1. 假设存在以下实体类及其关系：

public class Order
{
    public int Id { get; set; }
    public ICollection OrderItems { get; set; }
}

public class OrderItem
{
    public int Id { get; set; }
    public int OrderId { get; set; }
    public int ProductId { get; set; }
    public Product Product { get; set; }
}

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
}

2. 创建DTO类，用于映射实体：

public class OrderDto
{
    public int Id { get; set; }
    public List OrderItems { get; set; }
}

public class OrderItemDto
{
    public int Id { get; set; }
    public int ProductId { get; set; }
    public ProductDto Product { get; set; }
}

public class ProductDto
{
    public int Id { get; set; }
    public string Name { get; set; }
}

3. 在Startup类中配置Automapper：

public void ConfigureServices(IServiceCollection services)
{
    services.AddAutoMapper(typeof(Startup));
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, IMapper mapper)
{
    mapper.ConfigurationProvider.AssertConfigurationIsValid();
    //...
}

4. 创建映射配置类：

public class OrderProfile : Profile
{
    public OrderProfile()
    {
        CreateMap()
            .ForMember(dest => dest.Product, opt => opt.MapFrom(src => src.Product));
        CreateMap()
            .ForMember(dest => dest.OrderItems, opt => opt.MapFrom(src => src.OrderItems))
            .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id));
        CreateMap()
            .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id))
            .ForMember(dest => dest.Name, opt => opt.MapFrom(src => src.Name));
    }
}

5. 通过Automapper进行转换：

var order = new Order
{
    Id = 1,
    OrderItems = new List
    {
        new OrderItem 
        {
            Id = 1,
            ProductId = 1,
            Product = new Product 
            {
                Id = 1,
                Name = "Product 1"
            }
        },
        new OrderItem 
        {
            Id = 2,
            ProductId = 2,
            Product = new Product 
            {
                Id = 2,
                Name = "Product