使用AutoMapper映射字典 [英] Mapping dictionaries with AutoMapper

问题描述

鉴于这些类，我该如何映射它们的字典?

Given this these classes, how can I map a dictionary of them?

public class TestClass
{
    public string Name { get; set; }
}

public class TestClassDto
{
    public string Name { get; set; }
}


Mapper.CreateMap<TestClass, TestClassDto>();
Mapper.CreateMap<Dictionary<string, TestClass>, 
                  Dictionary<string, TestClassDto>>();

var testDict = new Dictionary<string, TestClass>();
var testValue = new TestClass() {Name = "value1"};
testDict.Add("key1", testValue);

var mappedValue = Mapper.Map<TestClass, TestClassDto>(testValue);

var mappedDict = Mapper.Map<Dictionary<string, TestClass>, 
                            Dictionary<string, TestClassDto>>(testDict);

映射其中一个，在这种情况下，mappedValue可以正常工作.

Mapping one of them, mappedValue in this case, works fine.

映射它们的字典最终在目标对象中没有任何条目.

Mapping a dictionary of them ends up with no entries in the destination object.

我在做什么?

推荐答案

您遇到的问题是因为AutoMapper难以映射词典的内容.您必须考虑它的存储-在这种情况下为 KeyValuePairs .

The problem you are having is because AutoMapper is struggling to map the contents of the Dictionary. You have to think what it is a store of - in this case KeyValuePairs.

如果您尝试为KeyValuePair组合创建一个映射器，您会很快发现您不能直接创建，因为 Key属性没有设置器.

If you try create a mapper for the KeyValuePair combination you will quickly work out that you can't directly as the Key property doesn't have a setter.

AutoMapper通过允许您使用构造函数进行映射来解决此问题.

AutoMapper gets around this though by allowing you to Map using the constructor.

/* Create the map for the base object - be explicit for good readability */
Mapper.CreateMap<TestClass, TestClassDto>()
      .ForMember( x => x.Name, o => o.MapFrom( y => y.Name ) );

/* Create the map using construct using rather than ForMember */
Mapper.CreateMap<KeyValuePair<string, TestClass>, KeyValuePair<string, TestClassDto>>()
      .ConstructUsing( x => new KeyValuePair<string, TestClassDto>( x.Key, 
                                                                    x.Value.MapTo<TestClassDto>() ) );

var testDict = new Dictionary<string, TestClass>();
var testValue = new TestClass()
{
    Name = "value1"
};
testDict.Add( "key1", testValue );

/* Mapped Dict will have your new KeyValuePair in there */
var mappedDict = Mapper.Map<Dictionary<string, TestClass>,
Dictionary<string, TestClassDto>>( testDict );

这篇关于使用AutoMapper映射字典的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！