Startup.cs

using LibraryManagementSystem.Data;
using LibraryManagementSystem.Domain;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace LibraryManagementSystem
{
    public class Startup
    {
        
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddControllersWithViews()
                .AddJsonOptions(jsonOptions => 
                {
                    jsonOptions.JsonSerializerOptions.PropertyNamingPolicy = null;
                });

            services.AddDbContextPool<ApplicationContext>(dbcontextOptions => {

                dbcontextOptions.UseSqlServer("Server=.;Database=LibMgmtDb;Trusted_Connection=True;MultipleActiveResultSets=True");
            
            });

            services.AddIdentity<ApplicationUser, IdentityRole<int>>()
                .AddEntityFrameworkStores<ApplicationContext>()
                .AddDefaultTokenProviders();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }

            app.UseStaticFiles();
            app.UseRouting();

            app.UseAuthentication();
            app.UseAuthentication();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapDefaultControllerRoute();
            });
        }
    }
}