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How to Inject AppDbContext in Wpf core Applications using caliburn micro

I want to add my AppDbContext for every request in my WPFapp.
I'm using caliburn.micro's simple container for dependency injection and I'm wondering How should I register my AppDbContext per request.
Because I should register a pre-constructed instance of it for configure method using _container.Instance(_db) or it will throw a null exception when I start the app.
after that if I say _container.PerRequest<AppDbContext, AppDbContext>() for example, it will throw an exception and says that "Sequence contains more than one element".
if I don't use PerRequest<AppDbContext, AppDbContext>() It will throw a null exception in the class where I Injected AppDbContext in constructor.
How should I register this service?
my Bootstrapper Class:
public class Bootstrapper : BootstrapperBase
{
private SimpleContainer _container = new SimpleContainer();
private AppDbContext _db;
public Bootstrapper()
{
Initialize();
var options = new DbContextOptionsBuilder<AppDbContext>()
.UseJet(#"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=F:\AccessDatabase \TestDatabase1.accdb;")
.Options;
_db = new AppDbContext(options);
ConventionManager.AddElementConvention<PasswordBox>(
PasswordBoxHelper.BoundPasswordProperty,
"Password",
"PasswordChanged");
}
protected override void Configure()
{
_container.Instance(_container);
_container.Singleton<IWindowManager, WindowManager>();
_container.Singleton<IEventAggregator, EventAggregator>();
_container.PerRequest<DataAccess, DataAccess>();
_container.Instance(_db);
_container.PerRequest<AppDbContext, AppDbContext>();
GetType().Assembly.GetTypes()
.Where(type => type.IsClass)
.Where(type => type.Name.EndsWith("ViewModel"))
.ToList()
.ForEach(viewModelType => _container.RegisterPerRequest(
viewModelType, viewModelType.ToString(), viewModelType));
}
protected override async void OnStartup(object sender, StartupEventArgs e)
{
await DisplayRootViewForAsync<ShellViewModel>();
}
protected override object GetInstance(Type service, string key)
{
return _container.GetInstance(service, key);
}
protected override IEnumerable<object> GetAllInstances(Type service)
{
return _container.GetAllInstances(service);
}
protected override void BuildUp(object instance)
{
_container.BuildUp(instance);
}
}

How do I register modules with constructors in autofac?

How do I register modules with constructors in autofac?
I have the following modules:
public class MediatRModule : Module
{
protected override void Load(ContainerBuilder builder)
{
builder.RegisterMediatR(typeof(ApplicationAssemblyMarker).Assembly);
}
}
public class PersistenceModule : Module
{
public string ConnectionString { get; }
public PersistenceModule(string connectionString)
{
if (string.IsNullOrWhiteSpace(connectionString))
throw new ArgumentException("Value cannot be null or whitespace.", nameof(connectionString));
ConnectionString = connectionString;
}
protected override void Load(ContainerBuilder builder)
{
builder.RegisterType<SqlConnectionFactory>()
.As<ISqlConnectionFactory>()
.WithParameter("connectionString", ConnectionString)
.InstancePerLifetimeScope();
builder
.RegisterGeneric(typeof(AsyncRepository<>))
.As(typeof(IAsyncRepository<>))
.InstancePerLifetimeScope();
}
}
PersistenceModule it contains a constructor and I can't register all modules via RegisterAssemblyModules in the startup method.
public void ConfigureContainer(ContainerBuilder containerBuilder)
{
containerBuilder
.RegisterModule(new PersistenceModule(Configuration.GetConnectionString("DefaultConnection")));
containerBuilder
.RegisterModule(new DomainModule());
containerBuilder
.RegisterModule(new MediatRModule());
containerBuilder
.RegisterModule(new CommandsModule());
containerBuilder
.RegisterModule(new QueriesModule());
}

You cannot have dependencies in your Module constructor. But you can provide a value for a parameter by resolving it from the container:
builder.RegisterType<SqlConnectionFactory>()
.As<ISqlConnectionFactory>()
.WithParameter(
// match parameter
(info, context) => info.Name == "connectionString",
// resolve value
(info, context) =>
{
var config = context.Resolve<Microsoft.Extensions.Configuration.IConfiguration>();
return config.GetConnectionString("DefaultConnection");
}
);
References
https://autofac.readthedocs.io/en/latest/register/parameters.html?highlight=withparameter#parameters-with-reflection-components

If the module takes a constructor parameter you can't auto-register it. You have to provide the value in a registration directly.

How to Inject EF DbContext in Wpf using caliburn micro

I try to build WPF application to interact with database through Repositories above Entity framework, and I use caliburn micro as MVVM framework
the problem is when I try to inject Repertories in ViewModels Through Simple Container it does not instantiate My DbContext
Repository
public class UserRepo : IUserRepo
{
private AppDb _ctx;
public UserRepo(AppDb ctx)
{
_ctx = ctx;
}
}
application context
public class AppDb : DbContext
{
public AppDb(DbContextOptions options) : base(options)
{
}
public DbSet<User> Users { get; set; }
}
configuration on Simple Container
class Bootstrapper : BootstrapperBase
{
private SimpleContainer _container = new SimpleContainer();
private AppDb _db;
public Bootstrapper()
{
Initialize();
var options = new DbContextOptionsBuilder<AppDb>()
.UseSqlServer(#"Server=(localdb)\MSSQLLocalDB;Database=XRaySystem;Integrated Security=True;")
.Options;
_db = new AppDb(options);
}
protected override void Configure()
{
_container.Instance(_container);
_container
.Singleton<IWindowManager, WindowManager>()
.Singleton<IEventAggregator, EventAggregator>();
//register the DataContext
// i don't know how to add it
_container.RegisterInstance(typeof(AppDb), null, _db); // <<<<<<<<<< how to add this correctly
//Register Reporisotries
_container
.PerRequest<IUserRepo, UserRepo>();
//Register ViewModels
GetType().Assembly.GetTypes()
.Where(type => type.IsClass)
.Where(type => type.Name.EndsWith("ViewModel"))
.ToList()
.ForEach(viewModelType => _container.RegisterPerRequest(
viewModelType, viewModelType.ToString(), viewModelType));
}
protected override void OnStartup(object sender, StartupEventArgs e)
{
DisplayRootViewFor<DashBoardViewModel>();
//base.OnStartup(sender, e);
}
protected override object GetInstance(Type service, string key)
{
return _container.GetInstance(service, key);
}
protected override IEnumerable<object> GetAllInstances(Type service)
{
return _container.GetAllInstances(service);
}
protected override void BuildUp(object instance)
{
_container.BuildUp(instance);
}
}
View model
class DoctorViewModel : Screen
{
private readonly IUserRepo _userRepo;
public DoctorViewModel(IUserRepo userRepo)
{
_userRepo = userRepo;
}
}
UserRepo is instantiated but with null AppDb
my Question
How to configure Simple Container to Add AppDb to UserRepo?
I have reproduced the same problem in on GitHub

After some debugging, I found that Configure Method run first then the constructor call !! So the instantiation is happened after the Configuration already done with null
I solve it by adding the instantiation of _db in Configure method itself
class Bootstrapper : BootstrapperBase
{
private SimpleContainer _container = new SimpleContainer();
private AppDb _db;
public Bootstrapper()
{
Initialize();
}
protected override void Configure()
{
var options = new DbContextOptionsBuilder<AppDb>()
.UseSqlServer(#"Server=(localdb)\MSSQLLocalDB;Database=XRaySystem;Integrated Security=True;")
.Options;
_db = new AppDb(options); //<<<< solve the problem
_container.Instance(_container);
_container
.Singleton<IWindowManager, WindowManager>()
.Singleton<IEventAggregator, EventAggregator>();
//register the DataContext
_container.Instance(_db);
// _container.RegisterInstance(typeof(AppDb), null, _db);
//Register Reporisotries
_container
.PerRequest<IUserRepo, UserRepo>();
//Register ViewModels
GetType().Assembly.GetTypes()
.Where(type => type.IsClass)
.Where(type => type.Name.EndsWith("ViewModel"))
.ToList()
.ForEach(viewModelType => _container.RegisterPerRequest(
viewModelType, viewModelType.ToString(), viewModelType));
}
protected override void OnStartup(object sender, StartupEventArgs e)
{
DisplayRootViewFor<DashBoardViewModel>();
//base.OnStartup(sender, e);
}
protected override object GetInstance(Type service, string key)
{
return _container.GetInstance(service, key);
}
protected override IEnumerable<object> GetAllInstances(Type service)
{
return _container.GetAllInstances(service);
}
protected override void BuildUp(object instance)
{
_container.BuildUp(instance);
}
}

Autofac Property Injection in Nancy Module

I am using Autofac for DI and i have NacyModule like:
public class TestModule: NancyModule
{
public ISessionFactory SessionFactory { get; set; }
public IMapper Mapper { get; set; }
public TestModule(ITestRepository testRepository)
{
Get("hello", _ => "hello world");
}
}
My AutoFac configuration
In Startup.cs
var builder = new ContainerBuilder();
builder.RegisterModule(new ServicesModule());
builder.RegisterModule(new NHibernateModule(configuration.GetConnectionString("DefaultConnection")));
builder.RegisterModule(new AutomapperModule());
builder.Populate(services);
container = builder.Build();
return new AutofacServiceProvider(container);
in ServiceModule.cs
builder.RegisterAssemblyTypes(ThisAssembly)
.Where(t => new[]
{
"Processor",
"Process",
"Checker",
"Indexer",
"Searcher",
"Translator",
"Mapper",
"Exporter",
"Repository" }.Any(y =>
{
var a = t.Name;
return a.EndsWith(y);
}))
.AsSelf()
.AsImplementedInterfaces()
.PropertiesAutowired()
.InstancePerLifetimeScope();
in NHibernateModule.cs
builder.Register(c => CreateConfiguration(connectionString)).SingleInstance();
builder.Register(c => c.Resolve<Configuration>().BuildSessionFactory()).As<ISessionFactory>().SingleInstance().PropertiesAutowired();
And in my nancy bootstraper I have something like this
public class Bootstrapper : AutofacNancyBootstrapper
{
private static readonly ILogger logger = LogManager.GetLogger(typeof(Bootstrapper).FullName);
private readonly ILifetimeScope _container;
public Bootstrapper(ILifetimeScope container)
{
_container = container;
}
protected override ILifetimeScope GetApplicationContainer()
{
return _container;
}
public override void Configure(INancyEnvironment environment)
{
base.Configure(environment);
environment.Tracing(false, true);
}
protected override void ConfigureRequestContainer(ILifetimeScope container, NancyContext context)
{
container.Update(builder =>
{
builder.Register(c =>
{
var sf = c.Resolve<ISessionFactory>();
return new Lazy<NHibernate.ISession>(() =>
{
var s = sf.OpenSession();
s.BeginTransaction();
return s;
});
}).InstancePerLifetimeScope();
builder.Register(c => c.Resolve<Lazy<NHibernate.ISession>>().Value).As<NHibernate.ISession>();
});
}
}
I now about constructor injection, works ok, and property injection works ok in other classes, but not works in nancy modules
Note I tried adding .PropertiesAutowired() in ConfigureRequestContainer after the container update
thanks.

The AutofacNancyBootstrapper class automatically register the module in Autofac even if the service is already registered :
AutofacNancyBootstrapper.cs
protected override INancyModule GetModule(ILifetimeScope container, Type moduleType)
{
return container.Update(builder => builder.RegisterType(moduleType)
.As<INancyModule>())
.Resolve<INancyModule>();
}
With the default implementation the module is always registered and PropertiesAutoWired is not applied.
To change this, you can override the method like this :
protected override INancyModule GetModule(ILifetimeScope container, Type moduleType)
{
return container.Update(builder => builder.RegisterType(moduleType)
.As<INancyModule>())
.Resolve<INancyModule>()
.PropertiesAutoWired();
}
Or change it like this :
protected override INancyModule GetModule(ILifetimeScope container, Type moduleType)
{
INancyModule module = null;
if (container.IsRegistered(moduleType))
{
module = container.Resolve(moduleType) as INancyModule;
}
else
{
IEnumerable<IComponentRegistration> registrations = container.ComponentRegistry.RegistrationsFor(new TypedService(typeof(INancyModule)));
IComponentRegistration registration = registrations.FirstOrDefault(r => r.Activator.LimitType == moduleType);
if (registration != null)
{
module = container.ResolveComponent(registration, Enumerable.Empty<Parameter>()) as INancyModule;
}
else
{
module = base.GetModule(container, moduleType);
}
}
return module;
}
and then register the module in your composition root
builder.RegisterType<TestModule>()
.As<INancyModule>()
.PropertiesAutoWired()

Register different assembly types in autofac container in Asp.net

I have 3 tier architecture application. my Data Access is like below:
ICategoryRepository.cs
public interface ICategoryRepository
{
void Add(Category category);
}
CategoryRepository.cs
internal class CategoryRepository : ICategoryRepository
{
void ICategoryRepository.Add(Category category)
{
// Dbcontext goes here
}
}
And I have a Autofac model to register the above classes in autofac container is:
public class RepositoryModule : Module
{
protected override void Load(ContainerBuilder builder)
{
var assembly = System.Reflection.Assembly.GetExecutingAssembly();
builder.RegisterAssemblyTypes(assembly)
.Where(t => t.Name.EndsWith("Repository"))
.AsImplementedInterfaces();
base.Load(builder);
}
}
And I have a service layer as below:
ICategoryService.cs
public interface ICategoryService
{
void Add(Category category);
}
CategoryService.cs
internal class CategoryService : ICategoryService
{
private ICategoryRepository _categoryRepository;
public CategoryService(ICategoryRepository categoryRepository)
{
_categoryRespoitory = categoryRepository;
}
void ICategoryService.Add(Category category)
{
_categoryRepository.Add(category);
}
}
Similarly, I have a module to register the above class in container as,
public class ServiceModule : Autofac.Module
{
protected override void Load(ContainerBuilder builder)
{
var assembly = System.Reflection.Assembly.GetExecutingAssembly();
builder.RegisterAssemblyTypes(assembly)
.Where(t => t.Name.EndsWith("Service"))
.AsImplementedInterfaces()
.InstancePerLifetimeScope();
}
}
And in my Web, Global.asax.cs:
public class Global : System.Web.HttpApplication, IContainerProviderAccessor
{
static IContainerProvider _containerProvider;
public IContainerProvider ContainerProvider
{
get { return _containerProvider; }
}
void Application_Start(object sender, EventArgs e)
{
var builder = new ContainerBuilder();
var assembly = System.Reflection.Assembly.GetExecutingAssembly();
_containerProvider = new ContainerProvider(builder.Build());
}
}
Here my question is, how can I call the service and DataAccess module from the web.
I don't have the data access reference in my web, but I have reference of service module in my web

You can use the RegisterAssemblyModules method
void Application_Start(object sender, EventArgs e)
{
var builder = new ContainerBuilder();
IEnumerable<Assembly> assemblies = AppDomain.CurrentDomain.GetAssemblies();
if (HostingEnvironment.InClientBuildManager)
{
assemblies = assemblies.Union(BuildManager.GetReferencedAssemblies()
.Cast<Assembly>())
.Distinct();
}
builder.RegisterAssemblyModules(assemblies);
_containerProvider = new ContainerProvider(builder.Build());
}
In order to let this code works, all your assemblies should be available on the bin folder.
I use BuildManager.GetReferencedAssemblies() to avoid issue after ASP.net recycling process. See IIS Hosted Web Application on autofac documentation for more explanation.