離子2無法讀取未定義的屬性'新聞'

Question

export class HomePage { 
    public news:Object; 

    constructor(public navCtrl: NavController,public httpdata:HttpdataproviderProvider) { 
    this.news = {}; 
    this.getAllNews(); 
    } 
    getAllNews(){ 
    let url = 'some url'; 

    this.httpdata.httpPost(url,someData) //some custom provider 
    .then(function(data){ 
     console.log(this.news); 
     this.news = data; 
    }) 
    } 
} 

爲什麼我不能訪問新聞對象或將數據分配給新聞。它顯示「無法讀取屬性‘

Answer 1

變化的回調函數，這樣的’不確定的」的消息，所以將舉行的背景下（這）

this.httpdata.httpPost(url,someData) //some custom provider 
.then((data) => { 
    console.log(this.news); 
    this.news = data; 
}) 

，或者你可以存儲喜歡的上下文的參照這

getAllNews(){ 
    let url = 'some url'; 
    let self = this; 

    this.httpdata.httpPost(url,someData) //some custom provider 
    .then(function(data){ 
    console.log(self.news); 
    self.news = data; 
    }) 
}