Concurrent requests when using Ninject and DbContext - asp.net-mvc

Question

Here is my project responsible for data:
public interface IRepository<T> where T : class
{
IQueryable<T> All();
T GetById(int id);
void Add(T entity);
void Update(T entity);
....
}
EF implement IRepository
public class GenericRepository<T> : IRepository<T> where T : class
{
public GenericRepository() : this(new ApplicationDbContext())
{
}
public GenericRepository(DbContext context)
{
if (context == null)
{
throw new ArgumentException("An instance of DbContext is required to use this repository.", "context");
}
this.Context = context;
this.DbSet = this.Context.Set<T>();
}
protected IDbSet<T> DbSet { get; set; }
protected DbContext Context { get; set; }
public virtual IQueryable<T> All()
{
return this.DbSet.AsQueryable();
}
public virtual T GetById(int id)
{
return this.DbSet.Find(id);
}........
I use unit of work pattern
public interface IUowData : IDisposable
{
IRepository<House> Houses { get; }
IRepository<Floor> Floors { get; }
...
int SaveChanges();
}
And this is his implementation
public class UowData:IUowData
{
private readonly DbContext context;
private readonly Dictionary<Type, object> repositories = new Dictionary<Type, object>();
public UowData(){}
public UowData(DbContext context)
{
this.context = context;
}
private IRepository<T> GetRepository<T>() where T : class
{
if (!this.repositories.ContainsKey(typeof(T)))
{
var type = typeof(GenericRepository<T>);
this.repositories.Add(typeof(T), Activator.CreateInstance(type, this.context));
}
return (IRepository<T>)this.repositories[typeof(T)];
}
public int SaveChanges()
{
return this.context.SaveChanges();
}
public void Dispose()
{
this.context.Dispose();
}
The second project is of type Web API through which I try to access data from database:
public class ArduinoController : ApiController
{
private IEmailSender sender;
private IUowData data;
public ArduinoController(IEmailSender sender, IUowData data)
{
this.sender = sender;
this.data = data;
}
[HttpPost]
[ActionName("PostAlarm")]
public void PostAlarm(dynamic sensorJson)
{
var alartModel = this.data.Sensors.All()
.....
When I try to use Ninject dependancy resolve i get exception:
"The context cannot be used while the model is being created. This exception may be thrown if the context is used inside the OnModelCreating method or if the same context instance is accessed by multiple threads concurrently. Note that instance members of DbContext and related classes are not guaranteed to be thread safe.".
Everything works fine if I fetch one page at a time. I am using a simple tool 'XENU' to fetch multiple pages simultaneously. This is when I get errors with DBContext by fetching multiple pages at a time.
public static class NinjectWebCommon
{
private static readonly Bootstrapper bootstrapper = new Bootstrapper();
public static void Start()
{
DynamicModuleUtility.RegisterModule(typeof(OnePerRequestHttpModule));
DynamicModuleUtility.RegisterModule(typeof(NinjectHttpModule));
bootstrapper.Initialize(CreateKernel);
}
public static void Stop()
{
bootstrapper.ShutDown();
}
private static IKernel CreateKernel()
{
var kernel = new StandardKernel();
kernel.Bind<Func<IKernel>>().ToMethod(ctx => () => new Bootstrapper().Kernel);
kernel.Bind<IHttpModule>().To<HttpApplicationInitializationHttpModule>();
RegisterServices(kernel);
System.Web.Http.GlobalConfiguration.Configuration.DependencyResolver = new Ninject.WebApi.DependencyResolver.NinjectDependencyResolver(kernel);
return kernel;
}
private static void RegisterServices(IKernel kernel)
{
EmailSettings emailSettings = new EmailSettings
{
ServerName = Settings.Default.EmailServerName,
...
};
kernel.Bind<IEmailSender>().To<EmailSender>().WithConstructorArgument("settings", emailSettings);
kernel.Bind<IUowData>().To<UowData>().InRequestScope().WithConstructorArgument("context",new ApplicationDbContext());
}
}

Answer 1

.WithConstructorArgument("context",new ApplicationDbContext());
results in one DB Context for the whole application. Remove that and add a binding instead.
.Bind<DbContext>().To<ApplicationDbContext>().InRequestScope();