如何通过反射向Action列表添加方法？.NET实体创建日志场景

我有大量继承自泛型基类Business<T>的业务类，希望为它们动态添加实体创建后的日志记录逻辑——具体来说，就是把LogAugmenter.LogCreation方法添加到每个业务类的静态PostCreationAugmenters列表中。以下是我的代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

var businessClasses = typeof(IEntity)
    .Assembly
    .GetTypes()
    .ToList()
    .Where(i => i.BaseType != null)
    .Where(i => i.BaseType.Name.StartsWith("Business"))
    .ToList();
Console.WriteLine(businessClasses.Count);
foreach (var businessClass in businessClasses)
{
    var postCreationAugmenters = businessClass.GetField("PostCreationAugmenters", BindingFlags.FlattenHierarchy | BindingFlags.Public | BindingFlags.Static).GetValue(null);
    // how can I add the LogAugmenter.LogCreation to the postCreationAugmenters list?
}

public static class LogAugmenter
{
    public static void LogCreation(IEntity entity)
    {
    }
}


public interface IEntity
{
    long Id { get; set; }
}

public class Blog : IEntity
{
    public long Id { get; set; }
}

public class Business<T>
    where T : IEntity
{
    public static List<Action<T>> PostCreationAugmenters = new List<Action<T>>();
    public T Create(T entity)
    {
        // Inserting the model inside the database and returning it with the assigned Id
        foreach (var augmenter in PostCreationAugmenters)
        {
            augmenter.Invoke(entity);
        }

        return entity;
    }
}

public class BlogBusiness : Business<Blog>
{
    
}

解决方案 #

要实现需求，需要通过反射完成三个核心步骤：提取泛型参数、转换匹配委托、添加到目标列表。修改后的循环代码如下：

foreach (var businessClass in businessClasses)
{
    // 1. 获取基类的泛型参数T（如Blog）
    var genericBaseType = businessClass.BaseType;
    var entityType = genericBaseType.GetGenericArguments()[0];

    // 2. 获取PostCreationAugmenters静态字段
    var field = genericBaseType.GetField("PostCreationAugmenters", BindingFlags.Public | BindingFlags.Static);
    var augmenterList = field.GetValue(null) as IList;

    // 3. 将LogCreation转换为匹配的Action<T>委托
    var logMethod = typeof(LogAugmenter).GetMethod("LogCreation", BindingFlags.Public | BindingFlags.Static);
    var actionDelegate = Delegate.CreateDelegate(
        typeof(Action<>).MakeGenericType(entityType),
        logMethod
    );

    // 4. 添加到列表
    augmenterList.Add(actionDelegate);
}

关键细节说明

• 直接从泛型基类Business<T>获取静态字段：因为静态字段属于泛型构造体（如Business<Blog>），而非子类BlogBusiness
• 使用Delegate.CreateDelegate完成委托类型转换：由于T实现了IEntity，将Action<IEntity>转为Action<T>是安全的
• 借助IList接口统一处理：避免为每种实体类型编写特定的类型逻辑

完整可运行代码 #

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

var businessClasses = typeof(IEntity)
    .Assembly
    .GetTypes()
    .Where(i => i.BaseType != null && i.BaseType.IsGenericType && i.BaseType.GetGenericTypeDefinition() == typeof(Business<>))
    .ToList();

Console.WriteLine($"找到{businessClasses.Count}个业务类");

foreach (var businessClass in businessClasses)
{
    var genericBaseType = businessClass.BaseType;
    var entityType = genericBaseType.GetGenericArguments()[0];

    var field = genericBaseType.GetField("PostCreationAugmenters", BindingFlags.Public | BindingFlags.Static);
    var augmenterList = field.GetValue(null) as IList;

    var logMethod = typeof(LogAugmenter).GetMethod("LogCreation", BindingFlags.Public | BindingFlags.Static);
    var actionDelegate = Delegate.CreateDelegate(
        typeof(Action<>).MakeGenericType(entityType),
        logMethod
    );

    augmenterList.Add(actionDelegate);
}

// 测试日志逻辑
var blogBusiness = new BlogBusiness();
var blog = new Blog { Id = 1 };
blogBusiness.Create(blog);

public static class LogAugmenter
{
    public static void LogCreation(IEntity entity)
    {
        Console.WriteLine($"已记录实体创建日志：{entity.GetType().Name}（ID：{entity.Id}）");
    }
}

public interface IEntity
{
    long Id { get; set; }
}

public class Blog : IEntity
{
    public long Id { get; set; }
}

public class Business<T> where T : IEntity
{
    public static List<Action<T>> PostCreationAugmenters = new List<Action<T>>();
    public T Create(T entity)
    {
        // 模拟数据库插入逻辑
        foreach (var augmenter in PostCreationAugmenters)
        {
            augmenter.Invoke(entity);
        }

        return entity;
    }
}

public class BlogBusiness : Business<Blog> { }

内容的提问来源于stack exchange，提问作者Sharif Rezvani