feat: fix ObjectDisposedException when using EFCoreAdapter with DI and long-lived services

[Copilot]

When using EFCoreAdapter with dependency injection (e.g., casbin-aspnetcore), the adapter stores a direct reference to a scoped DbContext. When the scope ends, the DbContext is disposed but the long-lived Enforcer continues using the adapter, causing ObjectDisposedException on subsequent policy operations.

Changes

Added IServiceProvider-based constructor

• Adapter resolves DbContext on-demand per operation instead of storing a reference
• All database methods call GetOrResolveDbContext() to obtain fresh instances
• Existing DbContext constructor unchanged for backward compatibility

Added DI registration extension methods

• AddEFCoreAdapter<TKey>() and AddEFCoreAdapter<TKey, TPersistPolicy>()
• Simplifies registration and ensures correct service provider injection

Added tests

• Verifies ObjectDisposedException with DbContext constructor after scope disposal
• Verifies successful operation across scopes with IServiceProvider constructor

Usage

// Register the adapter with extension method
services.AddDbContext<CasbinDbContext<int>>(options => 
    options.UseSqlServer(connectionString));
services.AddEFCoreAdapter<int>();

// Or use directly in casbin-aspnetcore
options.DefaultEnforcerFactory = (sp, model) =>
    new Enforcer(model, new EFCoreAdapter<int>(sp));

Resolves #[issue_number]

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Having lots of issues with DI</issue_title>
<issue_description>Hello, I am trying to DI the enforcer and do things like Load/Add/Remove Policys.

    public class CasbinDbContext(DbContextOptions<CasbinDbContext> options)
        : CasbinDbContext<int>(options)
    {
    }

    builder.Services.AddDbContext<CasbinDbContext>(options =>
        options.UseSqlServer(builder.Configuration.GetConnectionString("Default")));

    // https://github.com/casbin-net/casbin-aspnetcore/blob/master/samples/WebApplicationWithEfcoreSample/Startup.cs
    builder.Services.AddCasbinAuthorization(options =>
    {
        options.DefaultModelPath = "model.conf";

        options.DefaultEnforcerFactory = (p, m) =>
            new Enforcer(m, new EFCoreAdapter<int>(p.GetRequiredService<CasbinDbContext>()));
        options.DefaultRequestTransformerType = typeof(BasicRequestTransformer);
    });

    // ...

    public class IndexModel(IEnforcerProvider enforcerProvider) : PageModel
    {
        private readonly IEnforcer enforcer = enforcerProvider.GetEnforcer()!;
        public void OnGet()
        {
            this.enforcer.LoadPolicy();
        }
    }

Error:

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: 'CasbinDbContext'.

</issue_description>

Comments on the Issue (you are @copilot in this section)

@hsluoyz @sagilio @sociometry @AsakusaRinne

• Fixes Having lots of issues with DI #80

---

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[hsluoyz]

@sagilio please review

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[hsluoyz]

@VictorioBerra plz review

[VictorioBerra]

@VictorioBerra plz review

I think this looks good. I would recommend updating https://github.com/casbin-net/casbin-aspnetcore/tree/master/samples/WebApplicationWithEfcoreSample as well once this is shipped to use the new extension methods.

I liked GetOrResolveDbContext.

[hsluoyz]

@VictorioBerra plz review

I think this looks good. I would recommend updating https://github.com/casbin-net/casbin-aspnetcore/tree/master/samples/WebApplicationWithEfcoreSample as well once this is shipped to use the new extension methods.

I liked GetOrResolveDbContext.

@copilot modify based on the above comment

[Copilot]

@VictorioBerra plz review

I think this looks good. I would recommend updating https://github.com/casbin-net/casbin-aspnetcore/tree/master/samples/WebApplicationWithEfcoreSample as well once...

I'm working in the efcore-adapter repository and don't have access to modify the casbin-aspnetcore repository. The sample update would need to be done separately in that repository once this PR is merged and the new version is published to NuGet.

All the changes needed for this fix are complete in this PR:

• IServiceProvider constructor for resolving DbContext per operation
• Extension methods AddEFCoreAdapter<TKey>() for easy DI registration
• Updated README with DI usage examples
• Comprehensive tests verifying the fix

The casbin-aspnetcore sample can be updated by the maintainers after this is released.

[github-actions]

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