We are building a multi-tenant database application utilizing ASP.NET MVC, the Entity Framework Code First, and the soon to be released SQL Azure Federations. Our repository accepts a DbContext as a constructor argument that is injected using Ninject. The problem is that the DbContext has an int constructor argument to specify the account id that will be used for the requests made with that context. Something like this:
public class DatabaseContext : DbContext
{
public DatabaseContext(int accountId)
{
// Code here to ensure we only work with data associated with
// the account identified by accountId
}
}
The value for the account id will be stored in a Session variable. The question is how do we get Ninject to inject a value from Session into the constructor when it creates a new instance of DatabaseContext?
Or is there another way I should go about injecting the account id into the DbContext?
There are a few ways. I like using the .ToMethod approach.
Bind<DatabaseContext>().ToMethod(
c => new DatabaseContext((int)HttpContext.Current.Session["Acct"]);
Though to solve this particular problem, I've found it better to create an ISessionManager service that has session-based data on it. Anything that wants, e.g., an accountId would have this service injected into the constructor, and access its AccountId property when it needs an account ID.
Related
I'm trying to get details about the current user in my DBContext so that I can store a CreatedByUserId and ModifiedByUserId when a record is updated.
What I'm finding is that the IPrincipal instance injected is valid for the controllers, but is null when injected into my DB Context, which is in a separate assembly.
I'm doing the injection with Autofac as follows:
builder.Register(c => HttpContext.Current.User).As<IPrincipal>().InstancePerRequest();
builder.Register<AppDbContext>(c => new AppDbContext(GlobalHost.DependencyResolver.Resolve<IPrincipal>())).InstancePerLifetimeScope();
My controller constructors look like this, and user will be valid here as expected:
public class ProductsController : Controller
{
private readonly IProductService _productService;
public ProductsController(IProductService productService, IPrincipal userPrincipal)
{
var user = userPrincipal;
_productService = productService;
}
My DBContext constructor looks like this and user will be null here:
public partial class AppDbContext : System.Data.Entity.DbContext, IAppDbContext
{
public AppDbContext(IPrincipal principal)
: this("Name=SqlConnection", principal)
{
var user = principal;
}
The controller code is called before the DB Context code, so it's not a timing issue, so I'm guessing the issue here is that the DB Context code is running on a different thread to the controller with different identity maybe?
If I use this code to get the identity in my DB context I can successfully get the user:
var user = System.Threading.Thread.CurrentPrincipal;
But it seems like I might run into issues getting the user in two different ways in the same app, and I'd need to figure out a way to make the DI return HTTPContext's user to the web project and the thread's principal to another assembly, all of which smacks of being the wrong solution?
Can anyone help me understand exactly why I'm seeing the behaviour above and advise on the best way to get the principal in the different assemblies of an mvc app?
So, the issue here turns out to be that I'm using the wrong Dependency Resolver when setting up the DB Context in this line:
builder.Register<AppDbContext>(c => new AppDbContext(GlobalHost.DependencyResolver.Resolve<IPrincipal>())).InstancePerLifetimeScope();
GlobalHost.DependencyResolver is giving me the SignalR resolver rather than MVC's resolver. Removing the GlobalHost bit then gives me the System.Web.MVC.DependencyResolver instead and then I can use that to get the IPrincipal as follows:
builder.Register<AppDbContext>(c => new AppDbContext(DependencyResolver.Current.GetService<IPrincipal>())).InstancePerRequest();
I'm trying to use NHibernate for a new app with a legacy database. It's going pretty well but I'm stuck and can't find a good solution for a problem.
Let's say I have this model :
a Service table (Id, ServiceName..)
a Movie table (Id, Title, ...)
a Contents table which associates a service and a movie (IdContent, Name, IdMovie, IdService)
So I mapped this and it all went good. Now I can retrieve a movie, get all the contents associated, ...
My app is a movies shop "generator". Each "service" is in fact a different shop, when a user enter my website, he's redirected to one of the shops and obviously, I must show him only movies available for his shop. The idea is : user comes, his service is recognized, I present him movies which have contents linked to his service. I need to be able to retrieve all contents for a movie for the backoffice too.
I'm trying to find the most transparent way to accomplish this with NHibernate. I can't really make changes to the db model.
I thought about a few solutions :
Add the service condition into all my queries. Would work but it's a bit cumbersome. The model is very complex and has tons of tables/queries..
Use nhibernate filter. Seemed ideal and worked pretty good, I added the filter on serviceid in all my mappings and did the EnableFilter as soon as my user's service was recognized but.. nhibernate filtered collections don't work with 2nd lvl cache (redis in my case) and 2nd lvl cache usage is mandatory.
Add computed properties to my object like Movie.PublishedContents(Int32 serviceId). Probably would work but requires to write a lot of code and "pollutes" my domain.
Add new entities inheriting from my nhibernate entity like a PublishedMovie : Movie wich only presents the contextual data
None of these really satisfies me. Is there a good way to do this ?
Thanks !
You're asking about multi-tenancy with all the tenants in the same database. I've handled that scenario effectively using Ninject dependency injection. In my application the tenant is called "manual" and I'll use that in the sample code.
The route needs to contain the tenant e.g.
{manual}/{controller}/{action}/{id}
A constraint can be set on the tenant to limit the allowed tenants.
I use Ninject to configure and supply the ISessionFactory as a singleton and ISession in session-per-request strategy. This is encapsulated using Ninject Provider classes.
I do the filtering using lightweight repository classes, e.g.
public class ManualRepository
{
private readonly int _manualId;
private readonly ISession _session;
public ManualRepository(int manualId, ISession session)
{
_manualId = manualId;
_session = session;
}
public IQueryable<Manual> GetManual()
{
return _session.Query<Manual>().Where(m => m.ManualId == _manualId);
}
}
If you want pretty urls you'll need to translate the tenant route parameter into its corresponding database value. I have these set up in web.config and I load them into a dictionary at startup. An IRouteConstraint implementation reads the "manual" route value, looks it up, and sets the "manualId" route value.
Ninject can handle injecting the ISession into the repository and the repository into the controller. Any queries in the controller actions must be based on the repository method so that the filter is applied. The trick is injecting the manualId from the routing value. In NinjectWebCommon I have two methods to accomplish this:
private static int GetManualIdForRequest()
{
var httpContext = HttpContext.Current;
var routeValues = httpContext.Request.RequestContext.RouteData.Values;
if (routeValues.ContainsKey("manualId"))
{
return int.Parse(routeValues["manualId"].ToString());
}
const string msg = "Route does not contain 'manualId' required to construct object.";
throw new HttpException((int)HttpStatusCode.BadRequest, msg);
}
/// <summary>
/// Binding extension that injects the manualId from route data values to the ctor.
/// </summary>
private static void WithManualIdConstructor<T>(this IBindingWithSyntax<T> binding)
{
binding.WithConstructorArgument("manualId", context => GetManualIdForRequest());
}
And the repository bindings are declared to inject the manualId. There may be a better way to accomplish this through conventions.
kernel.Bind<ManualRepository>().ToSelf().WithManualIdConstructor();
The end result is that queries follow the pattern
var manual = _manualRepository
.GetManual()
.Where(m => m.EffectiveDate <= DateTime.Today)
.Select(m => new ManualView
{
ManualId = m.ManualId,
ManualName = m.Name
}).List();
and I don't need to worry about filtering per tenant in my queries.
As for the 2nd level cache, I don't use it in this app but my understanding is that you can set the cache region to segregate tenants. This should get you started: http://ayende.com/blog/1708/nhibernate-caching-the-secong-level-cache-space-is-shared
I am new to ServiceStack, so this is probably a noob question:
I am working on an ASP.NET MVC4 application that uses ServiceStack and am trying to figure out how I could get a hold of the current IAuthSession from within a class (either a EF context or a PetaPoco Database) used by my MVC4 controllers derived from ServiceStackController.
The class in question is registered with Funq with the ReuseScope.Request scope (i.e. on the per-HTTP request basis), and ideally I'd like every instance of it to be autowired with the current IAuthSession using either a constructor parameter or a public property.
How do I do that?
UPDATE
After some digging I came up with what I think might work.
In my AppHost.Configure I register a lambda that returns a session from the current request:
container.Register<IAuthSession>(c =>
HttpContext.Current.Request.ToRequest().GetSession());
Also:
container.RegisterAutoWired<EFCatalogDb>();
where EFCatalogDb is my EF context that takes IAuthSession as a constructor argument:
public class EFCatalogDb : DbContext
{
public EFCatalogDb(IAuthSession session) : base()
{ }
// ...etc....
}
Unfortunately I am not at the point in my development when I can test this workaround, so have to ask others if it makes sense at all.
My first suggestion would be to try to keep IAuthSession out of your database classes since that creates a dependency on ServiceStack that seems unnecessary.
That being said, I think you could go the route of registering IAuthSession and having the container automatically inject IAuthSession. A better way might be creating your own 'wrapper class' around IAuthSession and injecting that into your database classes. That would then break the dependency on ServiceStack.
If you have no issue keeping a dependency on ServiceStack another possibility would be using the SessionFeature class and doing something like
var key = SessionFeature.GetSessionKey();
authSession = AppHost.Resolve<ICacheClient>().Get<IAuthSession>(key);
I have a multitenant application in Asp.NET MVC with Ninject and Fluent nHibernate. I have one Database per tenant and I create one session factory for each tenant.
Now after the tenant logins, I need (if it doesn't exists) create a SessionFactory and get a session out of it. That's done.
My problem now is that the specific tenant info is extracted from the FormsAuth cookie and I need to pass it down layers...
Here are my layers :
Web
Service
Data
When my controllers need to access some info, they use the specific info service to get to the data repository with has a session which come from the sessionfactory.
In Data Layer :
Bind<SessionFactoryFactory>().ToSelf()
.InSingletonScope();
Bind<ISession>()
.ToMethod(ctx => ctx.Kernel.Get<SessionFactoryFactory>()
.Get(**[??TENANTINFOOBJECT??]**).OpenSession())
.WhenParentNamed("TenantDB")
.InRequestScope();
Bind<ISomeInfoRepository>()
.To<SomeInfoRepository>()
.InRequestScope()
.Named("TenantDB");
In Service Layer :
Bind<ISomeInfoService>().To<SomeInfoService>()
.InRequestScope();
In Web Layer :
public class SomeController : BaseController
{
ISomeInfoService someInfoService;
public SomeController(ISomeInfoService someInfoService)
{
this.someInfoService= someInfoService;
}...
How do I send to my sessionfactory the tenant info with Ninject? When a web request is made, I extract the tenant id from the cookie and can build the required tenant object (id + connection string). How do I pass it down the layers with Ninject to my SessionFactoryFactory?
Register a type that is your TenantInfo in the request scope. This TenantInfo could be created from the cookies using the ToMethod as you are doing in your question.
Then Bind the ISession to a ninject provider (a class which inherits from Provider). Make this provider take as a constructor argument (or property) the TenantInfo. Within the provider you then have the necessary information to construct your session. for the Tenant.
I am in the process of creating a custom membership provider for an ASP.Net MVC website. The provider is being created as a separate class as part of a bigger library. There is a need for the back-end data store to be flexible as it could be an Xml File or SQL database. My initial thought was to create an interface for the data store and inject this into provider using dependency injection.
The end result is required is that a developer can inherit the data store interface and provide the required methods to update the data, which will then be used by the custom membership providers.
However through my own lack of skill I can't figure out how to inject the class into the membership provider when adding it to the website? What needs to be done to link the data store to the provider? What would be the simplest way to enable this in the website?
If you are configuring the custom membership providers via the <membership> element in the Web.config file, then I can see the issues you will have with dependency injection.
The providers are constructed and managed by the framework, and there is no opportunity for you to intercept that construction to provide additional dependency injection for the IDataStore interface.
If my assumption is correct, then what you can do is override the Initialize() method in your custom provider, and do the dependency injection there. You can have a custom name/value setting in the provider configuration which points to a type that implements IDataStore, which is passed as part of a dictionary to the Initialize() method.
Then, you activate an instance of the data store type and set it on the appropriate property:
public class MyMembershipProvider : MembershipProvider
{
public IDataStore DataStore
{
get;
set;
}
public override Initialize(string name, NameValueCollection config)
{
var dataStoreType = config["dataStoreProvider"];
if (!String.IsNullOrEmpty(dataStoreType))
{
var type = Type.GetType(dataStoreType);
DataStore = (IDataStore) Activator.CreateInstance(type);
}
}
}
Initialize() will be called by the framework after it constructs an instance of your provider, so that is the perfect place to do any additional setup work such as this.
For testing scenarios, you just set the data store property on the provider instance itself, as you will be constructing it directly in your tests.
Isn't this better? I use it with MVC3 and ninject. It's enough to add a property to your custom membership provider class. Remember to add "using System.Web.Mvc;" on top.
public IRepository Repository
{
get
{
return DependencyResolver.Current.GetService<IRepository>();
}
}
The simplest way to do dependency injection that I've seen (and actually the only one I've used so far...) is to have a constructor of your dependent class take the interface as a parameter, and assign it to a private field. If you want, you can also add a "default" constructor, which chains to the first one with a default value.
Simplified, it would look something like this:
public class DependentClass
{
private IDataStore _store;
// Use this constructor when you want strict control of the implementation
public DependentClass(IDataStore store)
{
this._store = store;
}
// Use this constructor when you don't want to create an IDataStore instance
// manually every time you create a DependentClass instance
public DependentClass() : this(new DefaultDataStore()) { }
}
The concept is called "Constructor chaining", and there's a lot of articles on the web on how to do it. I find this tutorial very explanatory of the DI pattern.