Angular - 未捕获的错误：无法解析 HomeComponent 的所有参数：（？，？，？，？）

Question

运行 Angular 项目时出现错误

未捕获的错误：无法解析 HomeComponent 的所有参数：(?, ?, ?, ?)。

HomeComponent 调用了四个服务。所有服务均由Injectable 提供。当从构造函数中删除所有服务时运行正常，但添加这些服务会导致问题。

HomeComponent.ts

import { Component, OnInit } from '@angular/core';
import { PashminaModel } from '../../model/pashmina.model';
import { HomeService } from '../../services/home-service/home-service';
import { Category } from "../../enum/Enum";
import { FooterService } from "../../services/footer/footer.service";
import { NavbarService } from "../../services/navbar/navbar.service";
import { DataService } from '../../services/data-service/data.service';

@Component({
    selector: 'app-home',
    templateUrl: './home.component.html',
    styleUrls: ['./home.component.scss']
})
constructor(
        private homeService: HomeService,
        private navService: NavbarService,
        private footerService: FooterService,
        private data: DataService
    ) {
}

------
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这就是我在app.module.ts 中实现提供程序部分的方式

providers: [
        AuthorizationComponent,
        NavbarService,
        FooterService,
        LoginServiceEndpoint,
        LoginService,
        PashminaServiceEndpoint,
        PashminaService,
        ImageServiceEndpoint,
        ImageService,
        DescriptionServiceEndpoint,
        DescriptionService,
        ColorServiceEndpoint,
        ColorService,
        HomeService,
        HomeServiceEndpoint,
        AccountService,
        AccountServiceEndpoint,
        OrderServiceEndpoint,
        OrderService,
        DataService
    ],

之前可以正常工作但是突然出现这个错误。

Answer 1

在pollyfills.ts 中，您应该已经注释了这两行：

import 'core-js/es6/reflect';
import 'core-js/es7/reflect';

取消注释。它应该可以完美运行。

Answer 2

您已在提供程序中添加了 AuthorizationComponent，从提供程序中删除所有组件并将它们添加到 declarations

providers: [
        AuthorizationComponent,  //remove from here and add under declarations
        NavbarService,
        FooterService,
        LoginServiceEndpoint,
        LoginService,
        PashminaServiceEndpoint,
        PashminaService,
        ImageServiceEndpoint,
        ImageService,
        DescriptionServiceEndpoint,
        DescriptionService,
        ColorServiceEndpoint,
        ColorService,
        HomeService,
        HomeServiceEndpoint,
        AccountService,
        AccountServiceEndpoint,
        OrderServiceEndpoint,
        OrderService,
        DataService
 ]