Automapper fails when mapping destination class has more properties

Question

I am using latest AutoMapper.Extensions.Microsoft.DependencyInjection 6.1.0. I have two classes

public class ConversionRate
    {
        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public long Id { get; set; }

        [Required]
        public string FromCurrency { get; set; }

        [Required]
        public string ToCurrency { get; set; }

        [Required]
        [Range(0, 100000)]
        public double Value { get; set; }

        [Required]
        public DateTime Date { get; set; }

        [ForeignKey("ProviderId")]
        public Provider Provider { get; set; }
        public int ProviderId { get; set; }
    }

and

public class RateDto
    {
        public DateTime Date { get; set; }
        public double Value { get; set; }
    }

this is the automapper profile

public class ConversionRateProfile : Profile
    {
        public ConversionRateProfile()
        {
            CreateMap<ConversionRate, RateDto>();
            CreateMap<RateDto, ConversionRate>();

        }
    }

and I get an error that there are unmapped properties

Unmapped properties:
Id
FromCurrency
ToCurrency
Provider
ProviderId

I was under the impression that automapper simply ignores the properties that exist in destination but not in source. What is the problem here?

In automapper you can set a property to be ignored when copying. This might be what you are looking for https://stackoverflow.com/questions/4987872/ignore-mapping-one-property-with-automapper — Alex Leo, May 16 '19 at 07:06

score 4 · Accepted Answer · answered May 16 '19 at 08:40

You can specify a MemberList enum value to the CreateMap method which configures whether to validate the source, destination, or none of the properties of the type are validated after mapping. In your case you should specify MemberList.Source from the RateDto to the ConverionRate types so only the mapping of properties on the source type (RateDto) are validated. The mapping from ConversionRate to RateDto should use MemberList.Destination to make sure all the properties in RateDto are mapped from ConversionRate. MemberList.Destination is the default value, so you don't have to explicitly specify it in the mapping profile.

You can configure the configuration validation in your mapping profile like this:

public ConversionRateProfile()
{
    CreateMap<ConversionRate, RateDto>();
    CreateMap<RateDto, ConversionRate>(MemberList.Source);
}

Automapper fails when mapping destination class has more properties

1 Answers1