##Mapster - The Mapper of Your Domain

What was Fpr has been mapped to Mapster! Had to grow up (a little).
var newThing = TypeAdapter.Adapt<Fpr, Mapster>(oldThing);

But still a fast, fun and stimulating object to object mapper for .Net 4.5.

Mapster was originally forked from FastMapper (https://fmapper.codeplex.com/). Mapster maps properties by convention, including nested complex objects and collections, but also supports explicit mapping.

This fork fixes some issues and includes some additions to make the mapper more configurable and useful for .Net 4.5:

• Support for IReadOnlyList
• Mapping of members with non-public setters
• Automatic mapping of nullable primitives to non-nullable primitives
• Improved error messages that help you find configuration errors
• Conditional mapping
• Assembly scanning for custom mappers
• Strict modes to err if types or members are not explicity mapped (implicit/forgiving mapping is the default).
• Type specific destination transforms (typically such as trim or lowercase all strings). Can be used on any destination type.
• Custom destination creation (not just default constructor)
• Automatic Enum <=> String mapping
• Mapper instance creation for injection situations
• Lots more stuff below...

###Examples ####Mapping to a new object Mapster makes the object and maps values to it.

TDestination destObject = TypeAdapter.Adapt<TSource, TDestination>(sourceObject);

####Mapping to an existing object You make the object, Mapster maps to the object.

TDestination destObject = new TDestination();
destObject = TypeAdapter.Adapt(sourceObject, destObject);

####Mapping Lists Included This includes lists, arrays, collections, enumerables etc...

var destObjectList = TypeAdapter.Adapt<List<TSource>, List<TDestination>>(sourceList);

####Mapping Enums Included Mapster maps enums to numerics automatically, but it also maps strings to and from enums automatically in a fast manner.
The default Enum.ToString() in .Net is quite slow. The implementation in Mapster is double the speed.
Likewise, a fast conversion from strings to enums is also included. If the string is null or empty, the enum will initialize to the first enum value.

In addition, fast Enum mapper extension methods are included for convenience.

//Convert enum to string
var myEnum = new SomeEnum.FirstValue;
myEnum.ToFastString();

//Convert string to enum
var myEnumString = "FirstValue";
myEnumString.ToFastEnum<SomeEnum>();

####Customized Mapping When the default convention mappings aren't enough to do the job, you can specify complex source mappings.

TypeAdapterConfig<TSource, TDestination>()
.NewConfig()
.IgnoreMember(dest => dest.Property)
.Map(dest => dest.FullName, 
         src => string.Format("{0} {1}", src.FirstName, src.LastName));

####Implicit TSource Mapping Inheritance If a mapping configuration doesn't exist for a source ==> destination type, but a mapper does exist for a base source type to the destination, that mapping will be used. This allows mappings for less derived source types to be used to satisfy multiple derived mappings. FPR will search downward the source class hierarchy until it finds a matching configuration.
If no match exists, it will create a default configuration (the same behavior if no mapping was present). It doesn't combine derived configs, it will stop at the first match.
For example, if you have:

public class SimplePoco
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

public class DerivedPoco : SimplePoco
{...}

public class DerivedPoco2 : SimplePoco
{...}

public class SimpleDto
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

The following mapping will be used when mapping the SimplePoco or either of the derived POCOs to the Simple DTO.

TypeAdapterConfig<SimplePoco, SimpleDto>.NewConfig()
    .Map(dest => dest.Name, src => src.Name + "_Suffix");

If you don't wish a derived type to use the base mapping, just define a new configuration for that type.

TypeAdapterConfig<DerivedPoco2, SimpleDto>.NewConfig();

####Implicit TSource and TDestination Mapping Inheritance In some cases you may wish to derive a mapping based on both the source and destination types. In such a case, setting the global configuration AllowImplicitDestinationInheritance setting to true will allow inheritance of a mapping based on both the source and destination types. The source class hierarchy is traversed in an inside loop and the destination class hierarchy is traversed in an outside loop until a match is found.

public class SimplePoco
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

public class DerivedPoco : SimplePoco
{...}

public class SimpleDto
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

public class DerivedDto : DerivedDto
{...}

The following mapping will be used for any permutation of Simple/Derived Poco to Simple/Derived Dto unless overridden by a specific configuration.

TypeAdapterConfig.GlobalSettings.AllowImplicitDestinationInheritance = true;
TypeAdapterConfig<SimplePoco, SimpleDto>.NewConfig()
    .Map(dest => dest.Name, src => src.Name + "_Suffix");

If you don't wish a specific permutation to use the base mapping, just define a new configuration for that permutation.

TypeAdapterConfig<DerivedPoco, SimpleDto>.NewConfig();

In some cases, you may wish to have one mapping inherit from another mapping. In this case, anything set on the derived mapping will override settings on the base mapping. So unlike implicit mapping inheritance, where the goal is to find an applicable mapping configuration and configurations are not combined, with Explicit Inheritance, each derived mapping overrides the settings of the inherited mapping. Use the Inherits<TBaseSource, TBaseDestination> configuration method to accomplish this where TBaseSource and TBaseDestination must be assignable from the derived configuration's TSource and TDestination respectively. For example, if you have:

public class SimplePoco
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

public class DerivedPoco : SimplePoco
{...}

public class SimpleDto
{
    public Guid Id { get; set; }
    public string Name { get; set; }
}

public class DerivedDto : SimpleDto
{...}

And you have the following base mapping:

TypeAdapterConfig<SimplePoco, SimpleDto>.NewConfig()
    .Map(dest => dest.Name, src => src.Name + "_Suffix");

You can base the mapping of the derived classes on this base mapping:

TypeAdapterConfig<DerivedPoco, DerivedDto>.NewConfig()
    .Inherits<SimplePoco, SimpleDto>();

####Custom Destination Object Creation You can provide a function call to create your destination objects instead of using the default object creation (which expects an empty constructor). To do so, use the "ConstructUsing()" method when configuring. This method expects a function that will provide the destination instance. You can call your own constructor, a factory method, or anything else that provides an object of the expected type.

//Example using a non-default constructor
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .ConstructUsing(() => new TDestination("constructorValue"));

//Example using an object initializer
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .ConstructUsing(() => new TDestination{Unmapped = "unmapped"});

####Custom Type Resolvers In some cases, you may want to have complete control over how an object is mapped. In this case, you can register a custom type resolver. It's important to note that when using a custom type resolver, that all other mapping associated with the type is ignored. So all mapping must take place within the resolver. The custom type resolver must implement the ITypeResolver interface and register it using MapWith().

//Example using MapWith resolver generic call.
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .MapWith<TCustomTypeResolver>();

//Example using MapWith resolver factory function
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .MapWith(() => new TCustomTypeResolver());

//Example using MapWith resolver instance
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .MapWith(customResolverInstance);

####Custom Value Resolvers In some cases, you may want to encapsulate a value conversion into a separate class. In this case, you can use a custom value resolver by registering it using Resolve(). The value resolver must implement the IValueResolver interface.

//Example using MapWith resolver generic call.
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .Resolve<TCustomValueResolver, string>(dest => dest.Name);

//Example using value resolver factory function
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .Resolve(dest => dest.Name, () => new TCustomValueResolver());

//Example using value resolver instance
TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .Resolve(dest => dest.Name, customValueResolver);

####Type-Specific Destination Transforms This allows transforms for all items of a type, such as trimming all strings. But really any operation can be performed on the destination value before assignment. This can be set up at either a global or a mapping level.

//Global
TypeAdapterConfig.GlobalSettings.DestinationTransforms.Upsert<string>(x => x.Trim());

//Per mapping configuration
TypeAdapterConfig<TSource, TDestination>.NewConfig()
    .DestinationTransforms.Upsert<string>(x => x.Trim());

####Conditional Mapping The Map configuration can accept a third parameter that provides a condition based on the source. If the condition is not met, the mapping is skipped altogether.

TypeAdapterConfig<TSource, TDestination>()
    .NewConfig()
    .IgnoreMember(dest => dest.Property)
    .Map(dest => dest.FullName, src => src.FullName, srcCond => srcCond.City == "Victoria");

####Max Depth When mapping nested or tree-type structures, it's often necessary to specify a max nesting depth to prevent overflows.

TypeAdapterConfig<TSource, TDestination>
            .NewConfig()
            .MaxDepth(3);

####Queryable Extensions

using(MyDbContext context = new MyDbContext())
{
    // Build a Select Expression from DTO
    var destinations = context.Sources.Project().To<Destination>().ToList();

    // Versus creating by hand:
    var destinations = context.Sources.Select(c => new Destination(){
        Id = p.Id,
        Name = p.Name,
        Surname = p.Surname,
        ....
    })
    .ToList();
}

####Forcing Explicit Mapping In order to help with "Fail Fast" situations, the following strict mapping modes have been added. An ArgumentOutOfRange exception will currently be thrown in the situations below if an appropriate mapping and/or source cannot be located.

Forcing all destination properties to have a corresponding source member or explicit mapping/ignore:

//Default is "false"
TypeAdapterConfig.GlobalSettings.RequireDestinationMemberSource = true;

Forcing all classes to be explicitly mapped:

//Default is "false"
TypeAdapterConfig.GlobalSettings.RequireExplicitMapping = true;
//This means you have to have an explicit configuration for each class, even if it's just:
TypeAdapterConfig<Source, Destination>.NewConfig();

####Validating Mappings Both a specific TypeAdapterConfig<Source, Destination> or all current configurations can be validated. This will throw and ArgumentOutOfRangeException that contains all of the existing missing destination mappings. In addition, if Explicit Mappings (above) are enabled, it will also include errors for classes that are not registered at all with the mapper.

//Validate a specific config
var config = TypeAdapterConfig<Source, Destination>.NewConfig();
config.Validate();

//Validate globally
TypeAdapterConfig<Source, Destination>.NewConfig();
TypeAdapterConfig<Source2, Destination2>.NewConfig();
TypeAdapterConfig.Validate();

####Mapper Instance Creation In some cases, you need an instance of a mapper (or a factory function) to pass into a DI container. Mapster has the IAdapter and Adapter to fill this need:

IAdapter instance = TypeAdapter.GetInstance();

###Assembly Scanning for Custom Mappings To make it easier to register custom mappings, we've implemented an assembly scanning approach. To allow this, either inherit from IRegistry or Registry in the Mapster.Registration namespace.

Override the Apply() method and perform your registrations there. When your app starts up, use the Registrar class to perform registration.

//Implement a registry class
public class MyRegistry : Registry
{
    public override void Apply()
    {
        TypeAdapterConfig<TSource, TDestination>.NewConfig()
            .IgnoreMember(dest => dest.CurrencyCode)
            .IgnoreMember(dest => dest.ExtraElements);
    }
}

//In my boostrap/startup code, call the registry
//Method 1: Call registry directly with extension method
new MyRegistry().Register();

//Method 2: Scan the assembly (by assembly or class type)
Registrar.RegisterFromAssemblyContaining<MyRegistry>();
//or
Assembly.GetExecutingAssembly().RegisterFromAssembly();

###Performance Comparisons When aggregating times across complex and simple objects, we're seeing a ~30x speed improvement in comparison to AutoMapper, but it's obviously very dependent upon your situation.

####Benchmark "Complex" Object

The following test converts a Customer object with 2 nested address collections and two nested address sub-objects to a DTO.

Customer c = new Customer()
{
    Address = new Address() { City = "istanbul", Country = "turkey", Id = 1, Street = "istiklal cad." },
    HomeAddress = new Address() { City = "istanbul", Country = "turkey", Id = 2, Street = "istiklal cad." },
    Id = 1,
    Name = "Eduardo Najera",
    Credit = 234.7m,
    WorkAddresses = new List<Address>() { 
        new Address() { City = "istanbul", Country = "turkey", Id = 5, Street = "istiklal cad." },
        new Address() { City = "izmir", Country = "turkey", Id = 6, Street = "konak" }
    },
    Addresses = new List<Address>() { 
        new Address() { City = "istanbul", Country = "turkey", Id = 3, Street = "istiklal cad." },
        new Address() { City = "izmir", Country = "turkey", Id = 4, Street = "konak" }
    }.ToArray()
};

Competitors : Handwriting Mapper, Mapster, FastMapper, AutoMapper

Iterations : 100
Handwritten Mapper:     1
Mapster:                0
AutoMapper:             10

Iterations : 10000
Handwritten Mapper:     4
Mapster:                17
AutoMapper:             507

Iterations : 100000
Handwritten Mapper:     29
Mapster:                177
AutoMapper:             5058