I'm listening for an incoming Azure service bus message. Following the documentation and receiving the message, I parse the message body and then I want to connect to my DB to edit an entry and then save. But I'm getting this error below when trying to make the call
var ybEvent = await _unitOfWork.Repository<YogabandEvent>().GetEntityWithSpec(spec);
Error
Cannot access a disposed context instance. A common cause of this error is disposing a context instance that was resolved from dependency injection and then later trying to use the same context instance elsewhere in your application. This may occur if you are calling 'Dispose' on the context instance, or wrapping it in a using statement. If you are using dependency injection, you should let the dependency injection container take care of disposing context instances.\nObject name: 'DataContext'.
Here is the full service with the method that listens for and picks up incoming Azure messages. Error is on the last line of MessageHandler()
FYI - If I remove the 'await' on the DB call, I still get the same error for a disposed context.
QUESTION - how do I fix this?
public class ServiceBusConsumer : IServiceBusConsumer
{
private readonly IConfiguration _config;
private readonly ServiceBusClient _queueClient;
private readonly ServiceBusProcessor _processor;
private readonly IUnitOfWork _unitOfWork;
private readonly IEventConsumer _eventConsumer;
public ServiceBusConsumer(IConfiguration config, IEventConsumer eventConsumer, IUnitOfWork unitOfWork)
{
_config = config;
_unitOfWork = unitOfWork;
_eventConsumer = eventConsumer;
_queueClient = new ServiceBusClient(_config["ServiceBus:Connection"]);
_processor = _queueClient.CreateProcessor(_config["ServiceBus:Queue"], new ServiceBusProcessorOptions());
}
public void RegisterOnMessageHandlerAndReceiveMessages() {
_processor.ProcessMessageAsync += MessageHandler;
_processor.ProcessErrorAsync += ErrorHandler;
_processor.StartProcessingAsync();
}
private async Task MessageHandler(ProcessMessageEventArgs args)
{
string body = args.Message.Body.ToString();
JObject jsonObject = JObject.Parse(body);
var eventStatus = (string)jsonObject["EventStatus"];
await args.CompleteMessageAsync(args.Message);
var spec = new YogabandEventWithMessageIdSpecification(args.Message.SequenceNumber);
// error here...
var ybEvent = await _unitOfWork.Repository<YogabandEvent>().GetEntityWithSpec(spec);
// do something then save
}
private Task ErrorHandler(ProcessErrorEventArgs args)
{
var error = args.Exception.ToString();
return Task.CompletedTask;
}
}
Here is my unit of work
public IGenericRepository<TEntity> Repository<TEntity>() where TEntity : class // : BaseEntity
{
if(_repositories == null)
_repositories = new Hashtable();
var type = typeof(TEntity).Name;
if (!_repositories.ContainsKey(type))
{
var repositoryType = typeof(GenericRepository<>);
var repositoryInstance = Activator.CreateInstance(repositoryType.MakeGenericType(typeof(TEntity)), _context);
_repositories.Add(type, repositoryInstance);
}
return (IGenericRepository<TEntity>) _repositories[type];
}
I tried to call my generic repo directly inside the handler but that still fails with the dispose error.
Here is the call I changed in the handler, now I call the gen repo instead of the unit of work
var ybEvent = await _eventsRepo.GetEntityWithSpec(spec);
Here is GetEntityWIthSpec() from my generic repo
public async Task<T> GetEntityWithSpec(ISpecification<T> spec)
{
return await ApplySpecification(spec).FirstOrDefaultAsync();
}
private IQueryable<T> ApplySpecification(ISpecification<T> spec)
{
return SpecificationEvaluator<T>.GetQuery(_context.Set<T>().AsQueryable(), spec);
}
FYI - here is how I init my repo call
private readonly IGenericRepository<YogabandEvent> _eventsRepo;
then I inject it into the constructor
public ServiceBusConsumer(IConfiguration config, IEventConsumer eventConsumer, IUnitOfWork unitOfWork, IGenericRepository<YogabandEvent> eventsRepo)
{
_config = config;
_unitOfWork = unitOfWork;
_eventConsumer = eventConsumer;
_eventsRepo = eventsRepo;
_queueClient = new ServiceBusClient(_config["ServiceBus:Connection"]);
_processor = _queueClient.CreateProcessor(_config["ServiceBus:Queue"], new ServiceBusProcessorOptions());
}
Code that starts the ServiceBusConsumer it's in Main()
public static async Task Main(string[] args)
{
var host = CreateHostBuilder(args).Build();
using (var scope = host.Services.CreateScope())
{
var services = scope.ServiceProvider;
var loggerFactory = services.GetRequiredService<ILoggerFactory>();
try
{
// do some work here
// https://stackoverflow.com/questions/48590579/cannot-resolve-scoped-service-from-root-provider-net-core-2
var bus = services.GetRequiredService<IServiceBusConsumer>();
bus.RegisterOnMessageHandlerAndReceiveMessages();
}
catch (Exception ex)
{
var logger = loggerFactory.CreateLogger<Program>();
logger.LogError(ex, "An error occured during migration");
}
}
host.Run();
}
Here is my unit of work
public class UnitOfWork : IUnitOfWork
{
private readonly DataContext _context;
private Hashtable _repositories;
public UnitOfWork(DataContext context)
{
_context = context;
}
public async Task<int> Complete()
{
return await _context.SaveChangesAsync();
}
public void Dispose()
{
_context.Dispose();
}
public IGenericRepository<TEntity> Repository<TEntity>() where TEntity : class // : BaseEntity
{
if(_repositories == null)
_repositories = new Hashtable();
var type = typeof(TEntity).Name;
if (!_repositories.ContainsKey(type))
{
var repositoryType = typeof(GenericRepository<>);
var repositoryInstance = Activator.CreateInstance(repositoryType.MakeGenericType(typeof(TEntity)), _context);
_repositories.Add(type, repositoryInstance);
}
return (IGenericRepository<TEntity>) _repositories[type];
}
}
