使用AutoMapper映射未知类型 [英] Using AutoMapper to map unknown types

问题描述

我正在使用 AutoMapper 将一个对象的属性复制到另一个对象：这是我的代码：

I'm using AutoMapper to copy the properties of one object to another: This is my code:

// Get type and create first object
Type itemType = Type.GetType(itemTypeName);
var item = Activator.CreateInstance(itemType);

// Set item properties
.. Code removed for clarity ..

// Get item from Entity Framework DbContext
var set = dataContext.Set(itemType);
var itemInDatabase = set.Find(id);
if (itemInDatabase == null)
{
    itemInDatabase = Activator.CreateInstance(itemType);
    set.Add(itemInDatabase);
}

// Copy item to itemInDatabase
Mapper.CreateMap(itemType, itemType);
Mapper.Map(item, itemInDatabase);

// Save changes
dataContext.SaveChanges();

问题是 Mapper.Map（）抛出 AutoMapperMappingException ：

Missing type map configuration or unsupported mapping.

Mapping types:
Object -> MachineDataModel
System.Object -> MyProject.DataModels.MachineDataModel

Destination path:
MachineDataModel

Source value:
MyProject.DataModels.MachineDataModel

我不太清楚问题是什么，该怎么解决？

I don't really understand what the problem is, and what can I do to fix it?

推荐答案

您需要使用 Map 的非通用重载：

You need to use the non-generic overload of Map:

Mapper.Map(item, itemInDatabase, item.GetType(), itemInDatabase.GetType());

原因是您当前使用的通用版本未使用实例的运行时类型你过关了。而是使用编译时间类型- item 的编译时间类型为 object ，因为这是 Activator.CreateInstance 。

The reason is that the generic version you are currently using doesn't use the runtime type of the instances you pass. Rather it uses the compile time type - and the compile time type of item is object because that's the return value of Activator.CreateInstance.

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