Custom mapping

Custom member mapping

You can customize how Mapster maps values to a property.

TypeAdapterConfig<TSource, TDestination>
    .NewConfig()
    .Map(dest => dest.FullName,
        src => $"{src.FirstName} {src.LastName}");

You can even map when source and destination property types are different.

TypeAdapterConfig<TSource, TDestination>
    .NewConfig()
    .Map(dest => dest.Gender,      //Genders.Male or Genders.Female
        src => src.GenderString); //"Male" or "Female"

Mapping with condition

The Map configuration can accept a third parameter that provides a condition based on the source. If the condition is not met, Mapster will retry with next conditions. Default condition should be added at the end without specifying condition. If you do not specify default condition, null or default value will be assigned.

TypeAdapterConfig<TSource, TDestination>
    .NewConfig()
    .Map(dest => dest.FullName, src => "Sig. " + src.FullName, srcCond => srcCond.Country == "Italy")
    .Map(dest => dest.FullName, src => "Sr. " + src.FullName, srcCond => srcCond.Country == "Spain")
    .Map(dest => dest.FullName, src => "Mr. " + src.FullName);

NOTE: if you would like to skip mapping, when condition is met, you can use IgnoreIf (https://github.com/MapsterMapper/Mapster/wiki/Ignoring-members#ignore-conditionally).

Mapping to non-public members

Map command can map to private member by specify name of the members.

TypeAdapterConfig<TSource, TDestination>
    .NewConfig()
    .Map("PrivateDestName", "PrivateSrcName");

For more information about mapping non-public members, please see https://github.com/MapsterMapper/Mapster/wiki/Mapping-non-public-members.

Deep destination property

Map can be defined to map deep destination property.

TypeAdapterConfig<Poco, Dto>.NewConfig()
    .Map(dest => dest.Child.Name, src => src.Name);

Null propagation

If Map contains only property path, null propagation will be applied.

TypeAdapterConfig<Poco, Dto>.NewConfig()
    .Map(dest => dest.Name, src => src.Child.Name);

From above example, if src.Child is null, mapping will return null instead of throw NullPointerException.

Multiple sources

Example 1: Include property to Poco

public class SubDto
{
    public string Extra { get; set; }
}
public class Dto
{
    public string Name { get; set; }
    public SubDto SubDto { get; set; }
}
public class Poco
{
    public string Name { get; set; }
    public string Extra { get; set; }
}

In this case, you would like to map all properties from Dto to Poco, and also include all properties from Dto.SubDto to Poco. You can do this by just mapping dto.SubDto to poco in configuration.

TypeAdapterConfig<Dto, Poco>.NewConfig()
    .Map(poco => poco, dto => dto.SubDto);

Example 2: Mapping 2 objects to poco

In this example, you have Dto1 and Dto2, and you would like to map both objects to a Poco. You can do this by wrapping Dto1 and Dto2 into a tuple. And then mapping tuple.Item1 and tuple.Item2 to Poco.

TypeAdapterConfig<(Dto1, Dto2), Poco>.NewConfig()
    .Map(dest => dest, src => src.Item1)
    .Map(dest => dest, src => src.Item2);