注入类数组

问题描述

我有一个MetaManager类:

I have a MetaManager class:

@Injectable()
export class MetaManager{

    constructor(private handlers:Handler[]){
        console.log(handlers);
    }
}

此类需要一个 Handler [] 才能注册为处理程序.然后，当我获得一些元数据时，我在处理程序数组中循环查看哪个可以处理我的元条目.

this class needs a Handler[] to register as handlers. Than, when I get some metadata, I loop in my handlers array to see which one can handler my meta entry.

话虽这么说，问题是我无法在main.ts中提供一个类数组作为config，这是我尝试过的(以及不起作用的地方):

Having said that, problem is that I can't provide an array of class as config in main.ts, here is what I have tried (and what did not work):

在MetaManager中使用字符串条目(带有 @Provide('HANDLERS')注释)

Using String entry (with a @Provide('HANDLERS') annotation in MetaManager:

`bootstrap(AppComponent, [MetaManager,provide('HANDLERS', {useValue: [DebugHandler]}) ]);`

使用接口提供处理程序:

Using an interface to provide handlers:

export const HANDLERS: HandlerConfig = {handlers: [<Handler>DebugHandler]};

bootstrap(AppComponent, [MetaManager, provide(HandlerConfig, {useValue: HANDLERS}) ]);

使用 Handler [] 类提供程序:

bootstrap(AppComponent, [MetaManager, provide(Handler[], [DebugHandler])]);

我想提供一个类数组，因为 MetaManager 将来将需要有多个处理程序，通知，错误等...

I want to provide a class array because MetaManager will need to have more than one Handler in the future, notification, error, etc...

使用多提供程序给了我没有Array的提供程序！(ApiService-> MetaManager->数组)错误:

Using multi provider gives me a No provider for Array! (ApiService -> MetaManager -> Array) Error:

meta-manager.ts:

meta-manager.ts:

@Injectable()
export class MetaManager{

    constructor(private handlers:Handler[]){
        console.log(handlers);
    }
}

main.ts:

bootstrap(AppComponent,
    [   MetaManager,
        provide(Handler, {useClass: DebugHandler, multi: true}),
        provide(Handler, {useClass: NotificationHandler, multi: true})]);

推荐答案

在为 Handler 类注册提供程序时，可以使用 multi 属性:

You could use the multi attribute when registering your providers for the Handler class:

bootstrap(AppComponent, [
  MetaManager,
  provide(Handler, { useClass: DebugHandler, multi: true }),
  provide(Handler, { useClass: OtherHandler, multi: true })
]);

这样，您就可以通过这种方式进行注入:

This way, you will be able to inject this way:

@Injectable()
export class MetaManager{
  constructor(@Inject(Handler) private handlers:Handler[]){
    console.log(handlers);
  }
}

以下是相应的插件: https://plnkr.co/edit/UBIvWfOvAmo4XO2ohbID?p=预览.本文可能会让您感兴趣:

Here is the corresponding plunkr: https://plnkr.co/edit/UBIvWfOvAmo4XO2ohbID?p=preview.This article could interest you:

• http://blog.Thoughtram.io/angular2/2015/11/23/multi-providers-in-angular-2.html

这篇关于注入类数组的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！