Calling IRepository.GetQueryableAsync() in a Background Job causes System.ObjectDisposedException

[ejohnson-dotnet]

Is there an existing issue for this?

• I have searched the existing issues

Description

Calling a simple repository query in a BackgroundJob causes a System.ObjectDisposedException.

System.ObjectDisposedException: 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.
Object name: 'BookStoreDbContext'.
   at Microsoft.EntityFrameworkCore.DbContext.CheckDisposed()
   at Microsoft.EntityFrameworkCore.DbContext.get_ContextServices()
   at Microsoft.EntityFrameworkCore.DbContext.get_Model()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityType()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.CheckState()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.get_EntityQueryable()
   at Microsoft.EntityFrameworkCore.Internal.InternalDbSet`1.System.Collections.Generic.IEnumerable<TEntity>.GetEnumerator()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Acme.BookStore.Books.BooksBackgroundJob.ExecuteAsync(BooksJobArgs args) in C:\Code\Acme.BookStore\Acme.BookStore\src\Acme.BookStore.Application\Books\BooksBackgroundJob.cs:line 24

This is the code that causes the exception:

var books = (await _repository.GetQueryableAsync())
    .Where(b => b.Name.StartsWith(args.Name))
    .ToList();

Reproduction Steps

• Create a new project called Acme.BookStore.
• Add a BooksBackgroundJob.cs file with this:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Volo.Abp.BackgroundJobs;
using Volo.Abp.DependencyInjection;
using Volo.Abp.Domain.Repositories;

namespace Acme.BookStore.Books;

public class BooksBackgroundJob : AsyncBackgroundJob<BooksJobArgs>, ITransientDependency
{
    private readonly IRepository<Book> _repository;
    public BooksBackgroundJob(IRepository<Book> repository)
    {
        _repository = repository;
    }

    public override async Task ExecuteAsync(BooksJobArgs args)
    {
        try
        {
            var books = (await _repository.GetQueryableAsync())
                //.Where(b => b.Name.StartsWith(args.Name))
                .ToList();


            System.Diagnostics.Trace.WriteLine("Found " + books.Count);
        }
        catch (Exception ex) {
            System.Diagnostics.Trace.WriteLine(ex);
        }


        System.Diagnostics.Trace.WriteLine("Finished.");
    }
}

• Add a BooksJobArgs.cs file with this:

namespace Acme.BookStore.Books;

public class BooksJobArgs
{

    public string Name { get; set; }
}

• Start a new job by calling this `_backgroundJobManager.EnqueueAsync(new BooksJobArgs() { Name = "test" });

Acme.BookStore.zip

`

Expected behavior

It should not throw this exception.

Actual behavior

No response

Regression?

No response

Known Workarounds

No response

Version

9.1.0

User Interface

Common (Default)

Database Provider

EF Core (Default)

Tiered or separate authentication server

None (Default)

Operation System

Windows (Default)

Other information

No response

[maliming]

hi

Try to begin a new uow in your ExecuteAsync method.

https://abp.io/docs/latest/framework/architecture/domain-driven-design/unit-of-work?_redirected=B8ABF606AA1BDF5C629883DF1061649A#begin-a-new-unit-of-work

[ejohnson-dotnet]

Yes adding a new UnitOfWork does fix the issue.

What is confusing is that this line works fine without a UOW

var books = await _repository.GetListAsync(b => b.Name.StartsWith(args.Name));

This also works without a UOW

await _repository.FindAsync(b => b.Name.StartsWith(args.Name));

[maliming]

Each method of the repository starts a new uow if there is no current uow.

GetQueryableAsync starts and ends(dispose DbContext) an uow, and the ToList method throws an exception because DbContext is gone.

[ejohnson-dotnet]

Thanks for the clarification and your help.

[Piupiudiu]

method of the repository

I have read the webpage https://abp.io/dhttps://abp.io/docs/latest/framework/architecture/domain-driven-design/unit-of-work#conventions.
For example, The following method types:

BackgroundWorker DoWorkAsync
BackgroundJob ExecuteAsync
DistributedEventHandler HandleEventAsync

If I were to use the methods of the repository, it would be best to use [UnitOfWork]?