Unable to resolve service for type at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService(IServiceProvider - asp.net-core

Question

I am attempting to receive data from the server controller, stocks.
I get this error:
"System.InvalidOperationException: Unable to resolve service for type myBackEnd.Models.StockContext' while attempting to activate 'myBackEnd.Controllers.StockController'.
at Microsoft.Extensions.DependencyInjection.ActivatorUtilities.GetService
(IServiceProvider sp, Type type, Type requiredBy, Boolean
isDefaultParameterRequired"
Here is my stocks controller code:
namespace myBackEnd.Controllers
{
[Route("api/stock")]
[Produces("application/json")]
public class StockController : ControllerBase
{
private readonly int fastEmaPeriod = 10;
private readonly IHttpClientFactory _httpClientFactory;
private readonly Models.StockContext _context;
public StockController(Models.StockContext context, IHttpClientFactory httpClientFactory)
{
_httpClientFactory = httpClientFactory;
_context = context;
}
// POST api/values
[HttpPost]
public async Task<IActionResult> Post([FromBody]Models.Stock stock)
{
_context.Stocks.Add(stock);
await _context.SaveChangesAsync();
return Ok(stock);
}
This is the startup.cs code:
public void ConfigureServices(IServiceCollection services)
{
services.AddCors(o => o.AddPolicy("MyPolicy", corsBuilder =>
{
corsBuilder.AllowAnyOrigin()
.AllowAnyMethod()
.AllowAnyHeader()
.AllowCredentials();
}));
services.AddDbContext<DataContext>(x => x.UseInMemoryDatabase("TestDb"));
services.AddHttpClient();
services.AddAutoMapper();
// configure strongly typed settings objects
var appSettingsSection = Configuration.GetSection("AppSettings");
services.Configure<AppSettings>(appSettingsSection);
// configure jwt authentication
var appSettings = appSettingsSection.Get<AppSettings>();
var key = Encoding.ASCII.GetBytes(appSettings.Secret);
services.AddAuthentication(x =>
{
x.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
x.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
})
.AddJwtBearer(x =>
{
x.Events = new JwtBearerEvents
{
OnTokenValidated = context =>
{
var userService = context.HttpContext.RequestServices.GetRequiredService<IUserService>();
var userId = int.Parse(context.Principal.Identity.Name);
var user = userService.GetById(userId);
if (user == null)
{
// return unauthorized if user no longer exists
context.Fail("Unauthorized");
}
return Task.CompletedTask;
}
};
x.RequireHttpsMetadata = false;
x.SaveToken = true;
x.TokenValidationParameters = new TokenValidationParameters
{
ValidateIssuerSigningKey = true,
IssuerSigningKey = new SymmetricSecurityKey(key),
ValidateIssuer = false,
ValidateAudience = false
};
});
// configure DI for application services
services.AddScoped<IUserService, UserService>();
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
}
This worked before I added the registration, login and
// configure DI for application services
services.AddScoped();

Answer 1

The problem was the DB context was not registered for dependency injection.
Adding:
services.AddDbContext<Models.StockContext>(opt => opt.UseInMemoryDatabase("item"));
fixed the problem.