WinFormDiApp/WinFormDiApp.DAL/ApplicationDbContext.cs

using Microsoft.EntityFrameworkCore.Design;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;
using WinFormDiApp.BL.Models;

namespace WinFormDiApp.DAL
{
    public class ApplicationDbContext : DbContext
    {
        public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options) { }

        public virtual DbSet<Member> Members { get; set; }
        public virtual DbSet<AccountRecord> AccountRecords { get; set; }

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<AccountRecord>()
                .HasIndex(e => new
                {
                    e.BetalDatum,
                    e.Belopp,
                    e.Konto
                })
                .IsUnique();
        }


    }


    public class DesignTimeDbContextFactory : IDesignTimeDbContextFactory<ApplicationDbContext>
    {
        public ApplicationDbContext CreateDbContext(string[] args)
        {
            IConfigurationRoot configuration = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile(@Directory.GetCurrentDirectory() + "/../WinFormDi/appsettings.json")
                .Build();
            var builder = new DbContextOptionsBuilder<ApplicationDbContext>();
            var connectionString = configuration.GetConnectionString("DatabaseConnection");
            builder.UseSqlite(connectionString);
            return new ApplicationDbContext(builder.Options);
        }
    }
}