如何在angular 6+中创建和导入自定义错误消息文件

{
  "required": "该字段为必填字段。"
}

ng generate service error-messages

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';

@Injectable({
  providedIn: 'root'
})
export class ErrorMessagesService {
  private errorMessages: any;

  constructor(private http: HttpClient) { }

  loadErrorMessages(): Promise<any> {
    return this.http.get('assets/i18n/error-messages.json')
      .toPromise()
      .then((data: any) => {
        this.errorMessages = data;
      });
  }

  getErrorMessage(key: string): string {
    return this.errorMessages[key] || '';
  }
}

import { Component, OnInit } from '@angular/core';
import { ErrorMessagesService } from '../error-messages.service';

@Component({
  selector: 'app-your-component',
  templateUrl: './your-component.component.html',
  styleUrls: ['./your-component.component.css']
})
export class YourComponent implements OnInit {

  constructor(private errorMessagesService: ErrorMessagesService) { }

  ngOnInit(): void {
    this.errorMessagesService.loadErrorMessages()
      .then(() => {
        // 错误消息加载完成
      });
  }

  getCustomErrorMessage(): string {
    return this.errorMessagesService.getErrorMessage('required');
  }
}

<p>{{ getCustomErrorMessage() }}</p>