无法阅读财产＆all.docs＆＃39;刷新页面后

Question

当刷新页面时，似乎与CouchDB的连接正在重置。

我正在使用Couchdb和Pouchdb创建一个简单的待办事项应用程序，如Blog所示。一切似乎都有效，但是当通过单击浏览器刷新按钮刷新HomePage时，我遇到了问题。使用提供商提取数据。

home.ts 从 provider.ts

加载数据

ngOnInit(){
  this.DbProvider.getTodos().then((data) => {
    this.todos = data;
  });
}

getTodos() {
  if (this.data) {
    return Promise.resolve(this.data);
  }

  return new Promise(resolve => {
    this.db.allDocs({
      include_docs: true
    }).then((result) => {
      this.data = [];
      let doc = result.rows.map((row) => {
        this.data.push(row.doc);
      });
      resolve(this.data);

      this.db.changes({live: true, since: 'now', include_docs: true}).on('change', (change) => {
        this.handleChange(change);
      });
    }).catch((error) => {
      console.log(error);
    }); 
  });
}

provider.ts

import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';
import 'rxjs/add/operator/map';
import PouchDB from 'pouchdb';

@Injectable()
export class DbProvider {
  data: any;
  db: any;
  remote: any;

  constructor() {}
  init(details){
    this.db = new PouchDB('myDB');
    this.remote = details.userDBs.supertest;
    let options = {
      live: true,
      retry: true,
      continuous: true
    };
    this.db.sync(this.remote, options); 
    console.log(this.db);
  }
}

我遇到的错误

    ERROR Error: Uncaught (in promise): TypeError: Cannot read property 'allDocs' of undefined
TypeError: Cannot read property 'allDocs' of undefined
at provider.ts:61
at new t (polyfills.js:3)
at DbProvider.webpackJsonp.201.DbProvider.getTodos (provider.ts:59)
at HomePage.webpackJsonp.317.HomePage.ngOnInit (home.ts:38)
at checkAndUpdateDirectiveInline (core.js:12095)
at checkAndUpdateNodeInline (core.js:13598)
at checkAndUpdateNode (core.js:13541)
at debugCheckAndUpdateNode (core.js:14413)
at debugCheckDirectivesFn (core.js:14354)
at Object.eval [as updateDirectives] (HomePage_Host.ngfactory.js? [sm]:1)
at provider.ts:61
at new t (polyfills.js:3)
at DbProvider.webpackJsonp.201.DbProvider.getTodos (provider.ts:59)
at HomePage.webpackJsonp.317.HomePage.ngOnInit (home.ts:38)
at checkAndUpdateDirectiveInline (core.js:12095)
at checkAndUpdateNodeInline (core.js:13598)
at checkAndUpdateNode (core.js:13541)
at debugCheckAndUpdateNode (core.js:14413)
at debugCheckDirectivesFn (core.js:14354)
at Object.eval [as updateDirectives] (HomePage_Host.ngfactory.js? [sm]:1)
at c (polyfills.js:3)
at c (polyfills.js:3)
at polyfills.js:3
at t.invokeTask (polyfills.js:3)
at Object.onInvokeTask (core.js:4620)
at t.invokeTask (polyfills.js:3)
at r.runTask (polyfills.js:3)
at o (polyfills.js:3)
at <anonymous>