我们如何在自动映射器中为同一实体创建不同的映射

Question

I need to write mapping for an entity to its DTO for listing purpose and details view of an entity. But for listing I need to ignore a list property because of DTO because I don't want to load it, I have enabled Lazy loading in Entity framework. How can I create two mappings of same entity or add ignore for a property while querying data for list view.

cfg.CreateMap<page, PageViewModel>().ForMember(t => t.PageRows, opts => opts.MapFrom(s => s.page_rows)).
            ForMember(t => t.PageRules, opts => opts.MapFrom(s => s.page_rules.Select(x => x.rule_id)));

---

cfg.CreateMap<page, PageViewModel>().ForMember(t => t.PageRows, opts => opts.Ignore()).
            ForMember(t => t.PageRules, opts => opts.MapFrom(s => s.page_rules.Select(x => x.rule_id)));

Answer 1

You can setup a Precondition with Func<ResolutionContext, bool> and then use the Map method overloads with Action<IMappingOperationOptions> to pass the controlling parameter through Items dictionary.

For instance:

.ForMember(t => t.PageRows, opts => 
{
     opts.MapFrom(s => s.page_rows);
     opts.PreCondition(context => !context.Items.ContainsKey("IgnorePageRows"));
})

and then:

IEnumerable<page> source = ...;
var withPageRows = Mapper.Map<List<PageViewModel>>(source);
var noPageRows = Mapper.Map<List<PageViewModel>>(source, 
    opts => opts.Items.Add("IgnorePageRows", null));

Reference: Conditional mapping

Answer 2

You would have to create two different DTO classes to map to. If you do not want to do that, you also have another option which would be to create two marker interfaces and map to those.