实体框架+ AutoMapper（实体到DTO和DTO到实体） [英] Entity Framework + AutoMapper ( Entity to DTO and DTO to Entity )

问题描述

我有使用EF与AutoMapper一些问题。 = /

I've got some problems using EF with AutoMapper. =/

例如：

我有2相关实体（Customers和Orders）
和他们DTO类：

I've got 2 related entities ( Customers and Orders ) and they're DTO classes :

class CustomerDTO
{
   public string CustomerID {get;set;}
   public string CustomerName {get;set;}
   public IList Orders {get;set;}
}

class OrderDTO
{
   public string OrderID {get;set;}
   public string OrderDetails {get;set;}
   public CustomerDTO Customers {get;set;}
}

//when mapping Entity to DTO the code works
Customers cust = getCustomer(id);
Mapper.CreateMap();
Mapper.CreateMap();
CustomerDTO custDTO = Mapper.Map(cust);

//but when i try to map back from DTO to Entity it fails with AutoMapperMappingException.
Mapper.Reset();
Mapper.CreateMap();
Mapper.CreateMap();
Customers customerModel = Mapper.Map(custDTO); // exception is thrown here

我是不是做错了什么？

Am I doing something wrong?

在此先感谢！

推荐答案

我已经是有关更新EntityCollection引用问题。 AutoMapper创建一个从DTO到实体映射时关系的新实例，并且不讨好EF

The problem I had was related to updates to EntityCollection references. AutoMapper creates a new instance of the relation when mapping from the DTO to the Entity, and that doesn't please the EF.

什么解决我的问题是配置AutoMapper使用我EntityCollection性能目标值。你的情况：

What solved my problem was configuring AutoMapper to use the destination value for my EntityCollection properties. In your case:

Mapper.CreateMap< CustomerDTO , Customers >().ForMember(c => c.Orders, o => o.UseDestinationValue());

AM这样就不会创建一个新的EntityCollection实例，将使用至极来了与原有客户实体。

That way AM will not create a new EntityCollection instance, and will use that wich came with the original Customer entity.

我还在工作的方式来自动完成这个，但现在它解决了我的问题。

I'm still working for a way to automate this, but for now it solves my problem.

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