Program.cs

using Microsoft.EntityFrameworkCore;
using PokemonReviewApp;
using PokemonReviewApp.Data;
using PokemonReviewApp.Interfaces;
using PokemonReviewApp.Repository;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllers();

//add the dependency injection  of seed class at first when the app starts  i.e creating object for the Seed class
builder.Services.AddTransient<Seed>();

//add automapper for DTO
builder.Services.AddAutoMapper(AppDomain.CurrentDomain.GetAssemblies());

// dependency injection for all the classes you have created
builder.Services.AddScoped<IPokemonRepository, PokemonRepository>();
builder.Services.AddScoped<ICategoryRepository, CategoryRepository>();
builder.Services.AddScoped<ICountryRepository, CountryRepository>();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

//Add SQL Server
builder.Services.AddDbContext<DataContext>(options =>
{
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"));
});

var app = builder.Build();

// if you want to perpopulate the database with seed from args with command as follows
// dotnet run seeddata from command line

if (args.Length == 1 && args[0].ToLower() == "seeddata")
    SeedData(app);

void SeedData(IHost app)
{
    var scopedFactory = app.Services.GetService<IServiceScopeFactory>();

    using (var scope = scopedFactory.CreateScope())
    {
        var service = scope.ServiceProvider.GetService<Seed>();
        service.SeedDataContext();
    }
}
//end of propoulation service

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();