Automapper:如何映射嵌套对象? [英] Automapper: how to map nested object?
问题描述
我正在使用Automapper语法. 我有一个PropertySurveys列表,每个列表包含1个Property. 我希望将集合中的每个项目映射到一个结合了2个类的新对象中.
I am struggling with the Automapper syntax. I have a List of PropertySurveys, each containing 1 Property. I wish to map each item on the collection into a new object which combines the 2 classes.
所以我的代码如下;
var propertySurveys = new List<PropertyToSurveyOutput >();
foreach (var item in items)
{
Mapper.CreateMap<Property, PropertyToSurveyOutput >();
var property = Mapper.Map<PropertyToSurvey>(item.Property);
Mapper.CreateMap<PropertySurvey, PropertyToSurveyOutput >();
property = Mapper.Map<PropertyToSurvey>(item);
propertySurveys.Add(property);
}
我的简化类如下;
public class Property
{
public string PropertyName { get; set; }
}
public class PropertySurvey
{
public string PropertySurveyName { get; set; }
public Property Property { get; set;}
}
public class PropertyToSurveyOutput
{
public string PropertyName { get; set; }
public string PropertySurveyName { get; set; }
}
因此在PropertyToSurveyOutput对象中,设置了第一个映射PropertyName之后.然后,在设置第二个映射PropertySurveyName之后,但是PropertyName被覆盖为null. 我该如何解决?
So in the PropertyToSurveyOutput object, after the first mapping PropertyName is set. Then after the second mapping PropertySurveyName is set, but PropertyName is overridden to null. How do I fix this?
推荐答案
首先,Automapper支持集合映射.您无需将每个项目都映射成一个循环.
First of all, Automapper supports mapping of collections. You don't need to map each item in a loop.
第二个-您不必每次都需要映射单个对象时重新创建地图.将映射创建放入应用程序的开始代码中(或在第一次使用映射之前).
Second - you don't need to re-create map each time you need to map single object. Put mappings creation to application start code (or before first usage of mapping).
最后-使用Automapper,您可以创建映射并定义如何对某些属性进行自定义映射:
And last - with Automapper you can create mapping and define how to do custom map for some properties:
Mapper.CreateMap<PropertySurvey, PropertyToSurveyOutput>()
.ForMember(pts => pts.PropertyName, opt => opt.MapFrom(ps => ps.Property.PropertyName));
用法:
var items = new List<PropertySurvey>
{
new PropertySurvey {
PropertySurveyName = "Foo",
Property = new Property { PropertyName = "X" } },
new PropertySurvey {
PropertySurveyName = "Bar",
Property = new Property { PropertyName = "Y" } }
};
var propertySurveys = Mapper.Map<List<PropertyToSurveyOutput>>(items);
结果:
[
{
"PropertyName": "X",
"PropertySurveyName": "Foo"
},
{
"PropertyName": "Y",
"PropertySurveyName": "Bar"
}
]
更新:如果您的Property
类具有许多属性,则可以定义两个默认映射-一个来自Property
的映射:
UPDATE: If your Property
class has many properties, you can define two default mappings - one from Property
:
Mapper.CreateMap<Property, PropertyToSurveyOutput>();
和PropertySurvey
中的一个.在PropertySurvey
中使用映射后,请使用第一个映射:
And one from PropertySurvey
. And use first mapping after you used mapping from PropertySurvey
:
Mapper.CreateMap<PropertySurvey, PropertyToSurveyOutput>()
.AfterMap((ps, pst) => Mapper.Map(ps.Property, pst));
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