How to tell Entity Framework that my ID column is auto-incremented (AspNet Core 2.0 + PostgreSQL)?

Question

Code is simple. Tag.cs entity:

public partial class Tag
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { ge         


        

Answer 1

You have to use here "ValueGenerationOnAdd()". As the issue you are getting is already reported on GitHub. Please find the below link.

https://github.com/npgsql/Npgsql.EntityFrameworkCore.PostgreSQL/issues/73

You can find more info regarding Generated Value pattern from following link.

Value generated on add

public classs SampleContext:DBContext{
public DbSet Tag { get; set; }

protected override void OnModelCreating(ModelBuilder modelBuilder){
    modelBuilder.Entity()
        .Property(p => p.ID)
        .ValueGeneratedOnAdd();
 }
public class Tag{
  public int Id { get; set; }
  public string Name { get; set; }
  public string Description{get;set;}
  }
}

Source:- https://www.learnentityframeworkcore.com/configuration/fluent-api/valuegeneratedonadd-method

Hope this will help