angular - 无法将ChangeDetectorRef添加为提供者

Web请求后，我正在使用ChangeDetectorRef更新 View 。

import { Component, OnInit, ChangeDetectorRef } from '@angular/core';
import { HttpClient } from '@angular/common/http';
import { QRCodeModule } from 'angularx-qrcode';

@Component({
  selector: 'app-print',
  templateUrl: './print.component.html',
  styleUrls: ['./print.component.css'],
})
export class PrintComponent implements OnInit {
  barcodeitems;
  selecteditems = [];

  constructor(public http: HttpClient, private cdr: ChangeDetectorRef){

  }

  ngOnInit(): void {

  }

  getqr() {
    console.log("selecteditems array", this.selecteditems);
    let filterQuery = this.selecteditems.map(i => `ID eq '${i}'`).join(" or ");
    let url = `https://example.com/corporate/dev/_api/web/lists/getbytitle('Document Separator Barcodes')/items?$top=1000&$orderBy=ID&$filter=${filterQuery}`
    this.http.get(url).subscribe(data => {
      this.barcodeitems = data['value'];

      this.cdr.detectChanges();

    });
  }

}

使用ng serve，我得到一个错误:Error: StaticInjectorError(AppModule)[PrintComponent -> ChangeDetectorRef]: StaticInjectorError(Platform: core)[PrintComponent -> ChangeDetectorRef]: NullInjectorError: No provider for ChangeDetectorRef!。

我试图将ChangeDetectorRef添加到app.module.ts中的providers中，如下所示:

import { NgModule, ChangeDetectorRef } from '@angular/core';
.....

import { AppComponent } from './app.component';
import { PrintComponent } from './print/

print.component';

@NgModule({
  declarations: [
    AppComponent,
    PrintComponent,
  ],
  imports: [
    BrowserModule,
    HttpClientModule,
    QRCodeModule,
    FormsModule,
  ],
  providers: [PrintComponent, ChangeDetectorRef],
  bootstrap: [AppComponent]
})
export class AppModule { }

这给我一个错误:

Argument of type '{ declarations: (typeof AppComponent | typeof PrintComponent)[]; imports: (typeof BrowserModule |...' is not assignable to parameter of type 'NgModule'. Types of property 'providers' are incompatible. Type '(typeof PrintComponent | typeof ChangeDetectorRef)[]' is not assignable to type 'Provider[]'. Type 'typeof PrintComponent | typeof ChangeDetectorRef' is not assignable to type 'Provider'. Type 'typeof ChangeDetectorRef' is not assignable to type 'Provider'. Type 'typeof ChangeDetectorRef' is not assignable to type 'FactoryProvider'. Property 'provide' is missing in type 'typeof ChangeDetectorRef'.

如何添加ChangeDetectorRef作为提供者？

最佳答案

为什么要提供PrintComponent？您无法提供组件...。从模块中完全删除提供程序，它应该可以工作。

关于angular - 无法将ChangeDetectorRef添加为提供者，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/48910362/