我正在使用@ angular / http用于http调用(Observable)和NativeStorage库用于存储机制,即Promise。这就是我使用FromPromise将Promise功能“NativeStorage.getItem(”xxx“)”转换为Observable的原因。
我甚至不确定这是不是一个好习惯而且链条在“console.log(”HIT SUCCESSFULLY“)行中被打破;”并停止执行代码。
由于存储中没有名为“externalAccessToken”的项,因此在Promise中捕获异常null是正常的,但我不明白为什么它会在此之后停止执行。
直到现在,我已经尝试返回除null之外的其他内容并使用“Promise.reject()”导致“未处理的承诺拒绝”错误。
如何保持代码执行并点击Observable的catch函数
public getExternalAccessTokenFromStorage(): Observable<any> {
let externalAccessTokenPromise = NativeStorage.getItem('externalAccessToken');
let getExternalAccessTokenFromStorage: Observable<any> = Observable.fromPromise(externalAccessTokenPromise.then(x => x)
.catch(() => {
console.log("HIT SUCCESSFULLY");
return null
}));
return getExternalAccessTokenFromStorage.map(x => {
console.log("NOT HIT AT ALL");
return x;
}).catch(() => {
console.log("NOT HIT AT ALL");
return null;
});
}
public getUserInfo(): Observable<StoredUserModel> {
//Get External Access Token From LocalStorage
return this.getExternalAccessTokenFromStorage().flatMap((x: IExternalAccessTokenBindingModel) => {
return this.getAccessTokenFromStorage().flatMap((accessToken: AccessTokenModel) => {
console.log("NOT HIT AT ALL");
let headers = new Headers();
headers.append("Authorization", "Bearer " + accessToken.access_token);
headers.append("Content-Type", "application/json");
let options = new RequestOptions({ headers: headers });
var externalBindingModel = JSON.stringify(x);
return this.http.post(this.baseUrl + '/api/Account/ExternalUserInfo', externalBindingModel, options).map((res: Response) => {
//ADD USER INTO NATIVESTORAGE
this.addUserIntoStorage(res.json());
return res.json();
});
});
}).catch(x => {
return this.getAccessTokenFromStorage().flatMap((accessToken: AccessTokenModel) => {
console.log("NOT HIT AT ALL");
let headers = new Headers();
headers.append("Authorization", "Bearer " + accessToken.access_token);
let options = new RequestOptions({ headers: headers });
return this.http.get(this.baseUrl + '/api/Account/UserInfo', options).map((res: Response) => {
//ADD USER INTO NATIVESTORAGE
let user: StoredUserModel = res.json();
this.addUserIntoStorage(res.json());
return user;
});
}).catch(error => {
return null;
});
});
}
更新的问题:
我已删除Promise.catch并保留Observable.catch以捕获Observable中的未处理异常;
public getExternalAccessTokenFromStorage(): Observable<any> {
let externalAccessTokenPromise = NativeStorage.getItem('externalAccessToken');
let getExternalAccessTokenFromStorage: Observable<any> = Observable.fromPromise(externalAccessTokenPromise);
return getExternalAccessTokenFromStorage.map(x => {
return x;
}).catch(() => {
return null;
});
}
我收到以下错误;
答案 0 :(得分:3)
Catch
与编程中的try / catch
碰撞完全相同。
举几个例子:
try {
throw new Error('bang');
} catch(ex) {
// do nothing
}
console.log('I'm still reachable');
我们可以通过这样的可观察来重现上述内容:
let o = Observable.create((observer)=>{
observer.error(new Error('bang'));
}).catch(()=>{
// do nothing
});
o.subscribe(()=>{
console.log('I'm still reachable');
});
如果你想捕获并处理错误,但是后来阻止使用try / catch
执行下面的代码,你会这样做:
try {
throw new Error('bang');
} catch(ex) {
// do some logic here
throw ex;
}
console.log('I cannot be reached');
在可观察者中也是如此。您必须重新抛出错误或产生一个也失败的observable。
let o = Observable.create((observer)=>{
observer.error(new Error('bang'));
}).catch((ex)=>{
// do some logic here
return Observable.throw(ex);
});
o.subscribe(()=>{
console.log('I cannot be reached');
});
答案 1 :(得分:1)
问题是你正在捕捉,但没有处理错误。您将希望将错误抛出为Observable。
public getExternalAccessTokenFromStorage(): Observable<any> {
let externalAccessTokenPromise = NativeStorage.getItem('externalAccessToken');
let getExternalAccessTokenFromStorage: Observable<any> = Observable.fromPromise(externalAccessTokenPromise);
return getExternalAccessTokenFromStorage.map(x => {
return x;
}).catch((error: any) =>
Observable.throw(error.json().error || 'Server error');
);
}
然后,您可以以承诺的形式处理您的回复和错误:
this.getExternalAccessTokenFromStorage().subscribe(
res => console.log(res),
error => console.log(error));