How to set NewId() for GUID in entity framework

Question

I am creating asp.net mvc4 sample.In this i created Id column as GUID in Sample table of datacontext.

public class Sample
{
    [Required]
    public Guid          


        

Answer 1

When using Entity Framework Core 2.1.1 I use:

[Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
public Guid UserId { get; set; }

Then in the migration, add in the defaultValueSql parameter as below:

migrationBuilder.CreateTable(
    name: "Users",
    columns: table => new
    {
         UserId = table.Column(nullable: false, defaultValueSql: "newsequentialid()"),
         DisplayName = table.Column(nullable: true)
    },
       constraints: table =>
    {
        table.PrimaryKey("PK_Users", x => x.UserId);
    });

This ensures that the sql server is responsible for generating a sequential guid which is going to be better than rolling your own.

If you do not want the downsides of using sequential guids you can use "newid()" instead.