Exception:
Nullreference exception
Here is my Code:
Controller:
private IUserService UserService;
public HomeController()
{
}
public HomeController(IUserService UserService)
{
this.UserService = UserService;
}
[HttpPost]
public ActionResult Register(RegisterViewModel reg)
{
SADM_Users users = new SADM_Users();
if (reg == null)
{
return Json(false);
}
else
{
FillUserMaster(users, reg);
UserService.insertUser(users);
ViewBag.ErrorMsg = "Succesfully added";
}
return View();
}
Service Layer:
public interface IUserService
{
void insertUser(SADM_Users users);
}
public class UserService:IUserService
{
private readonly ILoginRepository LoginRepository;
private readonly IUnitOfWork unitOfWork;
public UserService(ILoginRepository LoginRepository)
{
this.LoginRepository = LoginRepository;
}
public void insertUser(SADM_Users users)
{
try
{
LoginRepository.Add(users);
unitOfWork.Commit();
}
finally {
users = null;
}
}
}
I'm creating an mvc app with a service layer. I'm used to call services using in my controllers, but these services have not been Called.
please some one help on this.and i wnt to know any dependancy factor.
Remove the default constructor from your HomeController and make sure that you are using a DI library that will inject the proper implementation of IUserService into it.
Related
I'm creating a custom model binder for a view model, implementing IModelBinder
I have a lot of properties in my view model, the majority of which do not need any custom binding. Rather than explicitly set all of the property values on my model individually from the ModelBindingContext, I would to be able to get the framework to bind the model for me, then I would carry out any custom binding:
public class ApplicationViewModelBinder : IModelBinder
{
public Task BindModelAsync(ModelBindingContext bindingContext)
{
if (bindingContext == null)
{
throw new ArgumentNullException(nameof(bindingContext));
}
// get .net core to bind values on model
// Cary out any customization of the models properties
bindingContext.Result = ModelBindingResult.Success(bindingContext.Model);
return Task.CompletedTask;
}
}
Basically I want to carry out the default model binding, then apply custom binding, similar to the approach taken in this SO post but for .NET Core, not framework.
I assumed applying the default binding would be straight forward, but haven't been able to find out how to do so. I believe the solution would involve ComplexTypeModelBinder and ComplexTypeModelBinderProvider classes, but can't seem to find out how to go about it.
I know I could just make any changes when the POST request hits my controller method, but this seem the wrong place and wrong time to do so.
For custom ComplexTypeModelBinder, you could inherit from ComplexTypeModelBinder.
Model
public class BinderModel
{
public int Id { get; set; }
public string Name { get; set; }
public string BinderValue { get; set; }
}
Controller Action
[HttpPost]
public void Post([FromForm]BinderModel value)
{
}
CustomBinder
public class CustomBinder : ComplexTypeModelBinder
{
private readonly IDictionary<ModelMetadata, IModelBinder> _propertyBinders;
public CustomBinder(IDictionary<ModelMetadata, IModelBinder> propertyBinders)
: base(propertyBinders)
{
_propertyBinders = propertyBinders;
}
protected override Task BindProperty(ModelBindingContext bindingContext)
{
if (bindingContext.FieldName == "BinderValue")
{
bindingContext.Result = ModelBindingResult.Success("BinderValueTest");
return Task.CompletedTask;
}
else
{
return base.BindProperty(bindingContext);
}
}
protected override void SetProperty(ModelBindingContext bindingContext, string modelName, ModelMetadata propertyMetadata, ModelBindingResult result)
{
base.SetProperty(bindingContext, modelName, propertyMetadata, result);
}
}
CustomBinderProvider
public class CustomBinderProvider : IModelBinderProvider
{
public IModelBinder GetBinder(ModelBinderProviderContext context)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (context.Metadata.IsComplexType && !context.Metadata.IsCollectionType)
{
var propertyBinders = new Dictionary<ModelMetadata, IModelBinder>();
for (var i = 0; i < context.Metadata.Properties.Count; i++)
{
var property = context.Metadata.Properties[i];
propertyBinders.Add(property, context.CreateBinder(property));
}
//var loggerFactory = context.Services.GetRequiredService<ILoggerFactory>();
//return new ComplexTypeModelBinder(propertyBinders, loggerFactory);
return new CustomBinder(propertyBinders);
}
return null;
}
}
Inject provider
public void ConfigureServices(IServiceCollection services)
{
services.AddMvc(options => {
options.ModelBinderProviders.Insert(0, new CustomBinderProvider());
});
}
ComplexTypeModelBinder has unfortunately been deprecated in .Net 5.0, and it's counterpart, ComplexObjectModelBinder, is sealed, so you can't extend from it.
But, you can work around that. ComplexObjectModelBinderProvider is public, and you can use that to create a ComplexObjectModelBinder. Thus, if you make your own custom IModelBinderProvider, you can have the constructor accept a ComplexObjectModelBinderProvider argument, and make use of that to make a ComplexObjectModelBinder. Then, you can pass that to your custom IModelBinder, where it'll happily do its custom work before falling back to the ComplexObjectModelBinder you supplied.
Here's an example. First, your IModelBinder. This example shows that you can use DI if you want to. (In this example, say we needed a DbContext.)
public class MyCustomModelBinder : IModelBinder
{
private readonly IModelBinder _defaultBinder;
private readonly DbContext _dbContext;
public MyCustomModelBinder(IModelBinder defaultBinder, DbContext dbContext)
{
_defaultBinder = defaultBinder;
_dbContext = dbContext;
}
public override Task BindModelAsync(ModelBindingContext bindingContext)
{
// -do custom work here-
return _defaultBinder.BindModelAsync(bindingContext);
}
}
However, in order to use DI on your custom model binder, you'll need a helper class. The problem is, when IModelBinderProvider is called, it won't have access to all the services in a typical request, like your DbContext for example. But this class will help:
internal class DIModelBinder : IModelBinder
{
private readonly IModelBinder _rootBinder;
private readonly ObjectFactory _factory;
public DIModelBinder(Type binderType, IModelBinder rootBinder)
{
if (!typeof(IModelBinder).IsAssignableFrom(binderType))
{
throw new ArgumentException($"Your binderType must derive from IModelBinder.");
}
_factory = ActivatorUtilities.CreateFactory(binderType, new[] { typeof(IModelBinder) });
_rootBinder = rootBinder;
}
public Task BindModelAsync(ModelBindingContext bindingContext)
{
var requestServices = bindingContext.HttpContext.RequestServices;
var binder = (IModelBinder)_factory(requestServices, new[] { _rootBinder });
return binder.BindModelAsync(bindingContext);
}
}
Now you're ready to write the custom IModelBinderProvider:
public class MyCustomModelBinderProvider : IModelBinderProvider
{
private readonly IModelBinderProvider _rootProvider;
public MyCustomModelBinderProvider(IModelBinderProvider rootProvider)
{
_rootProvider = rootProvider;
}
public IModelBinder? GetBinder(ModelBinderProviderContext context)
{
if (context.Metadata.ModelType == typeof(MyModel))
{
var rootBinder = _rootProvider.GetBinder(context)
?? throw new InvalidOperationException($"Root {_rootProvider.GetType()} did not provide an IModelBinder for MyModel.");
return new DIModelBinder(typeof(MyCustomModelBinder), rootBinder);
}
return null;
}
}
Finally, in your startup file where you configure services, you can grab the ComplexObjectModelBinderProvider instance, use that to create a new instance of your MyCustomModelBinderProvider, and insert that into the ModelBinderProviders.
services.AddMvc(options =>
{
var fallbackProvider = options.ModelBinderProviders
.First(p => p is ComplexObjectModelBinderProvider);
var myProvider = new MyCustomModelBinderProvider(fallbackProvider);
options.ModelBinderProviders.Insert(0, myProvider);
})
I want to inject unity container into WebController.
I have UnityDependencyResolver:
public class UnityDependencyResolver : IDependencyResolver
{
readonly IUnityContainer _container;
public UnityDependencyResolver(IUnityContainer container)
{
this._container = container;
}
public object GetService(Type serviceType)
{
try
{
return _container.Resolve(serviceType);
}
catch
{
return null;
}
}
public IEnumerable<object> GetServices(Type serviceType)
{
try
{
return _container.ResolveAll(serviceType);
}
catch
{
return new List<object>();
}
}
public void Dispose()
{
_container.Dispose();
}
}
Then, in my Global.asax I add the following line:
var container = new UnityContainer();
container.RegisterType<IService, Service>
(new PerThreadLifetimeManager()).RegisterType<IDALContext, DALContext>();
DependencyResolver.SetResolver(new UnityDependencyResolver(container));
Then, If I use the following in a Web Controller:
private IService _service;
public HomeController(IService srv)
{
_service = srv;
}
It works fine.
But I want to inject it into WebAPI Controller, so if I do it the same way:
private IService _service;
public ValuesController(IService srv)
{
_service = srv;
}
It does not work, it says that constructor is not defined.
Ok, I create one more constructor:
public ValuesController(){}
And in this case it uses only this constructor and never the one where I should inject unity container.
Please advise.
Add this in your WebApiConfig:
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
// Routes and other stuff here...
var container = IocContainer.Instance; // Or any other way to fetch your container.
config.DependencyResolver = new UnityDependencyResolver(container);
}
}
And if you want the same container you can keep it in a static variable, like so:
public static class IocContainer
{
private static readonly Lazy<IUnityContainer> Container = new Lazy<IUnityContainer>(() =>
{
var container = new UnityContainer();
return container;
});
public static IUnityContainer Instance
{
get { return Container.Value; }
}
}
More info can be found here:
http://www.asp.net/web-api/overview/advanced/dependency-injection
On a sidenote, I can also recommend the nuget-package Unity.Mvc. It adds a UnityWebActivator and support for PerRequestLifetimeManager.
https://www.nuget.org/packages/Unity.Mvc/
A bit of history first. I created a EF Code First Library that contains POCO Objects as my Models, a generic DataProvider that inherits from DbContext, generic Repostory that implements the generic DataProvider, and a generic Service that implements the repository. I have used this library successfully in WPF (MVVM), ASP.Net, Window Forms, and ASP MVC applications.
For this discussion I will reference the Company Model
From the top down, I create a Service class called CompanyService that inherits from a base Service Class. The CompanyService class contains all of the business logic for the Company Model. This class uses the Repository class to perform the CRUD operations. The Repository then encapsulates all the DataProvider class operations.
I have done some research on using EF with WCFDataService, but I can't get my head around how to implement my library with it, particulary when it comes to overriding the CreateDataSource() Method.
It may be that I should just use a WCF Service instead, maybe I'm not understanding the purpose of the WCFDataService.
I have listed partial code for the classes involved:
public class CompanyService : ServiceBase<Company> ,ICompanyService
{
public Company GetCompanyByFolderId(string eFolderId)
{
return (Company)GetModelByFolderId(eFolderId);
}
}
public abstract class ServiceBase<TModel> : IService<TModel> where TModel : class, IModel
{
private IDataProvider _dataProvider;
public IDataProvider DataProvider
{
get
{
if (_dataProvider == null)
{
string connectionStringName = Properties.Settings.Default.DataProvider;
bool enableLazyLoading = true;
_dataProvider = new DataProvider(connectionStringName, enableLazyLoading);
}
return _dataProvider;
}
set
{
_dataProvider = value;
}
}
private IRepository<TModel> _repository;
public IRepository<TModel> Repository
{
get
{
if (_repository == null)
{
_repository = new Repository<TModel>(DataProvider);
}
return _repository;
}
set
{
_repository = value;
}
}
public TModel GetModelByFolderId(String folderId)
{
return GetTable().FirstOrDefault(o => o.EFolderid == folderId);
}
public virtual IQueryable<TModel> GetTable()
{
return Repository.GetTable();
}
}
public class Repository<TModel> : IRepository<TModel> where TModel : class, IModel
{
private IDataProvider _dataProvider;
public Repository(IDataProvider dataProvider)
{
_dataProvider = dataProvider;
}
private IDbSet<TModel> DbSet
{
get
{
return _dataProvider.Set<TModel>();
}
}
public IQueryable<TModel> GetTable()
{
return _dataProvider.GetTable<TModel>();
}
}
public class DataProvider : DbContext, IDataProvider
{
public DataProvider()
{
}
public DataProvider(string connectionStringName, bool enableLazyLoading = true)
: base(connectionStringName)
{
Configuration.LazyLoadingEnabled = enableLazyLoading;
//Configuration.ProxyCreationEnabled = false;
}
public new IDbSet<TModel> Set<TModel>() where TModel : class
{
return base.Set<TModel>();
}
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Configurations.Add(new CompanyMapping());
base.OnModelCreating(modelBuilder);
}
public IQueryable<TModel> GetTable<TModel>() where TModel : class
{
return Set<TModel>().AsQueryable();
}
}
Then my Test looks something like this:
[TestClass()]
public class CompanyServiceTest
{
[TestMethod()]
public void GetCompanies()
{
CompanyService target = new CompanyService();
IQueryable<Company> companies = target.GetTable();
Assert.IsNotNull(companies);
}
[TestMethod()]
public void GetCompanyByFolderId()
{
CompanyService target = new CompanyService();
Company company = target.GetCompanyByFolderId("0000000000000000000000000172403");
Assert.IsNotNull(company);
}
}
I am developing a (hopefully) RESTful API using ServiceStack.
I noticed that most of my services look the same, for example, a GET method will look something like this:
try
{
Validate();
GetData();
return Response();
}
catch (Exception)
{
//TODO: Log the exception
throw; //rethrow
}
lets say I got 20 resources, 20 request DTOs, so I got about 20 services of the same template more or less...
I tried to make a generic or abstract Service so I can create inheriting services which just implement the relevant behavior but I got stuck because the request DTOs weren't as needed for serialization.
Is there any way to do it?
EDIT:
an Example for what I'm trying to do:
public abstract class MyService<TResponse,TRequest> : Service
{
protected abstract TResponse InnerGet();
protected abstract void InnerDelete();
public TResponse Get(TRequest request)
{
//General Code Here.
TResponse response = InnerGet();
//General Code Here.
return response;
}
public void Delete(TRequest request)
{
//General Code Here.
InnerDelete();
//General Code Here.
}
}
public class AccountService : MyService<Accounts, Account>
{
protected override Accounts InnerGet()
{
throw new NotImplementedException();//Get the data from BL
}
protected override void InnerDelete()
{
throw new NotImplementedException();
}
}
To do this in the New API we've introduced the concept of a IServiceRunner that decouples the execution of your service from the implementation of it.
To add your own Service Hooks you just need to override the default Service Runner in your AppHost from its default implementation:
public virtual IServiceRunner<TRequest> CreateServiceRunner<TRequest>(ActionContext actionContext)
{
return new ServiceRunner<TRequest>(this, actionContext); //Cached per Service Action
}
With your own:
public override IServiceRunner<TRequest> CreateServiceRunner<TRequest>(ActionContext actionContext)
{
return new MyServiceRunner<TRequest>(this, actionContext); //Cached per Service Action
}
Where MyServiceRunner is just a custom class implementing the custom hooks you're interested in, e.g:
public class MyServiceRunner<T> : ServiceRunner<T> {
public override void OnBeforeExecute(IRequestContext requestContext, TRequest request) {
// Called just before any Action is executed
}
public override object OnAfterExecute(IRequestContext requestContext, object response) {
// Called just after any Action is executed, you can modify the response returned here as well
}
public override object HandleException(IRequestContext requestContext, TRequest request, Exception ex) {
// Called whenever an exception is thrown in your Services Action
}
}
Also for more fine-grained Error Handling options check out the Error Handling wiki page.
My solution was to add an additional layer where I can handle Logic per entity:
Base Logic Sample:
public interface IEntity
{
long Id { get; set; }
}
public interface IReadOnlyLogic<Entity> where Entity : class, IEntity
{
List<Entity> GetAll();
Entity GetById(long Id);
}
public abstract class ReadOnlyLogic<Entity> : IReadOnlyLogic<Entity> where Entity : class, IEntity, new()
{
public IDbConnection Db { get; set; }
#region HOOKS
protected SqlExpression<Entity> OnGetList(SqlExpression<Entity> query) { return query; }
protected SqlExpression<Entity> OnGetSingle(SqlExpression<Entity> query) { return OnGetList(query); }
#endregion
public List<Entity> GetAll()
{
var query = OnGetList(Db.From<Entity>());
return Db.Select(query);
}
public Entity GetById(long id)
{
var query = OnGetSingle(Db.From<Entity>())
.Where(e => e.Id == id);
var entity = Db.Single(query);
return entity;
}
}
Then we can use hooks like:
public interface IHello : IReadOnlyLogic<Hello> { }
public class HelloLogic : ReadOnlyLogic<Hello>, IHello
{
protected override SqlExpression<Hello> OnGetList(SqlExpression<Hello> query)
{
return query.Where(h => h.Name == "Something");
}
}
Finally our service only calls our logic:
public class MyServices : Service
{
IHello helloLogic;
public object Get()
{
return helloLogic.GetAll();
}
}
I want to have my own AppContext in my ApiController (MVC4).
Should be something like
public class TestController : BaseApiController
{
[HttpGet]
public IEnumerable<TestVM> GetAll()
{
// the test service is injected with SimpleInjector
return _testService.GetAll(**base.AppContext**);
}
}
but the ApiController haven't access to the Session.
Are there any solutions to "activate" the Session for specific keys (because I don't want the whole Session)?
Or do you have any other idea (cache or cookie)?
This is the BaseApiController
public abstract class BaseApiController: ApiController
{
public IAppContext AppContext
{
get { return SessionState.AppContext; }
}
}
and this is my IAppContext (it will have more properties in the future)
public interface IAppContext
{
IIdentity User { get; }
/// <summary> Gets the user id. </summary>
/// <value>The user id.</value>
int IdUser { get; }
}
here the application module which is registered in the web.config
public class ApplicationModule : IHttpModule
{
// ...
SessionState.AppContext = _appContext.InitializeNew(
HttpRuntime.AppDomainAppPath, languages);
// ...
}
SessionState class to get the AppContext
public class SessionState : BaseSessionVariables
{
public static IAppContext AppContext
{
get { return SessionState.Get<IAppContext>("AppContext"); }
set { SessionState.Set("AppContext", value); }
}
}
here the BaseSessionVariables class
public static HttpSessionState GetSession()
{
return HttpContext.Current.Session;
}
protected static T Get<T>(string key) where T : class
{
var session = BaseSessionVariables.GetSession();
if (session == null)
{
throw new Exception("No session");
}
return (session[key] as T);
}
Thanks for your help!
Take a look at the implementation below. It should get you headed in the right direction.
Updated IAppContext - Added Setters
public interface IAppContext
{
IIdentity User { get; set; }
/// <summary> Gets the user id. </summary>
/// <value>The user id.</value>
int IdUser { get; set; }
}
Updated Base Controller - Instantiates a new AppContextImplemenation in the OnActionExecuting method
public abstract class BaseApiController: ApiController
{
public IAppContext AppContext {get; set;}
protected override void OnActionExecuting(
ActionExecutingContext filterContext)
{
AppContext = new AppContextImplementation();
}
}
New Class - implements IAppContext and wraps the HttpContext Session. For testing you can then create an TestAppContextImplementation that doesn't rely on Session but some other in memory storage mechanism.
public class AppContextImplementation : IAppContext
{
public IIdentity User
{
get { return HttpContext.Current.Session["User"] as IIdentity; }
set { HttpContext.Current.Session["User"] = value; }
}
int IdUser
{
get { return Convert.ToInt32(Session["IdUser"]); }
set { Session["IdUser"] = value; }
}
}
For ApiControllers, build yourself a DelegatingHandler and push all of your goodies onto request.Properties. You can then retrieve them from your request whether you are testing or running live. The benefit is that you then have zero dependency on Session in your Controller.
MessageHandler
public class ContextHandler : DelegatingHandler
{
protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, System.Threading.CancellationToken cancellationToken)
{
// get the goodies to add onto the request
var goodies = /* call to goodieGoodieYumYum */
// add our goodies onto the request
request.Properties.Add(Constants.RequestKey_Goodies, goodies);
// pass along to the next handler
return base.SendAsync(request, cancellationToken);
}
}
Controller Action
var goodies = (List<Goodie>)Request.Properties[Constants.RequestKey_Goodies];