AutoMapper 9.0的改造（续）

上一篇有一个读者，有疑问，如何自动化注册Dto

我开篇，做了一个自动化注册的

    public sealed class AutoInjectAttribute : Attribute
    {
        public Type SourceType { get; }
        public Type TargetType { get; }

        public AutoInjectAttribute(Type sourceType, Type targetType)
        {
            SourceType = sourceType;
            TargetType = targetType;
        }
    }

增加了一个特性，在Dto上面打上，参数1是源类型，参数2是Dto类型

增加一个工厂类保存自动转换的类型

    public class AutoInjectFactory
    {
        public List<(Type,Type)> ConvertList { get; } = new List<(Type, Type)>();

        public void AddAssemblys(params Assembly[] assemblys)
        {
            foreach (var assembly in assemblys)
            {
                var atributes = assembly.GetTypes()
                    .Where(_type => _type.GetCustomAttribute<AutoInjectAttribute>() != null)
                    .Select(_type => _type.GetCustomAttribute<AutoInjectAttribute>());

                foreach (var atribute in atributes)
                {
                    ConvertList.Add((atribute.SourceType, atribute.TargetType));
                }
            }
        }
    }

在原来的AddAutoMapper上找到修改的代码段

        public static IServiceCollection AddAutoMapper(this IServiceCollection service)
        {
            ...略
            service.TryAddSingleton(serviceProvider =>
            {
                var mapperConfigurationExpression = serviceProvider.GetRequiredService<MapperConfigurationExpression>();

                var instance = new MapperConfiguration(mapperConfigurationExpression);

                instance.AssertConfigurationIsValid();

                return instance;
            });
            ...略

            return service;
        }

改为

        public static IServiceCollection AddAutoMapper(this IServiceCollection service)
        {
            ...略
            service.TryAddSingleton(serviceProvider =>
            {
                var mapperConfigurationExpression = serviceProvider.GetRequiredService<MapperConfigurationExpression>();
                var factory = serviceProvider.GetRequiredService<AutoInjectFactory>();

                foreach (var (sourceType,targetType) in factory.ConvertList)
                {
                    mapperConfigurationExpression.CreateMap(sourceType, targetType);
                }

                var instance = new MapperConfiguration(mapperConfigurationExpression);

                instance.AssertConfigurationIsValid();

                return instance;
            });
            ...略

            return service;
        }

增加一组扩展方法

    public static class AutoMapperExtension
    {
        ...略

        public static void UseAutoInject(this IApplicationBuilder applicationBuilder, params Assembly[] assemblys)
        {
            var factory = applicationBuilder.ApplicationServices.GetRequiredService<AutoInjectFactory>();

            factory.AddAssemblys(assemblys);
        }
    }