Two ways

2-ways mapping

If you need to map object from POCO to DTO, and map back from DTO to POCO. You can define the setting once by using TwoWays.

TypeAdapterConfig<Poco, Dto>
    .NewConfig()
    .TwoWays()
    .Map(dto => dto.Code, poco => poco.Id); //<-- this setting will apply dto.Code = poco.Id & poco.Id = dto.Code for reverse mapping

NOTE: TwoWays command need to call before setting to take effect.

TypeAdapterConfig<Poco, Dto>
    .NewConfig()
    .Map(dto => dto.Foo, poco => poco.Bar)  //<-- this map only apply to Poco->Dto
    .TwoWays()
    .Map(dto => dto.Foz, poco => poco.Baz); //<-- this map will apply both side

Unflattening

By default, Mapster will perform flattening.

class Staff {
    public string Name { get; set; }
    public Staff Supervisor { get; set; }
    ...
}

struct StaffDto {
    public string SupervisorName { get; set; }
}

Above example, without any setup, you can map from POCO to DTO and you will get SupervisorName from Supervisor.Name (flattening).

However, unflattening process needed to be defined. You can map to Supervisor.Name from SupervisorName by

using Unflattening.

TypeAdapterConfig<StaffDto, Staff>.NewConfig()
    .Unflattening(true);

using TwoWays

TypeAdapterConfig<Staff, StaffDto>
    .NewConfig()
    .TwoWays(); //<-- this will also map poco.Supervisor.Name = dto.SupervisorName for reverse mapping