Angular2中的循环依赖问题

Question

I developed a custom error handler which implements Angular2 Error Handler class. My custom error handler uses a logger service to log errors. The code looks like as follows:

export class CustomErrorHandler implements ErrorHandler {
    constructor(private logger: LoggerService) {}

    handleError(error: any): void {
        logger.error('....');
    }
}

However, since the logger service uses Angular2 router, I cannot inject the logger service to the custom error handler! Running the above code throws the following exception! Error: Provider parse errors:↵Cannot instantiate cyclic dependency!

Answer 1

You need to inject manually, to avoid the cyclic dependency problem because this class is created before the providers, your code should be:

import { Injectable, Injector } from '@angular/core';
import { Logger } from '...';

@Injectable()
export class CustomErrorHandler implements ErrorHandler {
    constructor(private injector: Injector) {}

    handleError(error: any): void {
        const logger = this.injector.get(Logger);
        logger.error('....');
    }
}