如果同时在HTML中包含组件以及通过DI注入组件，为什么会出现StaticInjector错误 [英] Why do I get StaticInjector error if I include a component both in HTML as well as inject it via DI

问题描述

我有一个使用LoginFormComponent的组件ValidateSessionComponent.我通过在ValidateSessionComponent的HTML中包含LoginFormComponent在ValidateSessionComponent中使用LoginFormComponent.

I have a component ValidateSessionComponent which uses LoginFormComponent. I use LoginFormComponent in ValidateSessionComponent by including it in the HTML of the ValidateSessionComponent.

到目前为止，这个方法工作正常.然后，我决定通过DI在ValidateSessionComponent

This works fine so far. Then I decided to also include reference of LoginFormComponent via DI in ValidateSessionComponent

constructor(private loginForm2:LoginFormComponent,private helper:HelperService,private dialogService:DialogBoxService,private activatedRoute:ActivatedRoute, private router:Router, private userManagementService:UserManagementService) { }

这开始导致错误StaticInjectorError(DynamicTestModule)[ValidateSessionComponent -> LoginFormComponent]: StaticInjectorError(Platform: core)[ValidateSessionComponent -> LoginFormComponent]: NullInjectorError: No provider for LoginFormComponent!

This started causing the error StaticInjectorError(DynamicTestModule)[ValidateSessionComponent -> LoginFormComponent]: StaticInjectorError(Platform: core)[ValidateSessionComponent -> LoginFormComponent]: NullInjectorError: No provider for LoginFormComponent!

为什么我开始出现错误?

Why do i start getting the error?

推荐答案

因为DI仅适用于提供者.

Because DI works only for providers.

组件不是提供程序.

如果希望获得对子元素的引用，请改用ViewChild.

If you wish to get a reference to your child element, use a ViewChild instead.

@ViewChild(LoginFormComponent, { static: true }) loginForm: LoginFormComponent;

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