使用 automapper 更新实体框架实体

Question

我正在尝试使用实体框架并让 Automapper 从我的合同中更新我的实体。

我的代码如下所示：

var temp = OrderContract;
Order order = dataAccess.FindOne<Order>(x => x.OrderId == temp.OrderId) 
              ?? new Order();

Mapper.Map(OrderContract, order);

if (order.OrderId <= 0)
   dataAccess.Add(order);

（注意：我正在使用存储库模式。dataAccess.FindOne 调用 CreateQuery 返回一个实体。）

我遇到的问题在于关系。当我进行更新时出现此错误（插入工作正常）：

操作失败：无法更改关系，因为一个或多个外键属性不可为空。当关系发生更改时，相关的外键属性将设置为空值。如果外键不支持空值，则必须定义新的关系，必须为外键属性分配另一个非空值，或者必须删除不相关的对象。

我猜测自动映射器没有按照我想要的方式更新。从错误消息和谷歌搜索中，我猜测我的关系是集合（甚至可能不是集合）正在由 Automapper 重新创建。

如何告诉 Automapper 仅更新而不重新创建任何对象或集合？

猜测：

我读到也许我需要使用 UseDestinationValue 选项对于自动映射器。我回去并将其放在我的所有集合中但是当我这样做时，我的插入会因外键违规而失败。

代码映射：

仅在一个集合上使用 UseDestinationValue（该集合会插入但不会更新）：

//+ Source
Mapper.CreateMap<SourceContract, Source>()
    .IgnoreAllNonExisting();

//+ SelectedRequirement
Mapper.CreateMap<SelectedRequirementContract, SelectedRequirement>()
    .ForMember(x => x.SelectedRequirementId, opt => opt.MapFrom(src => src.RequirementId))
    .IgnoreAllNonExisting();

//+ Comment Contract
Mapper.CreateMap<CommentContract, Comment>()
    .ForMember(x => x.CommentText, opt => opt.MapFrom(src => src.Comment))
    .IgnoreAllNonExisting();

//+ Order Automapper setup
Mapper.CreateMap<OrderContract, Order>()
    .ForMember(x => x.Source, opt => opt.MapFrom(src => src.Source))
    .ForMember(x => x.Comment, opt => opt.MapFrom(src => src.Comment))
    //Although a mapping was created for Comment entity,
    //we still need to map the CommentId of the Order entity otherwise it will remain null during an update.
    //Another way to handle this would be to Delete CommentId from the Order entity.
    //However, if anyone updates (Update from model) OrderDataModel.edmx that property would show up again thus causing
    //a null value to be inserted during an update.
    .ForMember(x => x.CommentId, opt => opt.MapFrom(src => src.Comment.CommentId))
    .ForMember(x => x.SelectedRequirements, opt => {opt.UseDestinationValue(); opt.MapFrom(src => src.Requirements);})
    .ForMember(x => x.OrderStateId, opt => opt.MapFrom(src => src.StateId))
    .ForMember(x => x.OrderStateId, opt => opt.MapFrom(src => src.StateId))
    .IgnoreAllNonExisting();

在任何地方都使用 UseDestinationValue（该集合不会插入）：

//+ Source
Mapper.CreateMap<SourceContract, Source>()
    .IgnoreAllNonExisting();

//+ SelectedRequirement
Mapper.CreateMap<SelectedRequirementContract, SelectedRequirement>()
    .ForMember(x => x.SelectedRequirementId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.RequirementId); })
    .IgnoreAllNonExisting();

//+ Comment Contract
Mapper.CreateMap<CommentContract, Comment>()
    .ForMember(x => x.CommentText, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Comment); })
    .IgnoreAllNonExisting();

//+ Order Automapper setup
Mapper.CreateMap<OrderContract, Order>()
    .ForMember(x => x.Source, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Source); })
    .ForMember(x => x.Comment, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Comment); })
    //Although a mapping was created for Comment entity,
    //we still need to map the CommentId of the Order entity otherwise it will remain null during an update.
    //Another way to handle this would be to Delete CommentId from the Order entity.
    //However, if anyone updates (Update from model) OrderDataModel.edmx that property would show up again thus causing
    //a null value to be inserted during an update.
    .ForMember(x => x.CommentId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Comment.CommentId); })
    .ForMember(x => x.SelectedRequirements, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.Requirements); })
    .ForMember(x => x.OrderStateId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.StateId); })
    .ForMember(x => x.OrderStateId, opt => { opt.UseDestinationValue(); opt.MapFrom(src => src.StateId); })
    .IgnoreAllNonExisting();

我需要做什么才能插入和更新？

Answer 1

我认为您想要的是 AutoMapper 不创建您的 EF 实体并获取您发送的实体。在自动映射器的 version2.0 中，有一个重载的映射方法，您基本上可以传递数据上下文委托并让 EF 创建您的对象。

请查看这篇文章。