AutoMapper：保留目標值，如果該屬性不存在於源

Question

我試圖搜索很多，並嘗試不同的選項，但似乎沒有任何工作。

我使用ASP.net身份2.0，我有UpdateProfileViewModel。更新用戶信息時，我想將UpdateProfileViewModel映射到ApplicationUser（即身份模型）;但我想保留這些值，我從用戶的數據庫中獲得了這些值。即用戶名&電子郵件地址，不需要更改。

我試圖做：

Mapper.CreateMap<UpdateProfileViewModel, ApplicationUser>() 
.ForMember(dest => dest.Email, opt => opt.Ignore()); 

，但我仍然獲得電子郵件爲空映射後：

var user = await UserManager.FindByIdAsync(User.Identity.GetUserId()); 
user = Mapper.Map<UpdateProfileViewModel, ApplicationUser>(model); 

我也試過，但沒有作品：

public static IMappingExpression<TSource, TDestination> IgnoreAllNonExisting<TSource, TDestination>(this IMappingExpression<TSource, TDestination> expression) 
    { 
     var sourceType = typeof(TSource); 
     var destinationType = typeof(TDestination); 
     var existingMaps = Mapper.GetAllTypeMaps().First(x => x.SourceType.Equals(sourceType) && x.DestinationType.Equals(destinationType)); 
     foreach (var property in existingMaps.GetUnmappedPropertyNames()) 
     { 
      expression.ForMember(property, opt => opt.Ignore()); 
     } 
     return expression; 
    } 

然後：

Mapper.CreateMap<UpdateProfileViewModel, ApplicationUser>() 
.IgnoreAllNonExisting(); 

Answer 1

所有你需要的是創造你的源和目標類型之間的映射：

Mapper.CreateMap<UpdateProfileViewModel, ApplicationUser>(); 

，然後執行映射：

UpdateProfileViewModel viewModel = ... this comes from your view, probably bound 
ApplicationUser user = await UserManager.FindByIdAsync(User.Identity.GetUserId()); 
Mapper.Map(viewModel, user); 

// at this stage the user domain model will only have the properties present 
// in the view model updated. All the other properties will remain unchanged 
// You could now go ahead and persist the updated 'user' domain model in your 
// datastore