Error: "Some services are not able to be constructed"

Question

I am getting this error can anyone help me ?

 

Inner Exception 1:

InvalidOperationException: Error while validating the service descriptor 'ServiceType: LServices.Interfaces.IUpdater Lifetime: Scoped ImplementationType: LServices.IUpdater ': Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContext' while attempting to activate 'LServices.Repositories.Base.Repository`1[LServices.Entities.Students]'.

Inner Exception 2:

InvalidOperationException: Unable to resolve service for type 'Microsoft.EntityFrameworkCore.DbContext' while attempting to activate 'LServices.Repositories.Base.Repository`1[LServices.Entities.Students]]'.

 

I have my files as below :

Startup.cs

public void ConfigureServices(IServiceCollection services)
{
services.AddDbContext(item =>
item.UseSqlServer(Configuration.GetConnectionString("DBConnection")));
services.AddTransient();
services.AddTransient(typeof(IRepository<>), typeof(Repository<>));
services.AddTransient(typeof(IGenericRepository<,>), typeof(GeneralRepository<,>));
}
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
// var appl = app.ApplicationServices.GetServices();
var appl2 = app.ApplicationServices.GetService();
appl2.GetFloorsDataInDb();
app.UseRouting();
app.UseEndpoints(endpoints =>
{
endpoints.MapGet("/", async context =>
{
await context.Response.WriteAsync("Hello World!");
});
});
}

Context class :

public class LServiceContext : DbContext
{
public LServiceContext (DbContextOptions options) : base(options)
{
}
public DbSet<Student> Student{ get; set; }
}

The class which I want to class in startup.cs

namespace LServiceJob
{
public classUpdater : IUpdater
{
private IRepository studentsRepository;
public FloorsInfoUpdater(IRepository studentRepository)
{
this.studentRepository= studentRepository;
}
public List GetFloorsDataInDb()
{
List groupedFloors = this.studentRepository.GetAll().ToList();
return groupedstuents;
}
}
}