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));
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