Automapper: Ignore on condition of

问题

Is it possible to ignore mapping a member depending on the value of a source property?

For example if we have:

public class Car
{
    public int Id { get; set; }
    public string Code { get; set; }
}

public class CarViewModel
{
    public int Id { get; set; }
    public string Code { get; set; }
}

I'm looking for something like

Mapper.CreateMap<CarViewModel, Car>()
      .ForMember(dest => dest.Code, 
      opt => opt.Ignore().If(source => source.Id == 0))

So far the only solution I have is too use two different view models and create different mappings for each one.

回答1:

The Ignore() feature is strictly for members you never map, as these members are also skipped in configuration validation. I checked a couple of options, but it doesn't look like things like a custom value resolver will do the trick.

Use the Condition() feature to map the member when the condition is true:

Mapper.CreateMap<CarViewModel, Car>()
 .ForMember(dest => dest.Code, opt => opt.Condition(source => source.Id != 0))

回答2:

I ran into a similar issue, and while this will overwrite the existing value for dest.Code with null, it might be helpful as a starting point:

AutoMapper.Mapper.CreateMap().ForMember(dest => dest.Code,config => config.MapFrom(source => source.Id != 0 ? null : source.Code));

回答3:

Here is the documentation of the conditional mapping: http://docs.automapper.org/en/latest/Conditional-mapping.html

There's also another method called PreCondition very useful on certain scenarios since it runs before the source value is resolved in the mapping process:

Mapper.PreCondition<CarViewModel, Car>()
 .ForMember(dest => dest.Code, opt => opt.Condition(source => source.Id == 0))

来源：https://stackoverflow.com/questions/2451189/automapper-ignore-on-condition-of

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automapper