ionic 2 returns {"__ zone_symbol__state":null,"__ zone_symbol__value":"cyprus"}

Question

我在一个名为api-serive.ts的提供者页面中有我的功能

//get city in profile 
    getCityInProfile(){
        return new Promise((resolve, reject) => {

            let headers = new Headers({ 'Authorization':  
             localStorage.getItem('token') });

            this.http.get(this.getProfile,{headers:headers}).subscribe(
                (res) => {
                    console.log (res.json().profile.location)
                    resolve(res.json().profile.location)
                    return  (resolve(res.json().profile.location));
                },(err) => {
                    reject(err);
                }); 
        })

    }

当我在另一个page.ts中调用此函数来获取我的个人资料中的城市时,它会返回:

{ "__zone_symbol__state":空, "__ zone_symbol__value": "塞浦路斯"}

这就是我在page.ts中调用它的方式

CityInProfile(){console.log(JSON.stringify(this.jobsServiceProvider.getCityInProfile())+'return')this.cityProfile = this.jobsServiceProvider.getCityInProfile(); }

价值在那里(塞浦路斯),但为什么它会以这种方式返回

Answer 1

您必须记住,服务是以异步方式获取数据,因此您必须等待该数据准备就绪.

如果您不介意,我会对您的代码进行一些小的更改:

// Get city in profile 
getCityInProfile(): Promise<any> {

    // First get the token from the localStorage (it's async!)
    return localStorage.getItem('token').then(token => {

        // Set the token in the header
        let headers = new Headers({ 'Authorization':  token });

        // Make the request, but don't subscribe here!
        return this.http.get(this.getProfile, { headers:headers })
                        .map(res => res.json())
                        .map(resJson => resJson.profile.location)
                        .toPromise();

    });
}

然后,当您想要使用该服务时,您需要这样做:

public getCityInProfile(): void {

    // Use the 'then' to wait for the response to be ready
    this.jobsServiceProvider.getCityInProfile().then(city => {

        // Now you can use the city returned by the service
        console.log(`Returned: ${city}`);
        this.cityProfile = city;

    });

}