Attached my screenshot which is entry level rest class, where used #Component. Why used #Component ?
I gone through below blog
http://www.benchresources.net/jersey-2-x-web-service-integrating-with-spring-framework-using-annotation/
#Component, #Resource, #Service used because you are still using spring framework application for dependency injection, specifically to link to found classes by component scan, and you want it to be able to autowire spring components as you service or dao classes
Related
I'm using Mapster for mapping and Simple Injector in my .net framework 4.8 MVC and WebApi controllers.
I'd like to inject Mapster as a dependency in my services but I can't figure it out how to make it work with Simple Injector. The Mapster documentation is really vague in my opinion:
Mapster - Dependency Injection
Mapster - References
Can someone provide and example of how to use Mapster with Simple Injector? Doesn't matter if the controller is mvc or a web api.
The code I need is the configuration in Application_Start in Global.asax.cs and in the service concrete. Thanks!
I'm unfamiliar with Mapster, but after looking at the documentation link you provided, I'm assuming that integrating with Simple Injector can be done as follows:
var config = new TypeAdapterConfig();
container.RegisterInstance(config);
services.RegisterSingleton<IMapper, SimpleInjectorMapper>();
Where SimpleInjectorMapper is:
public sealed class SimpleInjectorMapper : ServiceMapper
{
public SimpleInjectorMapper(
Container container, TypeAdapterConfig config)
: base(container, config)
{
}
}
The 'trick' here is that the Simple Injector Container class implements System.IServiceProvider, which is the base interface used by most of the DI facilities in .NET and .NET Core and is the base interface that the MS.DI abstraction relies on. Mapsters ServiceMapper expects an IServiceProvider in its constructor, which is now provided using the Container.
There are a few downsides to this approach. Main downside is that in case a dependency is missing, you'll get a more generic "no service registered" exception in line with what MS.DI would throw, instead of a very information rich exception that Simple Injector would throw in case the resolve would fail when you call Container.GetInstance.
This, however, is a as far as I can go in providing an answer. If you wish to integrate more deeply with Simple Injector, you likely need a more complex SimpleInjectorMapper implementation, but others (e.g. the designers behind Mapster) need to help you with that. At least, hopefully, this answer will get you started.
I'm using Xamarin.Forms with Prism. I'm using the Dependency Injection provided by prism. (also to inject instances of my own classes, not only platform specific)
My question is how can I pass parameters to the constructor in Dependency Injection?
Thanks
You normally don't pass parameters via a ctor. You only inject your class dependencies such as services. To inject your services just register them with the container in the RegisterTypes method in the App.cs
Assuming you are using Unity:
Container.RegisterType<IMyService, MyService>(optionally make it a singleton)
I need to upgrade a medium sized web application from Spring 2.5 to Spring 4.x.
I replaced Spring 2.5 jars with 4.3.2 jars and I found around 100 errors like SimpleFormController name not resolved, queryforInt() not recognized etc. Should I use #Controller for controllers and use auto-wire the dependencies ?. That means I should convert all classes to annotation based using #component, #Resource, #Controller etc ? What is the best approach...Please suggest
You need to move from using SimpleFormController, it has been deprecated from spring 3.x and removed in 4.x. Start writing your controllers with #Controller annotation.
Should you use #Component, #Service, and autowire? It's probably best you do that, but not necessarily. You can still use your factory classes to create objects if you want. But using spring #Autowired dependency would make your life easier.
Each tutorial or example that I've found for using DI in ASP.NET 5 only shows how it works with Controllers and Razor Views. I need to use DI for other classes but don't know the proper way to resolve types and provide an instance. Right now I have an instance of a HackyDependencyResolver that everything must reference in order to get the proper instances. I want to either access ASP.NET's service resolver or follow some other best-practice for resolving dependencies.
For example if I have
public class SomeClass
{
public SomeClass(IUseMe useMe)
{
}
}
which is not an ASP.NET MVC Controller. I need a pattern for resolving a correct instance for IUseMe when SomeClass is created. Certainly I can make my own global factory, but is that the best way?
DI has nothing to do with asp.net, controllers or views. In the end all are classes. Considering that an action is an entrypoint in your app, any service you need there should be injected, The service itself has some dependencies and those will be injected automatically by the DI Container when it instantiates the controller.
All you have to do is to define your services (not every object needs injected deps) then register those services into the Di Container.
How do I resolve IUseMe so that I'm not dependent on a particular implementation?
You don't. The Di Container does that based on configuration, when the controller is instantiated. Everything has a flow, you don't just pick classes out of thin air and say "I want this created by the Di container". OK you could, but it would be the wrong approach.
The whole point of using a DI Container is not to care about instantiating services. The framework takes care of integrating with the container, your only job is to define the classes properly and to configure the container .
I read the article yesterday: https://igor.io/2012/11/09/scaling-silex.html
And another one http://davedevelopment.co.uk/2012/10/03/Silex-Controllers-As-Services.html
So a conceptual question rised in my head:
Currently I do have a lot of controllers in separate classes. I overwrite controller_resolver to create a controller class instance and inject $app into contoller's constructor.
I define routes like this $app->get('/hello', 'HelloController::indexAction') <- my controller resolver will create new HelloController($app); - so far so good.
But to be honest it became a ServiceLocator pattern, not a DependencyInjection, because I do inject whe whole $app which looks like ServiceLocator usage.
Now I am in doubt: should I leave it as is (because it works well) or try "controllers as services" to inject only those sevices on which my controller really depends on? May be my SeviceLocator approach will hit me some day? (people say that DI is better for tests).
I have also looked into Symfony Framework Bundle: class Controller extends abstract class ContainerAware which also have the whole $container injected! ServiceLocator approach in full stack framework?
Any recomendation? Pros/cons?
The symfony2 full-stack framework
The framework uses the Dependency Injection pattern and not the Service Locator pattern.
All controllers aren't services by default. The ContainerAware class includes methods to get access to the service container, so you can call Services inside the Controller.
If you are going to use a Controller as a Service you need to remove the Controller extend. All dependencies you want to use inside the controller needs to be injected by the Service Container.
Read more about this in a blogpost by richard miller, one of the core contributors of Symfony2.
The Silex micro-framework
The Silex micro-framework provides the bare bones of a framework, it's up to you how the architecture looks and which patterns you use.
The Silex documentation uses Controllers that aren't Services. It injects the complete Service Container inside very Controller:
$app->post('/post/{id}-{slug}', function($id, $slug) use ($app) {
// ...
});
If you want to use controllers as service, you should only inject the services you want to use inside the controller.
EDIT: The Controller::action syntax refers also to a Controller that isn't a Service. The Controller:action notation is used to refer to Controllers as Services.
There's lot's of personal preference involved here. What you've done already is a good (enough) step to organising your code base. Some people like myself take things a step further and move our controllers to the container, rather than injecting it in to some kind of BaseController. This happens in both Silex and the full stack Symfony framework.
My advice would be to leave everything you have as is, then try defining your next controller as a service, by practising BDD.
For example, the behaviour of a UserController view action:
It should retrieve the user from a database
It should render the user with a template
Not once does it mention retrieving the database or the template renderer from a container. I'm comfortable not injecting the container, so I'll only inject what I'm led to believe I need by BDD.