##Mapster - The Mapper of Your Domain
var result = TypeAdapter.Adapt<NewType>(original);
or with extensions
var result = original.Adapt<NewType>();
PM> Install-Package Mapster
###Mapster 2.0 Released! Mapster 2.0 is now blistering fast! We upgraded the whole compilation unit while maintaining all functionality. The benchmarks:
Engine | Structs | Simple objects | Parent-Child | Parent-Children | Complex objects | Advance mapping |
---|---|---|---|---|---|---|
AutoMapper | 10871 | 27075 | 20895 | 19199 | 19333 | 21496 |
ExpressMapper | 690 | 1350 | 1195 | 1678 | 3130 | 3920 |
OoMapper | - | 2043 | 1277 | 1416 | 2777 | - |
ValueInjector | 8534 | 21089 | 17008 | 12355 | 16876 | 19970 |
TinyMapper | - | 1282 | - | - | - | - |
Mapster | - | 2382 | 1892 | 1626 | 4287 | 6756 |
Mapster 2.0 | 515 | 1251 | 950 | 1037 | 2455 | 2342 |
Native | 458 | 790 | 870 | 1253 | 3037 | 2754 |
(NOTE: Benchmark runner is from ExpressMapper. Benchmark was run against largest set of data, times are in milliseconds, lower is better. Blank values mean the library did not the test.)
###New Features
- Projection is improved to generate better sql queries
- Mapster is now able to map structs
- Flagged enums are supported
- Setting is now much more flexible
- You can now both opt-in and opt-out of settings
- Settings inheritance is able to inherit from interfaces
- Settings inheritance is now combined (it does not only pick from the closest parent)
- New rule based settings, you can defined your settings at a more granular level
- Settings are no longer only static, you can use different setting configurations for particular mappings
- You can ignore properties by attributes
- Now you can set up mapping between different types. Ex:
config.Map(dest => dest.AgeString, src => src.AgeInt)
- Mapster now supports circular reference mapping!
- Supports more frameworks (.NET 4.0, 4.5, .NET Core RC 5.4)
###Get started
- Ignore properties & attributes
- Property Mapping
- Merge Objects
- Shallow Copy
- Preserve reference (preventing circular reference stackoverflow)
####Mapping #####Mapping to a new object Mapster creates the destination object and maps values to it.
var destObject = TypeAdapter.Adapt<TSource, TDestination>(sourceObject);
or just
var destObject = TypeAdapter.Adapt<TDestination>(sourceObject);
or using extension methods
var destObject = sourceObject.Adapt<TDestination>();
#####Mapping to an existing object You make the object, Mapster maps to the object.
TDestination destObject = new TDestination();
destObject = TypeAdapter.Adapt(sourceObject, destObject);
or using extension methods
TDestination destObject = new TDestination();
destObject = sourceObject.Adapt(destObject);
#####Queryable Extensions Mapster also provides extensions to map queryables.
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();
}
#####Mapper Instance 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 adapter = new Adapter();
And usage is the same as with the static methods.
var result = adapter.Adapt<TDestination>(source);
####Conversion Mapster can map nearly all kind of objects. Here are some details.
#####Conversion of immutable types Converting between primitive types (ie. int, string, bool, double, decimal) is supported, including when those types are nullable. For all other types, if you can cast types in c#, you can also cast in Mapster.
var i = TypeAdapter.Adapt<string, int>("123"); //123
#####Conversion from/to enum
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 Mapster 2.0, flagged enums are also supported.
var e = TypeAdapter.Adapt<string, FileShare>("Read, Write, Delete");
//FileShare.Read | FileShare.Write | FileShare.Delete
#####Mapping POCO Mapster can map 2 different POCO types using the following rules
- Source and destination property names are the same. Ex:
dest.Name = src.Name
- Source has get method. Ex:
dest.Name = src.GetName()
- Source property has child object which can flatten to destination. Ex:
dest.ContactName = src.Contact.Name
ordest.Contact_Name = src.Contact.Name
In Mapster 2.0, POCO structs are also supported.
class Staff {
public string Name { get; set; }
public int GetAge() { return (DateTime.Now - this.BirthDate).TotalDays / 365.25; }
public Staff Supervisor { get; set; }
...
}
struct StaffDto {
public string Name { get; set; }
public int Age { get; set; }
public string SupervisorName { get; set; }
}
var dto = TypeAdapter.Adapt<Staff, StaffDto>(staff);
//dto.Name = staff.Name, dto.Age = staff.GetAge(), dto.SupervisorName = staff.Supervisor.Name
#####Mapping Lists This includes mapping among lists, arrays, collections, dictionary including various interfaces: IList, ICollection, IEnumerable etc...
var target = TypeAdapter.Adapt<List<Source>, IEnumerable<Destination>>(list);
####Setting
#####Setting per type
You can easily create settings for a type mapping by using: TypeAdapterConfig<TSource, TDestination>.NewConfig()
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.Ignore(dest => dest.Age)
.Map(dest => dest.FullName,
src => string.Format("{0} {1}", src.FirstName, src.LastName));
#####Global Settings Use global settings to apply policies to all mappings.
TypeAdapterConfig.GlobalSettings.Default.PreserveReference(true);
Then for individual type mappings, you can easily override the global setting(s).
TypeAdapterConfig<SimplePoco, SimpleDto>.NewConfig().PreserveReference(false);
#####Setting inheritance Type mappings will automatically inherit for source types. Ie. if you set up following config.
TypeAdapterConfig<SimplePoco, SimpleDto>.NewConfig()
.Map(dest => dest.Name, src => src.Name + "_Suffix");
A derived type of SimplePoco
will automatically apply the base mapping config.
var dest = TypeAdapter.Adapt<DerivedPoco, SimpleDto>(src); //dest.Name = src.Name + "_Suffix"
If you don't wish a derived type to use the base mapping, just define NoInherit
for that type.
TypeAdapterConfig<DerivedPoco, SimpleDto>.NewConfig().NoInherit(true);
//or at the global level
TypeAdapterConfig.GlobalSettings.Default.NoInherit(true);
And by default, Mapster will not inherit destination type mappings. You can turn on by AllowImplicitDestinationInheritance
.
TypeAdapterConfig.GlobalSettings.AllowImplicitDestinationInheritance = true;
Finally, Mapster also provides methods to inherit explicitly.
TypeAdapterConfig<DerivedPoco, DerivedDto>.NewConfig()
.Inherits<SimplePoco, SimpleDto>();
#####Rule based setting
To set the setting at a more granular level. You can use the When
method in global settings.
In the example below, when any source type and destination type are the same, we will not the copy the Id
property.
TypeAdapterConfig.GlobalSettings.When((srcType, destType, mapType) => srcType == destType)
.Ignore("Id");
In this example, the config would only apply to Query Expressions (projections).
TypeAdapterConfig.GlobalSettings.When((srcType, destType, mapType) => mapType == MapType.Projection)
.IgnoreAttribute(typeof(NotMapAttribute));
#####Overload setting You may wish to have different settings in different scenarios. If you would not like to apply setting at a static level, Mapster also provides setting instance configurations.
var config = new TypeAdapterConfig();
config.Default.Ignore("Id");
For type mappings, you can use the ForType
method.
config.ForType<TSource, TDestination>()
.Map(dest => dest.FullName,
src => string.Format("{0} {1}", src.FirstName, src.LastName));
You can apply a specific config instance by passing it to the Adapt
method. (NOTE: please reuse your config instance to prevent recompilation)
var result = TypeAdapter.Adapt<TDestination>(src, config);
Or to an Adapter instance.
var adapter = new Adapter(config);
var result = adapter.Adapt<TDestination>(src);
####Basic Customization When the default convention mappings aren't enough to do the job, you can specify complex source mappings.
#####Ignore Members & Attributes
Mapster will automatically map properties with the same names. You can ignore members by using the Ignore
method.
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.Ignore(dest => dest.Id);
You can ignore members annotated with specific attributes by using the IgnoreAttribute
method.
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.IgnoreAttribute(typeof(JsonIgnoreAttribute));
#####Property mapping You can customize how Mapster maps values to a property.
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.Map(dest => dest.FullName,
src => string.Format("{0} {1}", src.FirstName, src.LastName));
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()
.Map(dest => dest.FullName, src => src.FullName, srcCond => srcCond.City == "Victoria");
In Mapster 2.0, 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"
#####Merge object
By default, Mapster will map all properties, even source properties containing null values.
You can copy only properties that have values by using IgnoreNullValues
method.
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.IgnoreNullValues(true);
#####Shallow copy
By default, Mapster will recursively map nested objects. You can do shallow copying by setting ShallowCopyForSameType
to true
.
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.ShallowCopyForSameType(true);
#####Preserve reference (preventing circular reference stackoverflow)
When mapping objects with circular references, a stackoverflow exception will result.
This is because Mapster will get stuck in a loop tring to recursively map the circular reference.
If you would like to map circular references or preserve references (such as 2 properties pointing to the same object), you can do it by setting PreserveReference
to true
TypeAdapterConfig<TSource, TDestination>
.NewConfig()
.PreserveReference(true);
####Advance Customization
#####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(src => new TDestination(src.Id, src.Name));
//Example using an object initializer
TypeAdapterConfig<TSource, TDestination>.NewConfig()
.ConstructUsing(src => new TDestination{Unmapped = "unmapped"});
#####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.
//Global
TypeAdapterConfig.GlobalSettings.Default.AddDestinationTransforms((string x) => x.Trim());
//Per mapping configuration
TypeAdapterConfig<TSource, TDestination>.NewConfig()
.AddDestinationTransforms((string x) => x.Trim());
#####Custom Type Resolvers
In some cases, you may want to have complete control over how an object is mapped. You can register specific transformations using the MapWith
method.
//Example of transforming string to char[].
TypeAdapterConfig<string, char[]>.NewConfig()
.MapWith(str => str.ToCharArray());
####Validation To validate your mapping in unit tests and in order to help with "Fail Fast" situations, the following strict mapping modes have been added.
#####Explicit Mapping 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();
#####Checking Destination Member Forcing all destination properties to have a corresponding source member or explicit mapping/ignore:
//Default is "false"
TypeAdapterConfig.GlobalSettings.RequireDestinationMemberSource = true;
#####Validating Mappings Both a specific TypeAdapterConfig<Source, Destination> or all current configurations can be validated. 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.Compile();
//Validate globally
TypeAdapterConfig<Source, Destination>.NewConfig();
TypeAdapterConfig<Source2, Destination2>.NewConfig();
TypeAdapterConfig.GlobalSettings.Compile();