Deep copy vs. Shallow copy vs. Direct assignment

Depending on the settings specified, the mapping behavior may differ.

var src = new Source { AProperty A {get; set;} , BProperty B {get; set;} } 
var dest = src.Adapt<Destination>();

Deep copy

// Deep copy - default behavior
    var dest = new Destination { A = new AProperty{ int X = src.A.X }, B = new BProperty { int X = src.B.X} }

Shallow copy

Note

1. Changes mapping behavior only for member(property,field) source and destination type in registered custom mapping configuration.
2. Disable when destination member(property,field) using UseDestinationValue setting.
3. Disable when registered custom mapping configuration .NewConfig() for Type member(property,field).

//Shallow copy 
TypeAdapterConfig<Source, Destination>
    .NewConfig()
    .ShallowCopyForSameType(true);

    var dest = new Destination { A = src.A, B = src.B }

Direct assignment [v10.0.8+]

Note

1. Changes mapping behavior for Type.
2. Disable when destination member(property,field) using UseDestinationValue setting.
3. Disable when registered custom mapping configuration .NewConfig() contains the .MapWith() and/or MapToTargetWith() setting.

// DirectAssignment
TypeAdapterConfig<AProperty, AProperty>
    .NewConfig()
    .DirectAssignmentForSameType(true);

    var dest = new Destination { A = src.A, B = new BProperty { int X = src.B.X} }

    //for mapping AProperty to AProperty
        var a = new AProperty();
        var result =  a.Adapt<AProperty>(); 

        // behavior equal
        var result = a;

Copy vs. Merge

By default, Mapster will map all properties, even source properties containing null values. You can copy only properties that have values (merge) by using IgnoreNullValues method.

TypeAdapterConfig<TSource, TDestination>
    .NewConfig()
    .IgnoreNullValues(true);