Entity Framework Code First Using One column as Primary Key and another as Auto Increment Column

Question

I have a class named Sale

public class Sale
{
    public int Id { get; set; }
    public string TrNo { get; set; }
    public DateTime Date          


        

Answer 1

I believe you can do this using Fluent API

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Entity<Sale>().Property(a => a.Id).HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity);
    modelBuilder.Entity<Sale>().Property(a => a.TrNo).HasKey(b => b.TrNo);
}

Answer 2

This helped me. Hope this helps anyone else that still looking around

public class Sale
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]//switch on autogenerated
        public int Id { get; set; }

        [Key]//set as Primary key
        [DatabaseGenerated(DatabaseGeneratedOption.None)]// switch off autogenerated PK
        public string TrNo { get; set; }

        public DateTime Date { get; set; }
        public int CustomerID { get; set; }

        public ObservableCollection<SaleDetail> SaleDetails { get; set; }
}

Answer 3

You can also do this with Data Annotations:

public class Sale
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Key]
    public string TrNo { get; set; }

    public DateTime Date { get; set; }
    public int CustomerID { get; set; }

    public ObservableCollection<SaleDetail> SaleDetails { get; set; }
}

Answer 4

Apparently the answer of @IronMan84 correct. But it didn't work for me. I slightly modified it to apply my another condition. And it worked. I did nothing else.

This is my solution.

public class Sale
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [Key, Column(TypeName = "varchar"), MaxLength(50)]
    public string TrNo { get; set; }

    public DateTime Date { get; set; }
    public int CustomerID { get; set; }

    public ObservableCollection<SaleDetail> SaleDetails { get; set; }
}

Unfortunately I can't make the answer of @IronMan84 as the correct one as it didn't work for me.