typescript 在 Angular 2、Ionic 2 中返回承诺值
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Returning a promise value in Angular 2, Ionic 2
提问by Arianule
I am familiarizing myself with Angular2, Ionic2 and maybe I am misunderstanding something but was hoping for assistance.
我正在熟悉 Angular2、Ionic2，也许我误解了一些东西，但希望得到帮助。
I have a provider called 'CurrentUser' for the purpose of storing and getting LocalStorage data.
我有一个名为“CurrentUser”的提供程序，用于存储和获取 LocalStorage 数据。
getProfile(): any {
this.local.get("user-profile").then((profile) => {
var val = JSON.parse(profile);
return val;
});
}
this function getProfile()returns a promise
这个函数getProfile()返回一个承诺
If I inject this provider into a component. How would I await the promise to to resolve before assigning the data when calling this function from the component?.
如果我将此提供程序注入到组件中。从组件调用此函数时，如何在分配数据之前等待解决的承诺？
@Component({
templateUrl: 'build/pages/book_meeting/book_meeting.html'
})
export class BookMeetingPage implements OnInit {
constructor(public navCtrl: NavController, private _currentUser: CurrentUser) {
}
profile: IProfile;
ngOnInit(): any {
this.profile = this._currentUser.getProfile();
console.log(this.profile);//returns undefined
}
}
回答by Pankaj Parkar
First of all you have to return this.local.get("user-profile")promise from getProfilefunction so that it can chain when you call. Thereafter you can get data returned from getProfilefunction in .thensuccess callback.
首先，您必须this.local.get("user-profile")从getProfile函数返回承诺，以便在您调用时可以链接。此后，您可以getProfile在.then成功回调中获取从函数返回的数据。
getProfile(): any {
return this.local.get("user-profile").then((profile) => {
var val = JSON.parse(profile);
return val;
});
);
Additionally you can't get data as soon as you make an ajax, on success of it you can get the response
此外，您无法在制作 ajax 后立即获取数据，成功后您可以获得响应
ngOnInit(): any {
this._currentUser.getProfile().then(
value => { console.log(value) }
)
}
回答by Omri L
Your function getProfile doesn't return a promise. It returns nothing. You should change it to
您的函数 getProfile 不返回承诺。它什么都不返回。你应该把它改成
getProfile(): any {
return this.local.get("user-profile").then((profile) => {
var val = JSON.parse(profile);
return val;
});
Now in your component, you can extract the data from your profile promise variable.
现在在您的组件中，您可以从配置文件承诺变量中提取数据。
ngOnInit(): any {
this._currentUser.getProfile().then(value => {
console.log(value); //returns your value.
}
