刷新頁面後爲什麼我的項目被更改？

的.html

<ion-header> 
    <ion-navbar color="secondary"> 
    <ion-title>Reviews</ion-title> 
    <ion-buttons end> 
     <button ion-button icon-only (click)="addReview()"> 
     <ion-icon name="add"></ion-icon> 
     </button> 
    </ion-buttons> 
    </ion-navbar> 
</ion-header> 

<ion-content> 
    <ion-list no-lines> 
    <ion-item-sliding *ngFor="let review of reviews"> 
     <ion-item> 
     <ion-avatar item-left> 
      <img src="https://api.adorable.io/avatars/75/{{review.title}}"> 
     </ion-avatar> 
     <h2>{{review.title}}</h2> 
     <p>{{review.description}}</p> 
     <ion-icon *ngIf="review.rating < 50" danger name="sad"></ion-icon> 
     <ion-icon *ngIf="review.rating >= 50" secondary name="happy"></ion-icon> 
     {{review.rating}} 
     </ion-item> 
    </ion-item-sliding> 
    </ion-list> 
</ion-content>

.TS

import { Component } from '@angular/core'; 
import { NavController, ModalController } from 'ionic-angular'; 
import { Reviews } from '../../providers/reviews'; 
import { AddReviewPage } from '../add-review-page/add-review-page'; 


@Component({ 
    selector: 'page-home', 
    templateUrl: 'home.html' 
}) 
export class HomePage { 
    reviews: any; 
    constructor(public navCtrl: NavController, public reviewService: Reviews, public modalCtrl: ModalController) { 

    } 
    ionViewDidLoad() { 
    this.reviewService.getReviews().then((data) => { 
     console.log(data); 
     this.reviews = data; 
    }); 

    } 

    addReview() { 

    let modal = this.modalCtrl.create(AddReviewPage); 
    modal.onDidDismiss(review => { 
     if (review) { 
     this.reviews.push(review); 
     // console.log('inside modal',review); 
     this.reviewService.createReviews(review); 
     } 
    }); 
    modal.present(); 

    } 



}

.providers

import { Injectable } from '@angular/core'; 
import { Http,HttpModule } from '@angular/http'; 
import 'rxjs/add/operator/map'; 

/* 
    Generated class for the Reviews provider. 

    See https://angular.io/docs/ts/latest/guide/dependency-injection.html 
    for more info on providers and Angular 2 DI. 
*/ 
@Injectable() 
export class Reviews { 

    data: any; 

    constructor(public http: Http) { 
    console.log('Hello Reviews Provider'); 
    this.data = null; 
    } 

    getReviews() { 
    if (this.data) { 
     return Promise.resolve(this.data); 
    } 
    return new Promise(resolve => { 
     this.http.get('http://localhost:8080/api/reviews').map(res => res.json()).subscribe(data => { 
     this.data = data; 
     resolve(this.data); 
     }); 
    }); 
    } 

    createReviews(review){ 
    this.http.post('http://localhost:8080/api/reviews',JSON.stringify(review)).subscribe(res=>{ 
     console.log('inside create review', res.json()); 
    }) 

    } 
}

當我添加數據，項目用不同的化身添加成功。但是，當我刷新頁面的項目被刪除和ava焦油得到改變，爲什麼呢？下面提供了屏幕截圖。