如果object为null，如何配置Automapper 9以忽略Object-Properties，如果不为null，则如何映射 [英] How to configure Automapper 9 to ignore Object-Properties if object is null but map if not null

问题描述

我已经尝试了很多，但是找不到我真正想要的东西.这是我的情况:我有一个带有导航属性和viewModel的EF-Core实体:

I´ve tried a lot, but I can´t find what I´m really looking for. This is my case: I have an EF-Core entity with navigation-properties and a viewModel:

public class SomeEntity
{
    public Guid Id { get; set; }
    public virtual NestedObject NestedObject { get; set; }
    public DateTime Created { get; set; }
    public DateTime Modified { get; set; }
}

public class SomeEntityViewModel
{
    public Guid Id { get; set; }
    public string NestedObjectStringValue { get; set; }
    public int NestedValueIntValue { get; set; }
}

这是我的CreateMap，即使没有设置NestedObject-Property，它也会创建一个新的NestedObject(条件似乎在这里并不适用):

This is my CreateMap which creates a new NestedObject even if no NestedObject-Property is set (Condition doesn´t seem to apply here):

CreateMap<SomeEntityViewModel, SomeEntity>(MemberList.Source)
        .ForPath(m => m.NestedObject.StringValue, opt =>
        {
            opt.Condition(s => s.Destination.NestedObject != null); 
            opt.MapFrom(m => m.NestedObjectStringValue);
        });

这避免了在属性为null的情况下避免创建新的NestedObject，但如果不为null，则不会映射NestedObject属性:

This avoids Creating a new NestedObject if Properties are null but if not, the NestedObject Properties are not mapped:

CreateMap<SomeEntityViewModel, SomeEntity>(MemberList.Source)
    .ForMember(m => m.NestedObject, opt => opt.AllowNull());

第二个CreateMap如果设置了NestedObject-Properties，则不映射.如果未设置属性"，则首先创建一个新的NestedObject.但是两者都不起作用.有什么想法可以解决这个问题吗?

Second CreateMap doesn´t Map NestedObject-Properties if they are set, first creates a new NestedObject if the Properties are not set. But both together are not working. Any ideas how to solve this?

推荐答案

删除 ReverseMap()，然后尝试使用AutoMapper

Remove ReverseMap() ,then try to use AutoMapper Conditional Mapping and use ForPath instead of ForMember for nested child object properties:

CreateMap<SomeEntityViewModel, SomeEntity>()
    .ForPath(
            m => m.NestedObject.StringValue, 
            opt => {                         
                     opt.Condition(
                        s => s.DestinationMember != null && s.DestinationMember != "" 
                     );
                     opt.MapFrom(s => s.NestedObjectStringValue);
                   }
            );

与 IntValue 相同.

更新

因此，如果 NestedObject 为null，则您不想将 SomeEntityViewModel 中的值映射到它.如果 NestedObject 不为null，则映射有效.

So, if the NestedObject is null, you do not want to to map the value from SomeEntityViewModel to it. If the NestedObject is not null,mapping works.

请参考以下使用 AfterMap

CreateMap<SomeEntityViewModel, SomeEntity>()
             .ForMember(q => q.NestedObject, option => option.Ignore())
             .AfterMap((src, dst) => {
                     if(dst.NestedObject != null)
                     {
                     dst.NestedObject.StringValue = src.NestedObjectStringValue;
                     }

                 });

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