Conversions

Mapperly implements several types of automatic conversions (in order of priority):

Name	Description	Conditions
Direct assignment	Directly assigns the source object to the target	Source type is assignable to the target type and UseDeepCloning is false
Queryable	Projects the source queryable to the target queryable	Source and target types are IQueryable<>
Dictionary	Maps a source dictionary to an enumerable target	Source type is an IDictionary<,> or an IReadOnlyDictionary<,>
Enumerable	Maps an enumerable source to an enumerable target	Source type is an IEnumerable<>
Span	Maps a Span<>, ReadOnlySpan<> to or from Span<>, ReadOnlySpan<> or enumerable	Source or target type is a Span<>, ReadOnlySpan<>
Tuple	Create a new instance of a ValueTuple or tuple expression i.e. (10, 12)	Target type is a ValueTuple<> or tuple expression
Memory	Maps a Memory<>, ReadOnlyMemory<> to or from Memory<>, ReadOnlyMemory<>, Span<>, ReadOnlySpan<> or enumerable	Source or target type is a Memory<> or ReadOnlyMemory<>
Implicit cast	Implicit cast operator	An implicit cast operator is defined to cast from the source type to the target type
Parse method	Uses a static Parse method on the target type	Source type is a string and target has a static method with the following signature: TTarget Parse(string).
Constructor	Uses a constructor on the target type with the source as single parameter	Target type has a visible constructor with a single parameter of the source type.
String to enum	Maps a string to an enum member name	Source type is a string and the target type is an enum
Enum to string	Maps an enum member name to a string	Source type is an enum and the target type is a string
Enum to enum	Maps an enum to another enum either by value or by member name	Source and target types are enums
Explicit cast	Explicit cast operator	An explicit cast operator is defined to cast from the source type to the target type
ToString	ToString method of an object	Target type is a string
ToTarget	ToTTarget method of an object, excluded ToString	Source object contains method with signature TTarget ToTTarget()
DateTime to DateOnly	Maps a DateTime to a DateOnly	Source type is a DateTime and target type is a DateOnly
DateTime to TimeOnly	Maps a DateTime to a TimeOnly	Source type is a DateTime and target type is a TimeOnly
Static method	Convert source uses source type static ToTTarget method or target type static CreateFromTTarget, FromTSource, Create, CreateFrom, except for converting DateTime to DateOnly or TimeOnly	The source type contains a static method with signature TTarget ToTTarget() or the target type contains one of the following static methods TTarget Create(TSource), TTarget CreateFrom(TSource), TTarget CreateFromTTarget(TSource) TTarget FromTSource(TSource)
New instance	Create a new instance of the target type and map all properties	The target type has a visible constructor or an object factory exists for the target type

Note: To exclude a candidate conversion method (Parse, ToTarget instance methods, or static Create/CreateFrom/From/To methods), annotate that method with [MapperIgnore].

This only works when the annotated method is in the same assembly as the mapper unless Mapperly attributes are preserved at runtime; see the "Ignore a member at definition" section in the mapper configuration docs.

Disable all automatic conversions

To disable all conversions supported by Mapperly set EnabledConversions to None:

[Mapper(EnabledConversions = MappingConversionType.None)]
public partial class CarMapper
{
  ...
}

Disable specific automatic conversions

To disable a specific conversion type, set EnabledConversions to All excluding the conversion type to disable:

// this disables conversions using the ToString() method:
[Mapper(EnabledConversions = MappingConversionType.All & ~MappingConversionType.ToStringMethod)]
public partial class CarMapper
{
  ...
}

Enable only specific automatic conversions

To enable only specific conversion types, set EnabledConversions the conversion type to enable:

// This disables conversions using the ToString() method, which is enabled by default:
[Mapper(EnabledConversions = MappingConversionType.Constructor | MappingConversionType.ExplicitCast)]
public partial class CarMapper
{
  ...
}