I have a webapi2 C# projects on which I have all the controllers in a controllers folder.
I now have some functionality that I want to add but I want to put it on a different visual studio project that will have its own controllers (and models and views) folder. Is this possible so that I can create some kind of module that will be loaded by webapi2?
Web Api relies on the IHttpControllerSelector for choosing the api controller for handling a request, of which has a default implementation which relies on IAssembliesResolver for resolving the assemblies to search for the api controllers.
In the least minimum change, you can replace this assembly resolver with a custom implementation which will load other libraries for you.
A very naive example might look like the following:
public class CustomAssemblyResolver : IAssembliesResolver
{
public List<string> PluginNames { get; set; }
public CustomAssemblyResolver()
{
PluginNames = new List<string>();
//Add the custom libraries here
PluginNames.Add("Your_Second_Library");
}
public ICollection<Assembly> GetAssemblies()
{
var asms = AppDomain.CurrentDomain.GetAssemblies().ToList();
foreach (var name in PluginNames)
{
var asmPath = System.IO.Path.Combine(HostingEnvironment.MapPath("~/"), name + ".dll");
try
{
var asm= System.Reflection.Assembly.LoadFrom(asmPath);
if(!asms.Contains(asm))
asms.Add(asm);
}
catch (Exception)
{
}
}
return asms;
}
}
You can then replace the default resolver with this code
config.Services.Replace(typeof(IAssembliesResolver), new CustomAssemblyResolver());
inside your Register method of WebApiConfig class.
Then, copy all your additional libraries with controller classes to the bin directory and you are done.
If you need even further customization for controller selection, you can go for custom implementation of IHttpControllerSelector and replace the existing implementation in a similar fashion.
You can create the functionality in a library project, and then reference that project to the your webapi2 and your other visual studio project. Basically you will have three solutions; two webapi solutions and one library solution. The library solution will contain the required logic needed for the two webapi solutions.
You shouldn't have a need for controllers in two projects.
If the controllers are for COMPLETELY different business domains, make two api's in IIS w/ two solutions.
If they are similar, create all of your controllers in the web project. Then have these controllers call out to separate application services.
public CustomerAccountsController : ApiController
{
private CustomerAccountService _customerAccountService; // lives in application layer project
public CustomerAccountsController()
{
// di stuff
}
public HttpResponseMessage PutCancelAccount( int accountId )
{
// exception handling + logging
_customerAccountService.CancelAccount(accountId);
// return status code if success, or if an exception
}
}
public OrderController : ApiController
{
private OrderService _orderService; // lives in application layer project
public OrderController()
{ //di stuff
}
public HttpResponseMessage PostCreateOrder(CreateOrderRequest createOrderRequest)
{
// exception handling + logging
_orderService.TakeOrder(createOrderRequest);
// return status code if success, or if an exception
}
}
So, most of your logic should hide behind application layer services, and these services should have methods that map 1-1 to use cases. If your business domain for these two applications are completely different, just create two separate solutions and two separate IIS applications/api's
No, it is not possible. The maximum you can do is create a class library that will compile as a DLL, then reference that DLL in your WebApi. Otherwise, you will be obliged to either put everything in the same application (WebApi) or create two different WebApi applications.
Depending on your needs...
My advise, just put the 2 controllers on a single project and create a helper/service folder/class in your other project and call those services whenever you need.
This is not really the answer to your question but I believe this will help. Normally we create a solution using this folder structure, I hope this helps:
MyTeamSolution
- MyTeam.Core = Class libraries
> Models
> Model1.cs
> Model2.cs
> Model3.cs
> Interface
> ISomeInterface.cs
> Helpers
> HelperClass.cs
- MyTeam.Api = webapi project
> Model1Controller.cs
> Model2Controller.cs
> Model3Controller.cs
- MyTeam.Web = mvc project
> Controllers
> Models
> Views
> etc.
- MyTeam.Sql = Class libraries
> MyTeamDbContext.cs
Related
I have a Product.Core MVC project. This project has some common API controllers.
I have another MVC project "Product" that references Product.Core.
The API controllers work as expected. I can call APIs defined in both solutions.
I now want to extended one of the API controllers in Product.Core. Say XXXApiController.
I have the same controller defined in the Product project.
namespace Product
{
public class XXXApiController : Product.Core.XXXApiController
{
public new Task<XXXResponse> MyApiAsync()
{
var response = await base.MyApiAsync();
// do extra code here
return response;
}
}
}
However, after this change it seems the XXXApiController is no longer available. I get a 'No HTTP resource was found' error.
How can I extend an API controller that lives in another MVC project?
Is there any way to configure Swagger so that it generates UI & documentation only for a certain API controller within solution, or for a group of API controllers that belong to specific module (project withing solution)?
My solution consist of 50+ projects, several of them contains many API controllers, but I need to enable Swagger only for one of them, located in specific project.
I know about [ApiExplorerSettings(IgnoreApi = true)] attribute, but this way I would need to set this attribute to all API controllers which I don't need, and I would like just to mark the specific API controller which I want to use swagger on.
Is there any way to do that?
You can use conventions for this when registering your controllers.
If you create a new IActionModelConvention, something like this:
public class WhitelistControllersConvention : IActionModelConvention
{
public void Apply(ActionModel action)
{
if (action.Controller.ControllerName == "Item")
{
action.ApiExplorer.IsVisible = true;
}
else
{
action.ApiExplorer.IsVisible = false;
}
}
}
Then use it when configuring swagger in Startup:
services.AddControllers(c =>
{
c.Conventions.Add(new WhitelistControllersConvention());
});
Then you can control which controllers get included. In my example I'm just doing it off the name (only including ItemController), but you can change that to identify the controllers that you want however you want to do it.
I'm trying to create a webapi solution consisting of the main project with other projects as additional endpoints. If the additional projects could not be dependency of the main, that would be great too.
Structure would be something like:
MainWebApiProject accessed as example.com/api/Values
SubProject1 accessed as example.com/sub1/Values
SubProject2 accessed as example.com/sub2/Values
I've created a solution with the 3 projects. I tried setting up the routing in the startup.cs of the MainWebApiProject using Areas and without.
example with the Areas
app.UseMvc(routes =>
{
routes.MapAreaRoute("subProject1_route", "subProject1", "sub1/{controller}/{action}/{id?}");
routes.MapAreaRoute("subProject2_route", "subProject2", "sub2/{controller}/{action}/{id?}");
routes.MapRoute("default_route", "{controller}/{action}/{id?}");
});
then the controller inside SubProject1
[Area("subProject1")]
[Route("sub1/[controller]")]
[ApiController]
public class ValuesController : ControllerBase
{
// GET api/values
[HttpGet]
public ActionResult<IEnumerable<string>> Get()
{
return new string[] { "sub 1 value1", "sub 1 value2" };
}
}
Just not quite sure what I'm missing or doing wrong, or if this can really be done.
I don't see how it is possible if the sub-projects aren't configured as dependency for the main project.
Areas in the new ASP.NET Core, is a feature to logically separate your namespace and views (where views are defined in the area). You would still need to have controllers in the main project to listen for that route.
I wonder, how do you run the sub projects? separately and totally independent of the main one? In that case you will definitely need a different protocol/port for them to be executed and routes will simply not work for them (within the main project).
I've read the question Ioc/DI - Why do I have to reference all layers/assemblies in application's entry point?
So, in a Asp.Net MVC5 solution, the composition root is in the MVC5 project (and having a DependencyInjection assembly in charge of all the registrations does not make sense).
Within this picture, it is not clear to me what is the better approach among the following.
Approach 1
The concrete implementations are public class ... and all registrations clauses are centralized within the composition root (e.g. in one or more files under a CompositionRoot folder). MVC5 project must reference all the assemblies providing at least one concrete implementation to be bound. No library references the DI library. MVC project can contain interfaces to be bound with no drawbacks.
Approach 2
The concrete implementations are internal class .... Each library exposes a DI 'local' configuration handler. For example
public class DependencyInjectionConfig {
public static void Configure(Container container) {
//here registration of assembly-provided implementations
//...
}
}
which is up to register its own implementations. The composition root triggers registrations by calling all the Configure() methods, just one for each project. MVC5 project must then reference all the assemblies providing at least one concrete implementation to be bound. Libraries must reference the DI library. In this case, the MVC5 project cannot contain interfaces (otherwise there would be a circular reference): a ServiceLayer assembly would be needed to hold public interfaces to be bound.
Approach 3
Same as Approach 2, but local configuration modules are discovered dynamically through assembly reflection (by convention?). So MVC5 project has not to reference libraries. MVC project can contain interfaces and can be referenced by libraries. Libraries must reference the DI library.
What is the best practice here? Is there some other better possibility?
EDIT 1 (2016-12-22)
Thanks to received answers, I published this github project describing the best solution I found so far.
EDIT 2 (2018-09-09)
This answer provides an interesting option.
EDIT 3 (2020-12-29)
Finally, I came up with a complete solution, packaged in the form of a WebApi application template. I published this solution on GitHub HERE. This approach, not only gives a clear understanding about where DI rules have to be put, but also suggests to setup the application according to SOLID principles and CQRS pattern. The commit history of this project has been structured to have educational purposes.
EDIT 4 (2023-01-31)
The repository linked above publishes an article describing the solution as well.
I typically like to encapsulate these types of things into each project. So for example I might have the following. (This is an extremely simplified example, and I'll use the AutoFac in this example, but I'd imagine all DI frameworks have something like the following).
Common area for just POCOs and Interfaces.
// MyProject.Data.csproj
namespace MyProject.Data
{
public Interface IPersonRepository
{
Person Get();
}
public class Person
{
}
}
Implementation of Repositories and Data Access
// MyProject.Data.EF.csproj
// This project uses EF to implement that data
namespace MyProject.Data.EF
{
// internal, because I don't want anyone to actually create this class
internal class PersonRepository : IPersonRepository
{
Person Get()
{ // implementation }
}
public class Registration : Autofac.Module
{
protected override void Load(ContainerBuilder builder)
{
builder.Register<PersonRepository>()
.As<IPersonRepository>()
.IntancePerLifetimeScope();
}
}
}
Consumer
// MyPrject.Web.UI.csproj
// This project requires an IPersonRepository
namespace MyProject.Web.UI
{
// Asp.Net MVC Example
internal class IoCConfig
{
public static void Start()
{
var builder = new ContainerBuilder();
var assemblies = BuildManager.GetReferencedAssemblies()
.Cast<Assembly>();
builder.RegisterAssemblyModules(assemblies);
}
}
}
So the Dependencies look like:
MyProject.Data.csproj
- None
MyProject.Data.EF.csproj
- MyProject.Data
MyProject.Web.UI.csproj
- MyProject.Data
- MyProject.Data.EF
In this setup, the Web.UI cannot know anything about what is registered nor for what reason. It only knows that the EF project has implementations but can't access them.
I can drop EF for say Dapper extremely easily as each project encapsulates it's own implementations and registration.
If I was adding unit tests and had an InMemoryPersonRepository, how would I swap out the PersonRepository for my InMemoryPersonRepository?
Assuming we ignore any business logic layer and have an MVC Controller directly access our Data Accessor, my code might look like:
public class MyController
{
private readonly IPersonRepository _repo;
public MyController(IPersonRepository repo)
{
_repo = repo;
}
public IActionResult Index()
{
var person = _repo.Get();
var model = Map<PersonVM>(person);
return View(model);
}
}
Then a test using nSubstitute Might look like:
public class MyControllerTests
{
public void Index_Executed_ReturnsObjectWithSameId
{
// Assign
var repo = Substitute.For<IPersonRepository>();
var expectedId = 1;
repo.Get().Returns(new Person { Id = expected });
var controller = new MyController(repo);
// Act
var result = controller.Index() as ActionResult<PersonVM>;
// Assert
Assert.That(expectedId, Is.EqualTo(result.Value.Id));
}
You've identified a real problem. (One could say it's a good problem to have.) If entry application Areferences B, B references C, and B and/or C require some DI registration, that makes A (your entry application) responsible for knowing enough about the details of B and C to register all the dependencies.
The solution is to have a separate assembly that handles composing all of the registrations for B and C. A references that, and it provides all of the container configuration that A needs to use B and C.
The benefits are
A doesn't know more about B and C than it should
Neither A, B, nor C have to be tied to one particular DI framework like Unity or Windsor.
Here's an example. This is an event bus class that works best with a DI container. But in order to use it you shouldn't have to know all about the dependencies it needs to register. So for Windsor I created a DomainEventFacility. You just call
_container.AddFacility<DomainEventFacility>();
and all of the dependencies are registered. The only thing you register are your event handlers.
Then if I want to use the same event bus library with a different DI container like Unity I can just create some similar assembly to handle the same configuration for Unity.
I'm learning MEF and I wanted to create a simple example (application) to see how it works in action. Thus I thought of a simple translator. I created a solution with four projects (DLL files):
Contracts
Web
BingTranslator
GoogleTranslator
Contracts contains the ITranslate interface. As the name applies, it would only contain contracts (interfaces), thus exporters and importers can use it.
public interface ITranslator
{
string Translate(string text);
}
BingTranslator and GoogleTranslator are both exporters of this contract. They both implement this contract and provide (export) different translation services (one from Bing, another from Google).
[Export(typeof(ITranslator))]
public class GoogleTranslator: ITranslator
{
public string Translate(string text)
{
// Here, I would connect to Google translate and do the work.
return "Translated by Google Translator";
}
}
and the BingTranslator is:
[Export(typeof(ITranslator))]
public class BingTranslator : ITranslator
{
public string Translate(string text)
{
return "Translated by Bing";
}
}
Now, in my Web project, I simply want to get the text from the user, translate it with one of those translators (Bing and Google), and return the result back to the user. Thus in my Web application, I'm dependent upon a translator. Therefore, I've created a controller this way:
public class GeneralController : Controller
{
[Import]
public ITranslator Translator { get; set; }
public JsonResult Translate(string text)
{
return Json(new
{
source = text,
translation = Translator.Translate(text)
});
}
}
and the last piece of the puzzle should be to glue these components (parts) together (to compose the overall song from smaller pieces). So, in Application_Start of the Web project, I have:
var parts = new AggregateCatalog
(
new DirectoryCatalog(Server.MapPath("/parts")),
new DirectoryCatalog(Server.MapPath("/bin"))
);
var composer = new CompositionContainer(parts);
composer.ComposeParts();
in which /parts is the folder where I drop GoogleTranslator.dll and BingTranslator.dll files (exporters are located in these files), and in the /bin folder
I simply have my Web.dll file which contains importer. However, my problem is that, MEF doesn't populate Translator property of the GeneralController with the required translator. I read almost every question related to MEF on this site, but I couldn't figure out what's wrong with my example. Can anyone please tell me what I've missed here?
OK what you need to do is (without prescribing for performance, this is just to see it working)
public class GeneralController : Controller
{
[Import]
public ITranslator Translator { get; set; }
public JsonResult Translate(string text)
{
var container = new CompositionContainer(
new DirectoryCatalog(Path.Combine(HttpRuntime.BinDirectory, "Plugins")));
CompositionBatch compositionBatch = new CompositionBatch();
compositionBatch.AddPart(this);
Container.Compose(compositionBatch);
return Json(new
{
source = text,
translation = Translator.Translate(text)
});
}
}
I am no expert in MEF, and to be frank for what I use it for, it does not do much for me since I only use it to load DLLs and then I have an entry point to dependency inject and from then on I use DI containers and not MEF.
MEF is imperative - as far as I have seen. In your case, you need to pro-actively compose what you need to be MEFed, i.e. your controller. So your controller factory need to compose your controller instance.
Since I rarely use MEFed components in my MVC app, I have a filter for those actions requiring MEF (instead of MEFing all my controllers in my controller facrory):
public class InitialisePluginsAttribute : ActionFilterAttribute
{
public override void OnActionExecuting(ActionExecutingContext filterContext)
{
CompositionBatch compositionBatch = new CompositionBatch();
compositionBatch.AddPart(filterContext.Controller);
UniversalCompositionContainer.Current.Container.Compose(
compositionBatch);
base.OnActionExecuting(filterContext);
}
}
Here UniversalCompositionContainer.Current.Container is a singleton container initialised with my directory catalogs.
My personal view on MEF
MEF, while not a DI framework, it does a lot of that. As such, there is a big overlap with DI and if you already use DI framework, they are bound to collide.
MEF is powerful in loading DLLs in runtime especially when you have WPF app where you might be loading/unloading plugins and expect everything else to work as it was, adding/removing features.
For a web app, this does not make a lot of sense, since you are really not supposed to drop a DLL in a working web application. Hence, its uses are very limited.
I am going to write a post on plugins in ASP.NET MVC and will update this post with a link.
MEF will only populate imports on the objects which it constructs itself. In the case of ASP.NET MVC, it is ASP.NET which creates the controller objects. It will not recognize the [Import] attribute, so that's why you see that the dependency is missing.
To make MEF construct the controllers, you have to do the following:
Mark the controller class itself with [Export].
Implement a IDependencyResolver implementation which wraps the MEF container. You can implement GetService by asking the MEF container for a matching export. You can generate a MEF contract string from the requested type with AttributedModelServices.GetContractName.
Register that resolver by calling DependencyResolver.SetResolver in Application_Start.
You probably also need to mark most of your exported parts with [PartCreationPolicy(CreationPolicy.NonShared)] to prevent the same instance from being reused in several requests concurrently. Any state kept in your MEF parts would be subject to race conditions otherwise.
edit: this blog post has a good example of the whole procedure.
edit2: there may be another problem. The MEF container will hold references to any IDisposable object it creates, so that it can dispose those objects when the container itself is disposed. However, this is not appropriate for objects with a "per request" lifetime! You will effectively have a memory leak for any services which implement IDisposable.
It is probably easier to just use an alternative like AutoFac, which has a NuGet package for ASP.NET MVC integration and which has support for per-request lifetimes.
As #Aliostad mentioned, you do need to have the composition initialise code running during/after controller creation for it to work - simply having it in the global.asax file will not work.
However, you will also need to use [ImportMany] instead of just [Import], since in your example you could be working with any number of ITranslator implementations from the binaries that you discover. The point being that if you have many ITranslator, but are importing them into a single instance, you will likely get an exception from MEF since it won't know which implementation you actually want.
So instead you use:
[ImportMany]
public IEnumerable<ITranslator> Translator { get; set; }
Quick example:
http://dotnetbyexample.blogspot.co.uk/2010/04/very-basic-mef-sample-using-importmany.html