Internal server error in dot net mvc: unable to resolve service - asp.net-mvc

Question

I am trying to use MVC with a controller a view a model and the database.
But I premise I do not know how to use entity framework in my case to connect the model and the database. So I get this runtime error:
"InvalidOperationException: Unable to resolve service for type 'WebCoreFly.Models.FlightsList' while attempting to activate 'WebCoreFly.Controllers.HomeController"
My code consists in:
the controller code:
public class HomeController : Controller
{
private FlightsList l;
public HomeController(FlightsList theList)
{ l = theList; }
public ViewResult Index()
{
return View(l.Flights);
}
}
the Model Code for Flights:
public partial class Flights
{
public long ID { get; set; }
public long Id_Destination { get; set; }
public string Id_Source { get; set; }
public string Nome { get; set; }
public string Company { get; set; }
public System.DateTime Time { get; set; }
public string Id_Plane { get; set; }
public Nullable<System.DateTime> TimeOfArrival { get; set; }
}
and the model for FlightsList:
public class FlightsList
{
private FlyDBContext context;
public FlightsList(FlyDBContext ctx)
{
context = ctx;
}
public IQueryable<Flights> Flights => context.Flights;
}
finally I have defined my dbcontext:
public class FlyDBContext : DbContext
{
public FlyDBContext(DbContextOptions<FlyDBContext> options)
: base(options)
{
}
public DbSet<WebCoreFly.Models.Passengers> Passengers { get; set; }
public DbSet<WebCoreFly.Models.Bookings> Bookings { get; set; }
public DbSet<WebCoreFly.Models.Flights> Flights { get; set; }
}
And in my startup code, I configure services to accept my dbcontext with a link to Existing SQL Database called Fly:
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc();
services.AddDbContext<FlyDBContext>(options =>
options.UseSqlServer(#"Data Source=(localdb)\MSSQLLocalDB;Initial Catalog=Fly;Integrated Security=True;Connect Timeout=30;Encrypt=False;TrustServerCertificate=False;ApplicationIntent=ReadWrite;MultiSubnetFailover=False"));
}
And this is the Configure method of startup:
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
if (env.IsDevelopment())
{
app.UseBrowserLink();
app.UseDeveloperExceptionPage();
}
else
{
app.UseExceptionHandler("/Home/Error");
}
app.UseStaticFiles();
app.UseMvc(routes =>
{
routes.MapRoute(
name: "default",
template: "{controller=Home}/{action=Index}/{id?}");
});
}
My question is: who is responsible to pass to my controller the flights list? and since the flightlist is tied to the dbcontext, is the problem somehow related to the fact I did not use entityframework? (For semplicity Idid not post the code for my view, but I can do it if necessary)

Answer 1

the issue is coming because of the dependency Injection. Here How the application would know that Flights List object requires in Home Controller. To fix this you have to configure it in StartUp.Cs class Configure Service method.
services.AddSingelton<FlightsList>();
There are various ways to configure it like Transient, AddScoped etc.
It is better if you use repository pattern here. Register here the Interface. like following.
services.AddSingelton<IRepository, FlightsList>();
In controller side.
public class HomeController : Controller
{
private IRepository l;
public HomeController(IRepository theList)
{ l = theList; }
public ViewResult Index()
{
return View(l.Flights);
}
}
Hope it will help.