Angular2 : How to subscribe to Http. post observable inside a service and a component properly？

Question

对于 JWT 身份验证，我现在使用与 Observables 一起使用的新 Http 模块发出请求以获取 token 。

我有一个简单的 Login 组件显示表单:

@Component({
selector: 'my-login',
    template: `<form (submit)="submitForm($event)">
                <input [(ngModel)]="cred.username" type="text" required autofocus>
                <input [(ngModel)]="cred.password" type="password" required>
                <button type="submit">Connexion</button>
            </form>`
})
export class LoginComponent {
    private cred: CredentialsModel = new CredentialsModel();

    constructor(public auth: Auth) {}

    submitForm(e: MouseEvent) {
        e.preventDefault();
        this.auth.authentificate(this.cred);
    }
}

我有一个 Auth 服务发出请求:

@Injectable()
export class Auth {
    constructor(public http: Http) {}

    public authentificate(credentials: CredentialsModel) {
        const headers = new Headers();
        headers.append('Content-Type', 'application/json');

        this.http.post(config.LOGIN_URL, JSON.stringify(credentials), {headers})
            .map(res => res.json())
            .subscribe(
                data => this._saveJwt(data.id_token),
                err => console.log(err)
            );
    }
}

效果很好，但现在我想在我的组件中显示错误消息，所以我需要在 2 个地方订阅(Auth 用于管理成功，Login 用于管理错误)。

我使用 share 运算符实现了它:

public authentificate(credentials: CredentialsModel) : Observable<Response> {
    const headers = new Headers();
    headers.append('Content-Type', 'application/json');

    const auth$ = this.http.post(config.LOGIN_URL, JSON.stringify(credentials), {headers})
                            .map(res => res.json()).share();

    auth$.subscribe(data => this._saveJwt(data.id_token), () => {});

    return auth$;
}

在组件内部:

submitForm(e: MouseEvent) {
    e.preventDefault();
    this.auth.authentificate(this.cred).subscribe(() => {}, (err) => {
        console.log('ERROR component', err);
    });
}

它有效，但我觉得做错了..我只是转换了我们用 angular1 和 promises 做的方式，你有没有更好的实现方式？

Answer 1

当可以使用这种方法时，为什么要在 sharedService 中订阅!

@Injectable()
export class Auth {
    constructor(public http: Http) {}

    public authentificate(credentials: CredentialsModel) {
        const headers = new Headers();
        headers.append('Content-Type', 'application/json');

            return  this.http.post(config.LOGIN_URL, JSON.stringify(credentials), {headers})      //added return
            .map(res => res.json());
            //.subscribe(
            //    data => this._saveJwt(data.id_token),
            //    err => console.log(err)
            //);
    }
}

---

@Component({
selector: 'my-login',
    template: `<form (submit)="submitForm($event)">
                <input [(ngModel)]="cred.username" type="text" required autofocus>
                <input [(ngModel)]="cred.password" type="password" required>
                <button type="submit">Connexion</button>
            </form>`
})
export class LoginComponent {
    private cred: CredentialsModel = new CredentialsModel();

    constructor(public auth: Auth) {}

    submitForm(e: MouseEvent) {
        e.preventDefault();
        this.auth.authentificate(this.cred).subscribe(
               (data) => {this.auth._saveJwt(data.id_token)},  //changed
               (err)=>console.log(err),
               ()=>console.log("Done")
            );
    }
}

---

编辑
如果您想在 sharedService 和 component 中订阅，您当然可以采用这种方法. 但我不推荐这个，而是在编辑部分对我来说很完美之前。

我无法使用您的代码对其进行测试。但看看我的example here(tested) .单击 myFriends 选项卡，检查浏览器控制台和 UI。浏览器控制台显示 sharedService 的订阅结果 & UI 显示 component 的订阅结果。

---

  @Injectable()
  export class Auth {
    constructor(public http: Http) {}

    public authentificate(credentials: CredentialsModel) {
        const headers = new Headers();
        headers.append('Content-Type', 'application/json');

           var sub =  this.http.post(config.LOGIN_URL, JSON.stringify(credentials), {headers})      //added return
            .map(res => res.json());

           sub.subscribe(
                data => this._saveJwt(data.id_token),
                err => console.log(err)
               );

           return sub;
    }
}

---

export class LoginComponent {
    private cred: CredentialsModel = new CredentialsModel();

    constructor(public auth: Auth) {}

    submitForm(e: MouseEvent) {
        e.preventDefault();
        this.auth.authentificate(this.cred).subscribe(
               (data) => {this.auth._saveJwt(data.id_token)},  //not necessary to call _saveJwt from here now.
               (err)=>console.log(err),
               ()=>console.log("Done")
            );
    }
}