我正在使用Automapper在Entity和viewmodel对象之间进行映射(在两个方向上).该模型使用EF4 DbContext POCO并需要启用LazyLoading(因此代理生成).
我在尝试从viewmodel更新现有实体时遇到了问题.当我调用Mapper.Map(vm,entity)时,Automapper会抛出异常.我的问题是：你如何使用Automapper使用EF代理对象？
代码看起来(简化)像这样：
public class MyEntity
{
public int Id {get;set;}
public int Name {get;set;}
}
public class viewmodel
{
public int Id {get;set;}
public int Name {get;set;}
}
Mapper.CreateMap<MyEntity,viewmodel>();
Mapper.CreateMap<viewmodel,MyEntity>();
public ActionResult Edit(viewmodel vm)
{
MyEntity entity = db.MyEntities.Find(vm.Id);
Mapper.Map(vm,entity);
db.Entry(entity).State = EntityState.Modified;
db.SaveChanges();
}
当我调用Mapper.Map(vm,entity)来更新现有的实体对象时,我得到了异常：
'Mapper.Map(viewmodel,resultSet)' threw an exception of type 'AutoMapper.AutoMapperMappingException' base {System.Exception}: {"Missing type map configuration or unsupported mapping.\n\nMapping types:\r\nResultSetView -> ResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2\r\nSciensus.Applications.ClinicalStudies.Web.Areas.Patient.Models.ResultSetView -> System.Data.Entity.DynamicProxies.ResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2\n\nDestination path:\nResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2\n\nSource value:\nSciensus.Applications.ClinicalStudies.Web.Areas.Patient.Models.ResultSetView"} Context: {Trying to map ResultSetView to ResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2.} Message: "Missing type map configuration or unsupported mapping.\n\nMapping types:\r\nResultSetView -> ResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2\r\nSciensus.Applications.ClinicalStudies.Web.Areas.Patient.Models.ResultSetView -> System.Data.Entity.DynamicProxies.ResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2\n\nDestination path:\nResultSet_692D75838D4DC59B922F3E88CF1B10516CBF6CD8A32C4BE2F3FCC28CE83F0BD2\n\nSource value:\nSciensus.Applications.ClinicalStudies.Web.Areas.Patient.Models.ResultSetView" StackTrace: ""
解决方法
我查看了AutoMapper源代码：
public TDestination Map<TSource,TDestination>(TSource source,TDestination destination)
{
return Map(source,destination,opts => { });
}
public TDestination Map<TSource,TDestination destination,Action<IMappingOperationOptions> opts)
{
Type modelType = typeof(TSource);
Type destinationType = (Equals(destination,default(TDestination)) ? typeof(TDestination) : destination.GetType());
return (TDestination)Map(source,modelType,destinationType,opts);
}
这个地方出现了问题：
Type destinationType = (Equals(destination,default(TDestination)) ? typeof(TDestination) : destination.GetType());
所以没有问题的变化：
Mapper.Map(vm,entity,typeof(viewmodel),typeof(MyEntity));
