An ID number cannot be created in the database if it is auto generated by newid() InSqlserver with EF6

Question

I created a column in a table named [Id] and made its type nvarchar(50), and its value is automatically by newid(), which is a mixture of letters and numbers, when adding a new record inside the database through a (sql server managment) , the new number does not appear until I execute the table.

The problem is not here, the real problem is when creating a new record from within EF6, the record cannot be added without specifying the identity value, and the following message appears:

The key field 'Id' cannot have a value of null. A non-null value is required for the key fields defined on type 'Booking'.

this code for sqlserver table

CREATE TABLE [dbo].[TableName](
    [id] [varchar](10) NOT NULL,
    [Price] [nvarchar](10) NULL,
PRIMARY KEY CLUSTERED 
(
    [id] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON, OPTIMIZE_FOR_SEQUENTIAL_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
GO

ALTER TABLE [dbo].[TableName] ADD  DEFAULT (concat(left(newid(),(4)),'-',abs(checksum(newid()))%(10000))) FOR [id]
GO

In Ef6 Use Code

context Db = new context ();
t TableName = new TableName{
Price=10
};
db.TableName.add(t);
db.SaveChanges();

Answer 1

you must add this code on Migration Class(My DbMigration's name is Initial) before level add-migration

this is code for only EF Classic

, defaultValueSql: "concat(left(newid(),(4)),'-',abs(checksum(newid()))%(10000))"

My class DbMigration

using System.Data.Entity.Migrations;
  
  public partial class Initial : DbMigration
  {
      public override void Up()
      {  CreateTable(
              "dbo.TableNames",
              c => new
                  {  Id = c.String(nullable: false, maxLength: 100, defaultValueSql: "concat(left(newid(),(4)),'-',abs(checksum(newid()))%(10000))"),
                      Price = c.String(maxLength: 100),
                  })  .PrimaryKey(t => t.Id);
            }
      
      public override void Down()
      {  DropTable("dbo.TableNames"); }
  }

my class :

public class TableName
{ 
    [Key]
    [MaxLength(100)]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public string Id { get; set; }

    [MaxLength(100)]
    public string Price { set; get; }
}

my DbContext:

public class MyContext : DbContext
{
    public MyContext()
        : base("Name=ConnectionString")
    { }
    public DbSet<TableName> TableName { get; set; }
    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {   base.OnModelCreating(modelBuilder); }
 }

add TableName

var Db = new MyContext();
var TableName = new TableName{ Price = "40"};
Db.TableName.Add(TableName);
Db.SaveChanges();

my Package:

• EntityFramework:6.4.4