javascript - Promise then 函数中的 Angular 4 持久存储使用情况

Question

尝试在 Promise then 函数中使用 Angular 持久性，但总是显示未定义

import { Component, OnInit, Injectable } from '@angular/core';

import {Router} from "@angular/router";
import {PersistenceService, StorageType} from "angular-persistence";

export class ProcessingComponent implements OnInit {

  myfunc: any;

  constructor(private PersistenceService: PersistenceService ){
  }


  ngOnInit() {

    this.myfunc = new myfunction();



    this.shaObj.generateIdentity().then(function (result, PersistenceService) {
      console.log(PersistenceService.set('identityKey')); // getting undefined
    }.bind(this.PersistenceService));

  }

所以绑定(bind)服务似乎不起作用，如何将外部作用域“this”传递到“.then”函数中。

Answer 1

您应该使用this.injectableName而不是直接使用ClassName

console.log(PersistenceService.set('identityKey'));

应该是

console.log(this.PersistenceService.set('identityKey'));

Note: As per guideline and to avoid confusion use cammelCase for injected dependency

constructor(private persistenceService: PersistenceService ){}

<小时/>

您还可以使用 Arrow function 的 ES6 之美，而不是使用 .bind(this)

this.shaObj.generateIdentity().then((result, PersistenceService) => {
  //Assuming you changed dependency name to `persistenceService`
  console.log(this.persistenceService.set('identityKey'));
});