EF Core how to get a DBContext in a class instance? - asp.net-core

Question

The ASP NET Core project uses the Entity Framework Core.
From the method of the Home controller I call Task.Run for the method of the instance of the class MyClass, where I need to access the data from the database.
I tried to pass _dbContext to the constructor of the MyClass class, but I get the exception
Cannot access a disposed object.
HomeController
[Route("api/[controller]")]
[EnableCors("AllowAllOrigin")]
[ApiController]
public class HomeController : ControllerBase
{
private readonly DataBaseContext _dbContext;
public HomeController (DataBaseContext dbContext)
{
_dbContext = dbContext;
}
[EnableCors("AllowAllOrigin")]
[HttpPost("[action]")]
public string UpdateBotSettings()
{
MyClass myClass = new MyClass(_dbContext);
Task task = Task.Run(() => myClass.AnyMethod());
}
}
MyClass
public class MyClass
{
private readonly DataBaseContext _dbContext;
public MyClass(DataBaseContext dbContext)
{
_dbContext = dbContext;
}
public async void AnyMethodAsync()
{
MyData myData = _dbContext.AnyData.Where(d => d.id == 1).FirstOrDefault(); // <- exception
}
}
Startup
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
string connection = Configuration.GetConnectionString("ConnectionDB");
services.AddDbContext<DataBaseContext>(options => options.UseSqlServer(connection));
// another code
}
Can you please tell me how to access dbContext inside an instance of MyClass?

Answer 1

Most important mistake in your code is that you are using async void in your AnyMethodAsync() method of the Myclass. Don't use async void in your code, instead use async Task. Here is the details: C# – beware of async void in your code
So write your AnyMethodAsync() as follows:
public async Task AnyMethodAsync()
{
MyData myData = await _dbContext.AnyData.Where(d => d.id == 1).FirstOrDefault();
}
Now you can register your MyClass to the ASP.NET Core DI container as follows:
public void ConfigureServices(IServiceCollection services)
{
services.AddScoped<MyClass>(); // <-- here it is
string connection = Configuration.GetConnectionString("ConnectionDB");
services.AddDbContext<DataBaseContext>(options => options.UseSqlServer(connection));
// another code
services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);
}
Now use it as follows:
[Route("api/[controller]")]
[EnableCors("AllowAllOrigin")]
[ApiController]
public class HomeController : ControllerBase
{
private readonly DataBaseContext _dbContext;
private readonly MyClass _myClass
public HomeController (DataBaseContext dbContext, MyClass myClass)
{
_dbContext = dbContext;
_myClass = myClass;
}
[EnableCors("AllowAllOrigin")]
[HttpPost("[action]")]
public async Task<string> UpdateBotSettings()
{
await _myClass.AnyMethod();
// rest of codes
}
}