自定义错误处理程序抛出错误:无法读取未定义的属性"get"(Injector)

Question

我正在角度4中构建一个自定义错误处理程序,以处理错误拦截器的不同类型的应用程序错误

创建一个基类(app-error.ts)和其他类(例如处理403错误创建类access-denied.ts),这些类扩展了这个基类.

在基类中注入了一个服务toastrService,我想显示来自子类的自定义消息,但是它会给出错误

无法读取未定义的属性'get'

这个问题与OOPS概念有关.我不明白如何获取覆盖父方法或使用我的自定义参数调用.

TS v 2.3.3 angular v 4.3.4

app.module.ts

providers: [
{ provide: ErrorHandler, useClass: AppErrorHandler }
]

注意:AppErrorHandler类与AppError完全不同,AppError扩展了处理系统错误的角度ErorHandler接口.

错误拦截

import { Router } from '@angular/router';
import { Injectable, Injector } from '@angular/core';
import { HttpInterceptor, HttpResponse, HttpRequest, HttpHandler, HttpEvent, HttpErrorResponse
} from '@angular/common/http';
import { Observable } from 'rxjs/Observable';
import 'rxjs/add/operator/do';

import {
    AuthFail,
    BadInput,
    NotFoundError,
    ServerError,
    AppError,
    AccessDenied,
} from '../shared/errors';
import { AuthenticationService } from './../authentication/authentication.service';


@Injectable()
export class ErrorInterceptor implements HttpInterceptor {

    private auth: AuthenticationService;
    constructor(private router: Router, private injector: Injector) { }
    intercept(req: HttpRequest<any>, next: HttpHandler): Observable<HttpEvent<any>> {
        const auth = this.injector.get(AuthenticationService);
        return next.handle(req).catch((err: HttpErrorResponse) => {
            if (err instanceof HttpErrorResponse) {
                if (err.status === 401) {
                    return Observable.throw(new AuthFail(err.error));
                }
                if (err.status === 400) {
                    return Observable.throw(new BadInput(err.error));
                }
                if (err.status === 404) {
                    return Observable.throw(new NotFoundError());
                }
                if (err.status === 403) {
                    return Observable.throw(new AccessDenied());
                }
                return Observable.throw(new AppError(err));
            }
        });
    }
}

访问denied.ts

import { AppError } from './app-error';
export class AccessDenied extends AppError {
    constructor(public originalError?: any) {
        super();
        console.log('inside acces denied constructor');
        // super.handleError("superrrrr"); // this also doesn't work
    }

    public handleError(): void {
        console.log('handleError: ', );
        super.handleError("Access denined error occured");
    }
}

APP-error.ts

import { Inject, Injector } from "@angular/core";

import { ToastrService } from "ngx-toastr";

export class AppError {
    toastrService: ToastrService;
    constructor(public originalError?: any, private injector?: Injector) {
        this.toastrService = this.injector.get(ToastrService);
    }

    // NOTE: using getter seems impossible to access in child so add the same in constructor
    // get toastrService(): ToastrService {
    //  return this.injector.get(ToastrService);
    // }

    public handleError(msg: string): void {
        this.toastrService.error(`Error Message: ${msg}`,
            "Error", {
                closeButton: true,
                timeOut: 5000,
                onActivateTick: true
            }
        );
    }

}

给出错误

---

core.es5.js:1020 ERROR TypeError: Cannot read property 'get' of undefined 
    at AccessDenied.AppError (app-error.ts:8) 
    at new AccessDenied (access-denied.ts:6)  
    at CatchSubscriber.eval [as selector] (error.interceptor.ts:61) 
    at CatchSubscriber.error (catchError.js:105)
    at XMLHttpRequest.onLoad (http.es5.js:1739)
    at ZoneDelegate.invokeTask (zone.js:421)
    at Object.onInvokeTask (core.es5.js:3881)
    at ZoneDelegate.invokeTask (zone.js:420)
    at Zone.runTask (zone.js:188)
    at ZoneTask.invokeTask [as invoke] (zone.js:496)

Answer 1

AccessDenied错误地延伸AppError。super()导致injector未定义，并且injector在构造函数中不应该是可选的AppError，因为它是必需的。

它可以通过强制参数来修复：

constructor(private injector: Injector, public originalError?: any) {
    this.toastrService = this.injector.get(ToastrService);
}

中的构造函数可以省略AccessDenied。并且应该像这样实例化new AccessDenied(injector)。

这里真正的问题是AppError做了不应该做的工作。考虑到它只包含稍后可以用 确定的错误err instanceof AppError，它不应该产生当前在 中完成的副作用handleError。

中的逻辑handleError可以移动到ToastrService接受 的实例的方法或单独的错误服务中AppError。如果需要为错误类型（例如 ）提供默认消息Access denied error occurred，AppError可以拥有包含该消息的公共属性。