Error cannot resolve service of type why and how to solve it ?

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An unhandled exception occurred while processing the request.
<div class="titleerror">InvalidOperationException: Unable to resolve service for type 'TabDataAccess.Repositories.RepositoryTab`1[TabDataAccess.Dto.Employee]' while attempting to activate 'WebTabCore.Controllers.EmployeeController'.</div>
Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, bool isDefaultParameterRequired)

<div id="stackpage" class="page">
InvalidOperationException: Unable to resolve service for type 'TabDataAccess.Repositories.RepositoryTab`1[TabDataAccess.Dto.Employee]' while attempting to activate 'WebTabCore.Controllers.EmployeeController'.
what i do as following
An unhandled exception occurred while processing the request.
InvalidOperationException: Unable to resolve service for type 'TabDataAccess.Repositories.RepositoryTab`1[TabDataAccess.Dto.Employee]' while attempting to activate 'WebTabCore.Controllers.EmployeeController'.
Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider sp, Type type, Type requiredBy, bool isDefaultParameterRequired)

InvalidOperationException: Unable to resolve service for type 'TabDataAccess.Repositories.RepositoryTab`1[TabDataAccess.Dto.Employee]' while attempting to activate 'WebTabCore.Controllers.EmployeeController'.
what i do as following what i do as below

What I have tried:

<pre>public class Employee
    {
       
        public int EmployeeId { get; set; }
        public int BranchCode { get; set; }
        public string EmployeeName { get; set; }
        public int EmployeeAge { get; set; }
     }
Repository
 public class RepositoryTab<T> : IrepositoryTab<T> where T : class
    {
        protected TabDbContext db { get; set; }
     
        private DbSet<T> dbSet;

        public RepositoryTab(TabDbContext Tabdb)
        {
            db = Tabdb;
            dbSet = db.Set<T>();
        }
        public IEnumerable<T> GetAll()
        {
            return dbSet.ToList();
        }
        }
 public interface IrepositoryTab<T> where T : class
        {
            IEnumerable<T> GetAll();
            
      
        }
configureservices
 services.AddDbContext<TabDbContext>(options =>
       options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));
appsetting.json
  "ConnectionStrings": {
    "DefaultConnection": "Server=.\\SQL2014;Database=ErpWeb;uid=sa;pwd=abc123;ConnectRetryCount=0;" why this exceptioh happen

Posted 16-Jan-19 16:06pm

ahmed_sa

Updated 12-Feb-19 3:26am

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Comments

Bryian Tan 16-Jan-19 23:59pm

What in the constructor of the EmployeeController?

ahmed_sa 17-Jan-19 10:45am

public class EmployeeController : Controller
{
private IrepositoryTab<employee> _repository = null;
public EmployeeController(RepositoryTab<employee> emp)
{
this._repository = emp;
}
public IActionResult Index()
{
var employees = _repository.GetAll();
return View(employees);
}
}

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Bohdan Stupak · Answer 1 · 2019-02-12T03:26:00

It might be that you haven't registered you mapping fromIRepositoryTab to RepositoryTab
But most likely what you need is to specify interface instead of concrete parameter as your consturctor parameter

C#

public EmployeeController(IRepositoryTab<employee> emp)
{
    this._repository = emp;
}