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

After a lot of wasted time on research I've solved it absolutely unexpected. Actually, the solution to my problem lies on the surface, because the problem is not in EF and not in it's stuff. In my case it was SEQUENCE. I mean, involved table has serial column and related sequence just was changed by some side-effect. In another words - sequence was restarted from 1 and at the same time the table is already having values with 1, 2, 3 ... etc. That's why postgres throws 'duplicate key' error. So, the solution is:

ALTER SEQUENCE "your_table_seq" RESTART WITH your_value;