c# - 如何全局忽略映射源空值？

Question

有没有办法全局(对于所有映射配置)忽略空值到目标的映射？

这里有一些东西:

    //Automapper config
    Mapper.Initialize(cfg =>
    {
        //Initializes all mapping profiles in the assembly
        cfg.AddProfiles(Assembly.GetExecutingAssembly().GetName().Name);

        //If map is called without a profile creates default map
        cfg.CreateMissingTypeMaps = true;
    });

这是例如映射。这是我正在努力完成的一个例子。

//Models
    class User {
      public string Name {get; set;}
      public string Email {get; set;}
      public string Password {get; set;}
    }

    class UserDto {
      public string Name {get; set;}
      public string Email {get; set;}
    }

//Start instances
     var user = new User { Name = "John", Email = "john@live.com", Password = "123"};

     var userDto = new UserDto { Name = "Tim" };
//Notice that we left the Email null on the DTO


//Mapping
    Mapper.Map(userDto, user);

结果以用户收到空电子邮件而告终。我希望用户电子邮件不会更改，除非在源 (userDto) 上提供了新电子邮件。换句话说，忽略所有类型的所有空属性覆盖目标(用户)的源对象

更新:以下所有答案均无法解决问题。它们根本不适用于收藏。虽然 Autommaper 找出了这个错误，但我能够通过使用 ExpandoObject 在映射之前过滤掉所有空属性来解决我的问题，如下所示:

var patchInput = new ExpandoObject() as IDictionary<string, object>;

foreach (var property in userDto.GetType().GetProperties())
    if (property.GetValue(userDto) is var propertyValue && propertyValue != null)
        patchInput.Add(property.Name, propertyValue);

Mapper.Map(patchInput, user);

Answer 1

应该可以的

Mapper.Initialize(cfg =>
        {
            cfg.AddProfiles(Assembly.GetExecutingAssembly().GetName().Name);
            cfg.CreateMissingTypeMaps = true;
            cfg.ForAllMaps((typeMap, map) =>
                map.ForAllMembers(option => option.Condition((source, destination, sourceMember) => sourceMember != null)));
        });