; }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<CurrentAccountLedger>()
            .Property(x => x.CreatedAtIsoUtc)
            .HasDefaultValueSql("GETUTCDATE()");
    }
}

来源：https://stackoverflow.com/questions/41668301/override-sql-default-value-on-insert-using-entity-framework-core-7