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Dependency Injection for A Proxy Class Object

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thexeb

10 Mar, 2014 10:13 PM

Hi , sorry if the question is ridiculous or redundant , but i could not find anything in discussion area.As i do AS3 programming as a hobby so i try to explain my problem.
I am working on an App , which will have two versions , one "Offline" and the other one "Online" , with respective "Service" to persistence media. I will be configuring App to use different implementation for IService.

...config.as
context.injector.map(IService,"SQLITE_SERVICE").toSingleton(SqlLiteDBService);
context.injector.map(UserVOProxy);

In my previous App , i used Mediator or Command to use IService and fillup the VOs'.
Now I am mediating VO's with a Proxy class, and By Proxy pattern , it will be loading the VO .
So i am trying

...UserVOProxy.as
[Inject]
public var service:IService;
[Inject]
public var injector:IInjector;

but both are not working , the objects are null when i debug.
Also i need multiple instances of UserVOProxy , so i don't want a Singleton implementation . As this proxy may contain another proxies of some VOs' , i think it would be better to let the proxies handle the loading of data when required. Also i used a kind of 'hack' by providing Injector object from Medaitor when creating Proxy. But there may be many Views-Mediator and there will be different Number of Proxy objects based on user selection.A single View will be displaying different UserVO under selection.
Can anyone help ,What am i missing? or this approach is all wrong?

1. Support Staff 1 Posted by Ondina D.F. on 11 Mar, 2014 08:45 AM

   

   Hello,

   If you map your service like this

   context.injector.map(IService, "SQLITE_SERVICE").toSingleton(SqlLiteDBService);
   

   You must use the name in your Inject metatag for the injection to occur:

   [Inject (name="SQLITE_SERVICE")]
   public var service:IService;
   

   This is incomplete, it only maps a request description :

   context.injector.map(UserVOProxy);
   

   Also i need multiple instances of UserVOProxy , so i don't want a Singleton implementation

   See the difference between asSingleton()and toType

   injector.map(SomeModel).asSingleton();
   asSingleton and toSingleton - Makes the mapping return a lazily constructed singleton instance of the mapped type for each consecutive request.

   injector.map(ISomeModel).toType(SomeModel);
   toType - Makes the mapping return a newly created instance of the given type for each consecutive request.

   .asSingleton (), .toType () return the InjectionMapping the method is invoked on

   Let me know if it helped.

   Ondina

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2. 2 Posted by thexeb on 13 Mar, 2014 12:19 PM

   

   thanks alot ondina , i thought may be i could use without implementing some interface .

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3. Support Staff 3 Posted by Ondina D.F. on 18 Mar, 2014 08:36 AM

   

   My pleasure:)

   i thought may be i could use without implementing some interface .

   What do you mean?

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4. 4 Posted by thexeb on 19 Mar, 2014 12:04 PM

   

   i meant to say that proxy should be implementing IProxy , so that it is Mapped to concrete class instance, as u said

   context.injector.map(UserVOProxy);
   

   is incomplete.

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5. Support Staff 5 Posted by Ondina D.F. on 19 Mar, 2014 12:35 PM

   

   Yes. Depending on what you need, you can use
   .asSingleton(), .toSingleton(), .toValue(), or .toType()

   If SomeService is implementing an interface, IService, then you map it like this:

   injector.map(IService).toSingleton(SomeService);

   or like so

   injector.map(IService).toType(SomeService);

   and if it's not implementing an interface:

   injector.map(SomeService).asSingleton();

   or

   injector.map(SomeService).toType(SomeService);

   Letting services and models implement an interface is a good practice, though.

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6. Support Staff 6 Posted by Ondina D.F. on 19 Mar, 2014 12:49 PM

   

   I guess this is resolved. I'm going to close this discussion, but you can re-open it, if need be.

   Cheers,
   Ondina

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7. Ondina D.F. closed this discussion on 19 Mar, 2014 12:49 PM.