'Missing type map configuration or unsupported mapping.' Automapperexception in ASP.NET Core WebApi - asp.net-core

Question

I'm trying to add AutoMapper to a API (built using ASP.NET Core 3) but it gives me the 'Missing type map configuration or unsupported mapping.'-exception and my google-searches doesn't help me at all... :).
The exception is thrown (as described below) in "GetAllObject1"-method
This is my current setup:
[HttpGet]
public IActionResult GetAllObject1()
{
var object1Items = _myService.GetAllObject1();
Object1ViewModel ouViewModel = _mapper.Map<Object1ViewModel>(Object1Items); // <= This line gives the exception above!!
return Ok(ouViewModel);
}
"AutoMapping.cs":
namespace DataAccess.AutoMapper
{
public class AutoMapping : Profile
{
public AutoMapping()
{
CreateMap < KollOrganizationalUnit, KollOrganizationalUnitViewModel>();
}
}
}
"Startup.cs":
public virtual void ConfigureServices(IServiceCollection services)
{
if (services == null)
throw new ArgumentNullException(nameof(services));
services.AddMvc()
.SetCompatibilityVersion(CompatibilityVersion.Version_3_0);
services.AddControllers()
.AddNewtonsoftJson(options =>
{
options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;
})
.AddJsonOptions(options =>
{
options.JsonSerializerOptions.IgnoreNullValues = true;
});
services.AddDbContext<RepositoryContext>(opts => opts.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
services.RegisterDAL();
services.RegisterBizServices();
services.AddSwaggerGen(c =>
{
c.SwaggerDoc("v1", new OpenApiInfo
{
Version = "v1",
Title = "API",
Description = "Integration API for XXX",
TermsOfService = new Uri("https://www.xxx.se/terms-of-service"),
Contact = new OpenApiContact()
{
Name = "Integrationcontact",
Email = "integration#xxx.se",
Url = new Uri("https://www.xxx.se")
},
});
});
services.AddAutoMapper(typeof(Startup).Assembly);
}
Am I missing something obious here?

Answer 1

It's hard to say without knowing the return type of _myService.GetAllObject1(), but it seems like it's returning a collection of Object1Unit. If that's the case, you can try something like:
IEnumerable<Object1ViewModel> ouViewModels = Object1Items.Select(x => _mapper.Map<Object1ViewModel>(x));
return Ok(ouViewModels);
If you're trying to map a collection to a single item, you have to tell AutoMapper how to do that or you will get the exception you're seeing (your AutoMapping class only creates a map from a single item to a single item).