如何使用自动映射器映射对象，但目标对象根据配置看起来不同？

Question

I'm convinced there is a simple solution for my problem but I'm not seeing it, so I need some help in lighting me the way.

We use automapper to map our internal objects into fhir objects to communicate with different systems. Now one of the systems has been extended so that it needs the same fhir object but slightly different in the content. That means if our system is configured to use the old version, the fhir object has to look like as before. If the system has been configured to support the new version, the fhir object has to be filled with other content to meet the new system requirements.

In the profile class it is not possible to work with external configuration, so filling the object depending on my system configuration is not possbile there (as fas as I know). The objects to map have not changed, only the content has, so adding different maps to the automapper configuration won't work as the implementations do not differ for automapper. I tried Before- and AfterMapping-action but run into errors saying maps are missing. So what's the best way to achive this?

Answer 1

Let's assume you would use IConfiguration to detect which version your system is configured to use.

You can pass this information into the ResolutionContext that you can access it in your mapper configuration.

public class Service
{
    private readonly IConfiguration configuration;
    private readonly IMapper mapper;

    public Service(IConfiguration configuration, IMapper mapper)
    {
        this.configuration = configuration;
        this.mapper = mapper;
    }

    public DoSomething()
    {
        SourceClass source = new();

        DestinationClass destination = mapper.Map<DestinationClass>(
            source,
            // Here we pass the info whether to use the old or the new version.
            options =>
            options.Items["UseNewVersion"] =
                configuration.GetValue<bool>("UseNewVersion")
        );
    }
}

public class AutoMapperProfile : Profile
{
    public AutoMapperProfile()
    {
        CreateMap<SourceClass, DestinationClass>()
            .ForMember(
                destination => destination.Property,
                (source, destination, destinationMember, context) =>
                {
                    // Here we get whether to use the old or the new version.
                    bool useNewVersion = (bool)context.Items["UseNewVersion"];

                    return useNewVersion ? "NEW" : "OLD";
                }
            );
    }
}

Both of the Items properties are of type Dictionary<string, object> .

• IMappingOperationOptions.Items
• ResolutionContext.Items