How to set up Automapper in ASP NET Core

Question

I m relatively new at  NET  and I decided to tackle  NET Core instead of learning the  old ways   I found a detailed article about setting up AutoMapper for  NET Core here  but is there a more simple walkthrough for a newbie

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In my Startup cs  Core 2 2  Automapper 8 1 1   services AddAutoMapper new Type     typeof DAL MapperProfile                    In my data access project  namespace DAL       public class MapperProfile   Profile                  place holder for AddAutoMapper  to bring in the DAL assembly            In my model definition  namespace DAL Models       public class PositionProfile   Profile               public PositionProfile                         CreateMap lt Position  PositionDto v1 gt                          public class Position

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I want to extend  theutz s answers - namely this line       services AddAutoMapper typeof Startup         lt -- newer automapper version uses this signature    There is a bug  probably  in AutoMapper Extensions Microsoft DependencyInjection version 3 2 0   I m using  NET Core 2 0   This is tackled in this GitHub issue  If your classes inheriting AutoMapper s Profile class exist outside of assembly where you Startup class is they will probably not be registered if your AutoMapper injection looks like this   services AddAutoMapper      unless you explicitly specify which assemblies to search AutoMapper profiles for   It can be done like this in your Startup ConfigureServices   services AddAutoMapper  lt assembies gt  or  lt type in assemblies gt      where  assemblies  and  type in assemblies  point to the assembly where Profile classes in your application are specified  E g   services AddAutoMapper typeof ProfileInOtherAssembly   typeof ProfileInYetAnotherAssembly      I suppose  and I put emphasis on this word  that due to following implementation of parameterless overload  source code from GitHub     public static IServiceCollection AddAutoMapper this IServiceCollection services         return services AddAutoMapper null  AppDomain CurrentDomain GetAssemblies         we rely on CLR having already JITed assembly containing AutoMapper profiles which might be or might not be true as they are only jitted when needed  more details in this StackOverflow question

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services AddAutoMapper    didn t work for me   I am using Asp Net Core 2 0   After configuring as below     var config   new AutoMapper MapperConfiguration cfg   gt                               cfg CreateMap lt ClientCustomer  Models Customer gt              initialize the mapper        IMapper mapper   config CreateMapper     and add the mapper object to services as a singleton  services AddSingleton mapper    this way I am able to add a DI to controller    private IMapper autoMapper   null     public VerifyController IMapper mapper                       autoMapper   mapper          and I have used as below in my action methods    ClientCustomer customerObj   autoMapper Map lt ClientCustomer gt  customer

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I figured it out  Here s the details   Add the main AutoMapper Package to your solution via NuGet   Add the AutoMapper Dependency Injection Package to your solution via NuGet   Create a new class for a mapping profile   I made a class in the main solution directory called MappingProfile cs and add the following code   I ll use a User and UserDto object as an example   public class MappingProfile   Profile        public MappingProfile                 Add as many of these lines as you need to map your objects          CreateMap lt User  UserDto gt              CreateMap lt UserDto  User gt                 Then add the AutoMapperConfiguration in the Startup cs as shown below   public void ConfigureServices IServiceCollection services                 Ignore code before this         Auto Mapper Configurations      var mapperConfig   new MapperConfiguration mc   gt                  mc AddProfile new MappingProfile                    IMapper mapper   mapperConfig CreateMapper         services AddSingleton mapper         services AddMvc          To invoke the mapped object in code  do something like the following   public class UserController   Controller            Create a field to store the mapper object      private readonly IMapper  mapper           Assign the object in the constructor for dependency injection      public UserController IMapper mapper              mapper   mapper               public async Task lt IActionResult gt  Edit string id                 Instantiate source object              Get it from the database or whatever your code calls for           var user   await  context Users               SingleOrDefaultAsync u   gt  u Id    id                Instantiate the mapped data transfer object             using the mapper you stored in the private field              The type of the source object is the first type argument             and the type of the destination is the second              Pass the source object you just instantiated above             as the argument to the  mapper Map lt  gt    method           var model    mapper Map lt UserDto gt  user                     Do whatever you want after that               I hope this helps someone starting fresh with ASP NET Core  I welcome any feedback or criticisms as I m still new to the  NET world

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For ASP NET Core  tested using 2 0  and 3 0   if you prefer to read the source documentation  https   github com AutoMapper AutoMapper Extensions Microsoft DependencyInjection blob master README md  Otherwise following these 4 steps works    Install AutoMapper Extensions Microsoft DependancyInjection from nuget  Simply add some profile classes   Then add below to your startup cs class  services AddAutoMapper OneOfYourProfileClassNamesHere  Then simply Inject IMapper in your controllers or wherever you need it    public class EmployeesController        private readonly IMapper  mapper       public EmployeesController IMapper mapper             mapper   mapper          And if you want to use ProjectTo its now simply   var customers   await dbContext Customers ProjectTo lt CustomerDto gt   mapper ConfigurationProvider  ToListAsync

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I like a lot of answers  particularly  saineshwar  s one  I m using  net Core 3 0 with AutoMapper 9 0  so I feel it s time to update its answer    What worked for me was in Startup ConfigureServices      register the service in this way        services AddAutoMapper cfg   gt  cfg AddProfile lt MappingProfile gt                                     AppDomain CurrentDomain GetAssemblies       I think that rest of  saineshwar answer keeps perfect  But if anyone is interested my controller code is     HttpGet   id     public async Task lt ActionResult gt  GetIic int id            context is a DB provider     var Iic   await  context Find id  ConfigureAwait false        if  Iic    null                return NotFound               var map    mapper Map lt IicVM gt  Iic        return Ok map       And my mapping class   public class MappingProfile   Profile       public MappingProfile                 CreateMap lt Iic  IicVM gt                 ForMember dest   gt  dest DepartmentName  o   gt  o MapFrom src   gt  src Department Name                ForMember dest   gt  dest PortfolioTypeName  o   gt  o MapFrom src   gt  src PortfolioType Name                   ReverseMap              ----- EDIT -----  After reading the docs linked in the comments by Lucian Bargaoanu  I think it s better to change this answer a bit    The parameterless services AddAutoMapper    that had the  saineshwar answer  doesn t work anymore  at least for me   But if you use the NuGet assembly AutoMapper Extensions Microsoft DependencyInjection  the framework is able to inspect all the classes that extend AutoMapper Profile  like mine  MappingProfile     So  in my case  where the class belong to the same executing assembly  the service registration can be shortened to services AddAutoMapper System Reflection Assembly GetExecutingAssembly      A more elegant approach could be a parameterless extension with this coding     Thanks  Lucian

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I am using AutoMapper 6 1 1 and asp net Core 1 1 2   First of all  define Profile classes inherited by Profile Class of Automapper  I Created IProfile interface which is empty  the purpose is only to find the classes of this type    public class UserProfile   Profile  IProfile               public UserProfile                         CreateMap lt User  UserModel gt                 CreateMap lt UserModel  User gt                       Now create a separate class e g Mappings    public class Mappings            public static void RegisterMappings                             var all          Assembly            GetEntryAssembly              GetReferencedAssemblies              Select Assembly Load             SelectMany x   gt  x DefinedTypes             Where type   gt  typeof IProfile  GetTypeInfo   IsAssignableFrom type AsType                   foreach  var ti in all                                var t   ti AsType                    if  t Equals typeof IProfile                                          Mapper Initialize cfg   gt                                                cfg AddProfiles t      Initialise each Profile classe                                                                                     Now in MVC Core web Project in Startup cs file  in the constructor  call Mapping class which will initialize all mappings at the time of application  loading   Mappings RegisterMappings

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about theutz answer   there is no need to specify the IMapper mapper parrameter at the controllers constructor   you can use the Mapper as it is a static member at any place of the code   public class UserController   Controller      public someMethod              Mapper Map lt User  UserDto gt  user

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Asp Net Core 2 2 with AutoMapper Extensions Microsoft DependencyInjection   public class MappingProfile   Profile     public MappingProfile             CreateMap lt Domain  DomainDto gt             In Startup cs  services AddAutoMapper typeof List Handler

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For AutoMapper 9 0 0    public static IEnumerable lt Type gt  GetAutoMapperProfilesFromAllAssemblies                 foreach  var assembly in AppDomain CurrentDomain GetAssemblies                          foreach  var aType in assembly GetTypes                                  if  aType IsClass  amp  amp   aType IsAbstract  amp  amp  aType IsSubclassOf typeof Profile                        yield return aType                                  MapperProfile    public class OrganizationProfile   Profile     public OrganizationProfile           CreateMap lt Foo  FooDto gt            Use CreateMap    Etc   here  Profile methods are the same as configuration methods          In your Startup   services AddAutoMapper GetAutoMapperProfilesFromAllAssemblies                ToArray       In Controller or service  Inject mapper     private readonly IMapper  mapper    Usage   var obj    mapper Map lt TDest gt  sourceObject

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To add onto what Arve Systad mentioned for testing  If for whatever reason you re like me and want to maintain the inheritance structure provided in theutz solution  you can set up the MapperConfiguration like so   var mappingProfile   new MappingProfile    var config   new MapperConfiguration cfg   gt        cfg AddProfile mappingProfile       var mapper   new Mapper config     I did this in NUnit

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Step To Use AutoMapper with ASP NET Core   Step 1  Installing AutoMapper Extensions Microsoft DependencyInjection from NuGet Package     Step 2  Create a Folder in Solution to keep Mappings with Name  Mappings      Step 3  After adding Mapping folder we have added a class with Name  MappingProfile  this name can anything unique and good to understand   In this class  we are going to Maintain all Mappings      Step 4  Initializing Mapper in Startup  ConfigureServices   In Startup Class  we Need to Initialize Profile which we have created and also Register AutoMapper Service     Mapper Initialize cfg   gt  cfg AddProfile lt MappingProfile gt         services AddAutoMapper      Code Snippet to show ConfigureServices Method where we need to Initialize and Register AutoMapper   public class Startup       public Startup IConfiguration configuration                Configuration   configuration             public IConfiguration Configuration   get          public void ConfigureServices IServiceCollection services                services Configure lt CookiePolicyOptions gt  options   gt                           This lambda determines whether user consent for non-essential cookies is needed for a given request              options CheckConsentNeeded   context   gt  true              options MinimumSameSitePolicy   SameSiteMode None                           Start Registering and Initializing AutoMapper          Mapper Initialize cfg   gt  cfg AddProfile lt MappingProfile gt              services AddAutoMapper                End Registering and Initializing AutoMapper          services AddMvc   SetCompatibilityVersion CompatibilityVersion Version 2 1             Step 5  Get Output   To Get Mapped result we need to call AutoMapper Mapper Map and pass Proper Destination and Source   AutoMapper Mapper Map lt Destination gt  source     CodeSnippet       HttpPost      public void Post  FromBody  SchemeMasterViewModel schemeMaster                if  ModelState IsValid                        var mappedresult   AutoMapper Mapper Map lt SchemeMaster gt  schemeMaster

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At the latest versions of asp net core you should use the following initialization   services AddAutoMapper typeof YourMappingProfileClass

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I solved it this way  similar to above but I feel like it s a cleaner solution  Works with  NET Core 3 x Create MappingProfile cs class and populate constructor with Maps  I plan on using a single class to hold all my mappings      public class MappingProfile   Profile               public MappingProfile                         CreateMap lt Source  Dest gt    ReverseMap                     In Startup cs  add below to add to DI  the assembly arg is for the class that holds your mapping configs  in my case  it s the MappingProfile class     add automapper DI services AddAutoMapper typeof MappingProfile      In Controller  use it like you would any other DI object      Route  quot api  controller  quot         ApiController      public class AnyController   ControllerBase               private readonly IMapper  mapper           public AnyController IMapper mapper                         mapper   mapper                             public IActionResult Get int id                        var entity   repository Get id               var dto    mapper Map lt Dest gt  entity                            return Ok dto

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theutz  answer here is very good  I just want to add this   If you let your mapping profile inherit from MapperConfigurationExpression instead of Profile  you can very simply add a test to verify your mapping setup  which is always handy    Fact  public void MappingProfile VerifyMappings         var mappingProfile   new MappingProfile         var config   new MapperConfiguration mappingProfile       var mapper   new Mapper config         mapper as IMapper  ConfigurationProvider AssertConfigurationIsValid

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