Migration conflicts in net core Entity Framework - sql-server

Question

I have two tables in my SQL Server database - one for categories:
public class Category
{
public int Id { get; set; }
public string Name { get; set; }
public int? ParentId { get; set; }
[ForeignKey("ParentId")]
public Category Parent { get; set; }
}
And then the Assistant table:
public class Assistant
{
public int Id { get; set; }
public int UserId { get; set; }
public DateTime CreatedAtUtc { get; set; }
public Status Status { get; set; }
public int? CategoryId { get; set; }
[ForeignKey("CategoryId")]
public Category Category { get; set; }
}
When I try to make a migration I get this error:
The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_Assistants_Categories_CategoryId". The conflict occurred in database "Pirma
isMsSql", table "dbo.Categories", column 'Id'.
I have no idea why.
Thanks

Answer 1

Fix your classes:
public partial class Assistent
{
[Key]
public int Id { get; set; }
public int UserId { get; set; }
public User User{ get; set; }
public DateTime CreatedAtUtc { get; set; }
public int StatusId { get; set; }
public Status Status { get; set; }
public int? CategoryId { get; set; }
[ForeignKey(nameof(CategoryId))]
[InverseProperty("Assistents")]
public virtual Category Category { get; set; }
}
public partial class Category
{
[Key]
public int Id { get; set; }
public string Name { get; set; }
public int? ParentId { get; set; }
[ForeignKey(nameof(ParentId))]
[InverseProperty(nameof(Category.InverseParent))]
public virtual Category Parent { get; set; }
[InverseProperty(nameof(Assistent.Category))]
public virtual ICollection<Assistent> Assistents { get; set; }
[InverseProperty(nameof(Category.Parent))]
public virtual ICollection<Category> InverseParent { get; set; }
}
This is db context:
public partial class AssistentsContext : DbContext
{
public AssistentsContext()
{
}
public AssistentsContext(DbContextOptions<AssistentsContext> options)
: base(options)
{
}
public virtual DbSet<Assistent> Assistents { get; set; }
public virtual DbSet<Category> Categories { get; set; }
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Assistent>(entity =>
{
entity.HasOne(d => d.Category)
.WithMany(p => p.Assistents)
.HasForeignKey(d => d.CategoryId);
});
modelBuilder.Entity<Category>(entity =>
{
entity.HasOne(d => d.Parent)
.WithMany(p => p.InverseParent)
.HasForeignKey(d => d.ParentId);
});
OnModelCreatingPartial(modelBuilder);
}
partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}