How to configure Automapper 9 to ignore Object-Properties if object is null but map if not null

问题

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; }
}

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);
        });

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());

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?

回答1:

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);
                   }
            );

The same to IntValue.

Update

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.

Please refer to below code which uses AfterMap

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

                 });

来源：https://stackoverflow.com/questions/58354104/how-to-configure-automapper-9-to-ignore-object-properties-if-object-is-null-but