Automapper - Mapper already initialized error

Question

I am using AutoMapper 6.2.0 in my ASP.NET MVC 5 application.

When I call my opinion through the controller, it shows everything correctly. But when I update this view, Visual Studio shows an error:

System.InvalidOperationException: 'Mapper is already initialized. You must call Initialize once per application domain / process. ''

I use AutoMapper in only one controller. No configuration was made anywhere and AutoMapper was not used in any other service or controller.

My controller:

public class StudentsController : Controller
{
    private DataContext db = new DataContext();

    // GET: Students
    public ActionResult Index([Form] QueryOptions queryOptions)
    {
        var students = db.Students.Include(s => s.Father);

        AutoMapper.Mapper.Initialize(cfg =>
        {
            cfg.CreateMap<Student, StudentViewModel>();
        });
            return View(new ResulList<StudentViewModel> {
            QueryOptions = queryOptions,
            Model = AutoMapper.Mapper.Map<List<Student>,List<StudentViewModel>>(students.ToList())
        });
    }

    // Other Methods are deleted for ease...

Error in the controller:

My model class:

public class Student
{
    [Key]
    public int Id { get; set; }
    public string Name { get; set; }
    public string CNIC { get; set; }
    public string FormNo { get; set; }
    public string PreviousEducaton { get; set; }
    public string DOB { get; set; }
    public int AdmissionYear { get; set; }

    public virtual Father Father { get; set; }
    public virtual Sarparast Sarparast { get; set; }
    public virtual Zamin Zamin { get; set; }
    public virtual ICollection<MulaqatiMehram> MulaqatiMehram { get; set; }
    public virtual ICollection<Result> Results { get; set; }
}

My ViewModel class:

public class StudentViewModel
{
    [Key]
    public int Id { get; set; }

    public string Name { get; set; }
    public string CNIC { get; set; }
    public string FormNo { get; set; }
    public string PreviousEducaton { get; set; }
    public string DOB { get; set; }
    public int AdmissionYear { get; set; }

    public virtual FatherViewModel Father { get; set; }
    public virtual SarparastViewModel Sarparast { get; set; }
    public virtual ZaminViewModel Zamin { get; set; }
}

Answer 1

, StudentsController - , , Mapper, "Mapper ".

AutoMapper?

Mapper, AppDomain. , , , Global.asax ASP.NET.

- .

App_Start/AutoMapperConfig.cs:

public class AutoMapperConfig
{
    public static void Initialize()
    {
        Mapper.Initialize(cfg =>
        {
            cfg.CreateMap<Student, StudentViewModel>();
            ...
        });
    }
}

Global.asax.cs

protected void Application_Start()
{
    App_Start.AutoMapperConfig.Initialize();
}

() .

public class StudentsController : Controller
{
    public ActionResult Index(int id)
    {
        var query = db.Students.Where(...);

        var students = AutoMapper.Mapper.Map<List<StudentViewModel>>(query.ToList());

        return View(students);
    }
}

Answer 2

/ , , AutoMapper.Mapper.Reset() initialize. , , .

: AutoMapper.

Answer 3

, 6.1.1

 Mapper.Initialize(cfg => cfg.CreateMap<ContactModel, ContactModel>()
            .ConstructUsing(x => new ContactModel(LoggingDelegate))
            .ForMember(x => x.EntityReference, opt => opt.Ignore())
        );

6.2, . Automapper, Mapper, :

 var mapper = new MapperConfiguration(cfg => cfg.CreateMap<ContactModel, ContactModel>()
            .ConstructUsing(x => new ContactModel(LoggingDelegate))
            .ForMember(x => x.EntityReference, opt => opt.Ignore())).CreateMapper();

        var model = mapper.Map<ContactModel>(this);

Answer 4

" " AutoMapper API , System.InvalidOperationException: Mapper already initialized. You must call Initialize once per application domain/process. Mapper already initialized. You must call Initialize once per application domain/process.

, TestServer xUnit ServiceCollectionExtensions.UseStaticRegistration fixure fixure false :

public TestServerFixture()
{
    ServiceCollectionExtensions.UseStaticRegistration = false; // <-- HERE

    var hostBuilder = new WebHostBuilder()
        .UseEnvironment("Testing")
        .UseStartup<Startup>();

    Server = new TestServer(hostBuilder);
    Client = Server.CreateClient();
}

Answer 5

Mapper.Reset()

[TearDown]
public void TearDown()
{
    Mapper.Reset();
}

Answer 6

automapper Static API Instance API, Mapper Static API, mapper.Reset(), mapper, .

API-

var students = db.Students.Include(s => s.Father);

var config = new MapperConfiguration(cfg => {
               cfg.CreateMap<Student, StudentViewModel>();        
             });

IMapper iMapper = config.CreateMapper();          
return iMapper.Map<List<Student>, List<StudentViewModel>>(students);

Answer 7

Automapper 8.0.0

    AutoMapper.Mapper.Reset();
    Mapper.Initialize(
     cfg => {
         cfg.CreateMap<sourceModel,targetModel>();
       }
    );

Answer 8

Mapper.Reset().

:

public static TDestination MapToObject<TSource, TDestination>(TSource Obj)
{
    Mapper.Initialize(cfg => cfg.CreateMap<TSource, TDestination>());
    TDestination tDestination = Mapper.Map<TDestination>(Obj);
    Mapper.Reset();
    return tDestination;
}

Answer 9

Mapper UnitTest , Mapper.Reset()

//Your mapping.
 public static void Initialize()
 {
   Mapper.Reset();                    
   Mapper.Initialize(cfg =>
   {  
       cfg.CreateMap<***>    
   }

//Your test classes.

 [TestInitialize()]
 public void Initialize()
 {
      AutoMapping.Initialize();
 }

Answer 10

If you use MsTest, you can use the AssemblyInitialize attribute so that the mapping is configured only once for this assembly (here is the test assembly). This is usually added to the base class of controller module tests.

[TestClass]
public class BaseUnitTest
{
    [AssemblyInitialize]
    public static void AssemblyInit(TestContext context)
    {
        AutoMapper.Mapper.Initialize(cfg =>
        {
            cfg.CreateMap<Source, Destination>()
                .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.EmailAddress));
        });
    }
}

Hope this answer helps

Answer 11

private static bool _mapperIsInitialized = false;
        public InventoryController()
        {

            if (!_mapperIsInitialized)
            {

                _mapperIsInitialized = true;
                Mapper.Initialize(
                    cfg =>
                    {
                        cfg.CreateMap<Inventory, Inventory>()
                        .ForMember(x => x.Orders, opt => opt.Ignore());
                    }
                    );
            }
        }