思考一种好的架构（三）

这节说下最最最核心的库

数据持久化ORM 

其实还有很多关键点没说，但是我都跳过了，先说实现场景，再说架构，由浅入深

这里我使用的是Chloe.ORM，用起来比较顺手，也很轻，便于扩展，没有太大的问题，可以很方便的做事件(读写分离)CQRS,（工作单元）WorkOfUnit

 /// <summary>
    /// 单次请求中DC上下配置对象
    /// </summary>
    public interface IDCScoped: IDbConnectionFactory
    {
        /// <summary>
        /// 数据库连接字符串
        /// </summary>
        string ConnectionString { get; }

        /// <summary>
        /// 操作类型
        /// </summary>
        DCOperationType OperationType { get; }

        /// <summary>
        /// 选择操作类型
        /// </summary>
        /// <param name="connectionString"></param>
        /// <param name="operationType"></param>
        void SelectOpeation(string connectionString, DCOperationType operationType);



    }

 /// <summary>
    /// 数据库范围
    /// </summary>
    public class DCScope : IDCScoped
    {
        /// <summary>
        /// 数据库连接上下字符串
        /// </summary>
        public string ConnectionString { get;private set; }
        /// <summary>
        /// 操作类型
        /// </summary>
        public DCOperationType OperationType { get; private set; }

        /// <summary>
        /// 创建DC
        /// </summary>
        /// <returns></returns>
        public IDbConnection CreateConnection()
        {
            return new MySqlConnection(ConnectionString);
        }
        /// <summary>
        /// 选择操作
        /// </summary>
        /// <param name="connectionString"></param>
        /// <param name="operationType"></param>
        public void SelectOpeation(string connectionString, DCOperationType operationType)
        {
            this.ConnectionString = connectionString;
            this.OperationType = operationType;
        }
    }
    /// <summary>
    /// DC操作类型
    /// </summary>
    public enum DCOperationType {
        /// <summary>
        /// 读操作
        /// </summary>
        Query = 0,
        /// <summary>
        /// 写操作
        /// </summary>
        Command=1
    }

 public static class IQueryExtend
    {
        public static IQuery<T> EmptyCheck<T>(this IQuery<T> query,object judgeValue, Expression<Func<T, bool>> predicate) {
            if (judgeValue!=null)
            {
               return query.Where(predicate);
            }
            return query;
        }
    }

这个只是一个非空判断的扩展Where方法，单独写出来只是为了表示Chloe.ORM一切都归它管，扩展方法也是

 public static class Startup
    {
        public static void ConfigureServices(IServiceCollection services)
        {
            services.AddScoped<IDCScoped, DCScope>();
            services.AddScoped<IDbContext>(x=> new MySqlContext(x.GetService<IDCScoped>()));
        }

        public static void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
        }
    }

这个注入了IDScoped对象和IDbContext对象

IDScoped 是保存每次需要数据库的信息

ORM.Chloe.DoMain 

负责维护一个数据库上下文和它的生命周期，Chloe.ORM的扩展也归它管，但是具体要选哪个数据库创建对象就不归它管了，谁爱管谁管，反正我不负责选则数据库的业务