ObjectDisposedException what to do

The error message you’re seeing, “System.ObjectDisposedException: Cannot access a disposed context instance,” typically occurs when you attempt to use a database context that has already been disposed of. This is a common issue when working with Entity Framework Core and dependency injection in ASP.NET Core. To resolve this error, you should follow these best practices:

1. Use Dependency Injection: Make sure you are properly using dependency injection to inject the LabexamContext into your services or controllers. Avoid manually creating and disposing of the context.
2. Lifetime Management: Ensure that you have configured the appropriate lifetime for your DbContext. In ASP.NET Core, you typically use one of the following lifetimes for DbContext:

• Transient: A new instance of the context is created every time it’s requested. This is suitable for short-lived operations.
• Scoped: A single instance of the context is created and shared within the scope of a single HTTP request. This is suitable for most web applications.
• Singleton: A single instance of the context is created and shared across the entire application’s lifetime. This should be used with caution and only in specific scenarios.

1. Dispose Pattern: Do not manually call Dispose() on the DbContext. Let the dependency injection container manage the disposal.

Here’s an example of how you can configure the DbContext’s lifetime in your Startup.cs:

public void ConfigureServices(IServiceCollection services)
{
    // Configure DbContext with the appropriate lifetime (Scoped in this example)
    services.AddDbContext<LabexamContext>(options =>
    {
        options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection"));
    }, ServiceLifetime.Scoped);

    // Other service registrations...
}

If you’re still encountering the error, please ensure that you’re not trying to use the DbContext outside of its intended scope or after it has been disposed.

Review the places in your code where you access the DbContext and make sure it’s done within the appropriate scope.

If you have async operations, ensure that you await them properly to avoid accessing the disposed context.