NullInjectorError:NgZone没有提供者！ (Angular 6库) [英] NullInjectorError: No provider for NgZone! (Angular 6 library)

问题描述

我创建了一个Angular 6库，但是尝试在创建它的项目之外使用它时收到错误消息.这看起来像很多代码，但主要是CLI生成的样板文件.

I created an Angular 6 library, but I get an error when I try to use it outside of the project in which it was created. This looks like a lot of code, but it's mostly boilerplate generated by the CLI.

我使用Angular 6 CLI创建了一个非常基本的库.

I created a very basic library with the Angular 6 CLI.

ng new mylib 
cd mylib
ng generate library example
ng build --prod example

然后我可以将<lib-example></lib-example>添加到src/app/app.component.html，运行ng serve，然后查看示例组件是否按预期工作.

I can then add <lib-example></lib-example> to src/app/app.component.html, run ng serve, and see the example component works as expected.

接下来，我编辑projects/example/src/lib/example.component.ts，将*ng-if="true"添加到<p>标签.

Next I edit projects/example/src/lib/example.component.ts to add an an *ng-if="true" to the <p> tag.

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'lib-example',
  template: `
    <p *ng-if="true"> <!-- this line was changed -->
      example works!
    </p>
  `,
  styles: []
})
export class ExampleComponent implements OnInit {

  constructor() { }

  ngOnInit() {
  }

}

要获取ngIf指令，请导入BrowserModule，因此我的projects/example/src/lib/example.module.ts如下所示:

To get the ngIf directive, I import BrowserModule, so my projects/example/src/lib/example.module.ts looks like this:

import { NgModule } from '@angular/core';
import { ExampleComponent } from './example.component';
import { BrowserModule } from '@angular/platform-browser'; // added

@NgModule({
  imports: [
    BrowserModule // added
  ],
  declarations: [ExampleComponent],
  exports: [ExampleComponent]
})
export class ExampleModule { }

重建:

ng build --prod example

我的组件还没有做任何有用的事情，但是只要我在用于创建它的同一个项目中使用它，它就可以工作.

My component doesn't do anything useful yet, but it works as long as I use it within the same project I used to create it.

让我们尝试在其他应用中使用该库.我首先生成一个新应用程序，该应用程序与包含该库的应用程序位于同一目录中.

Let's try using the library in a different app. I start by generating a new app that lives in the same directory as the app that contains the library.

ng new myapp 

然后我将<lib-example></lib-example>添加到myapp/src/app/app.component.html并将库导入到myapp/src/app/app.module.ts中，使其看起来像这样.

Then I add <lib-example></lib-example> to myapp/src/app/app.component.html and import the library in myapp/src/app/app.module.ts, so that it looks like this.

import { BrowserModule } from "@angular/platform-browser";
import { NgModule } from "@angular/core";

import { AppComponent } from "./app.component";
import { ExampleModule } from "../../../mylib/dist/example"; // added

@NgModule({
  declarations: [AppComponent],
  imports: [
     BrowserModule,
     ExampleModule // added
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule {}

错误消息

浏览到应用程序时，在控制台中出现以下错误.

Error Message

When I browse to the app, I get the following error in the console.

Error: StaticInjectorError(AppModule)[ApplicationRef -> NgZone]: 
  StaticInjectorError(Platform: core)[ApplicationRef -> NgZone]: 
    NullInjectorError: No provider for NgZone!
    at NullInjector.push../node_modules/@angular/core/fesm5/core.js.NullInjector.get (core.js:1060)
    at resolveToken (core.js:1298)
    at tryResolveToken (core.js:1242)
    at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:1139)
    at resolveToken (core.js:1298)
    at tryResolveToken (core.js:1242)
    at StaticInjector.push../node_modules/@angular/core/fesm5/core.js.StaticInjector.get (core.js:1139)
    at resolveNgModuleDep (core.js:8377)
    at _createClass (core.js:8430)
    at _createProviderInstance (core.js:8394)

我在做什么错了?

推荐答案

好吧，我不知道为什么.但是问题出在导入BrowserModule上.不要将其导入到您的库模块中，它应该可以工作.

Well, I don't know why. But the problem is with importing the BrowserModule. Do not import it into your library module and it should work.

import { NgModule } from '@angular/core';
import { ExampleComponent } from './example.component';
//import { BrowserModule } from '@angular/platform-browser'; // added

@NgModule({
  imports: [
   // BrowserModule // removed
  ],
  declarations: [ExampleComponent],
  exports: [ExampleComponent]
})
export class ExampleModule { }

我已经很长时间了，并逐一删除了我的库模块中的导入内容.是BrowserModule.

I have been in this for a very long time and removed the imports in my library module one by one. It was the BrowserModule.

我认为这应该回答您其他的问题.

I think this should answer your other question.

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