Ionic2如何在提供程序中获取NavController

Question

我创建了AuthHttpProvider,它是Http包装器,允许发送GET/POST/PUT/DELETE请求并自动为每个请求添加身份验证令牌(jwt).我在所有的ionic2应用程序中使用这个包装器而不是Http.现在,当我检测到来自服务器的任何响应有403 Http错误代码时,我想注销用户(并转到loginPage).

因此,当我尝试在构造函数中注入NavController(在403检测后将其用于loginPage)

constructor (public navCtrl: NavController)

我明白了:

Uncaught (in promise): Error: No provider for NavController

如何访问Provider内的navCtrl？

Answer 1

这是解决方案(从这里):

import { Injectable, Injector } from '@angular/core';
import { Http, Headers } from '@angular/http';
import { Observable } from "rxjs";
import 'rxjs/add/operator/map';
import { App } from "ionic-angular";
import { NavController } from "ionic-angular/index";
import { LoginPage } from "../../pages/login/login";
...

@Injectable()
export class AuthHttpProvider {

  private navCtrl: NavController;
  ...

  constructor(public http: Http, ..., private app:App ) {
    this.navCtrl = app.getActiveNav();
  }

  get(url) {  // http GET
    return this.http.get(url, this.getHeaders() )
                    .catch(this.globalErr(this));
  }

  // ... http POST/PUT/DELETE

  private getHeaders() { ... } //(cors, csrf-token ...)

  private globalErr(self) {
    return (err) => {
      if ( err.status == 403 ) { self.logout(); }
      return Observable.throw(err);
    };
  }

  public logout() {
    // ...
    this.navCtrl.setRoot(LoginPage);
    this.navCtrl.popToRoot;
  }
}

但更好的方法是,如果Provider能够引发一些事件/异常,UI将能够拦截它并将视图更改为loginPage