DbLibraryContext.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;

namespace Library.Model
{
    public class DbLibraryContext : DbContext
    {
        public DbSet<Book> Books { get; set; }
        public DbSet<Author> Authors { get; set; }
        public DbSet<Reader> Readers { get; set; }
        public DbSet<PublishingHouse> PublishingHouses { get; set; }
        public DbSet<Borrow> Borrows { get; set; }
        public DbSet<User> Users { get; set; }

        public DbLibraryContext() { }
        public DbLibraryContext(DbContextOptions<DbLibraryContext> options) : base(options)
        {
            
        }
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            optionsBuilder.UseSqlServer("Data Source=(localdb)\\MSSQLLocalDB;Initial Catalog=Library;Integrated Security=True;Connect Timeout=30;Encrypt=False;Trust Server Certificate=False;Application Intent=ReadWrite;Multi Subnet Failover=False");
        }

        protected override void OnModelCreating(ModelBuilder builder)
        {
            builder.Entity<User>()
                .HasIndex(user => user.Username)
                .IsUnique();
        }
    }
}