我目前正在为angular应用程序实现基本服务。这应该为其他服务提供方法，以便使用默认标头和默认选项组成请求。当我尝试调用get或post方法时，会发生问题。这些方法仅调用this.request，但是出现此错误，我得到了ZoneAwarePromise。
ERROR Error: Uncaught (in promise): Cannot read property 'request' of undefined
at resolvePromise (zone.js:831)
at zone.js:896
at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:423)
at Object.onInvokeTask (core.js:17280)
at ZoneDelegate.push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invokeTask (zone.js:422)
at Zone.push../node_modules/zone.js/dist/zone.js.Zone.runTask (zone.js:195)
at drainMicroTaskQueue (zone.js:601)
at ZoneTask.push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask [as invoke] (zone.js:502)
at invokeTask (zone.js:1744)
at HTMLButtonElement.globalZoneAwareCallback (zone.js:1770)
defaultErrorLogger @ core.js:15714
push../node_modules/@angular/core/fesm5/core.js.ErrorHandler.handleError @ core.js:15762
next @ core.js:17761
schedulerFn @ core.js:13505
push../node_modules/rxjs/_esm5/internal/Subscriber.js.SafeSubscriber.__tryOrUnsub @ Subscriber.js:192
push../node_modules/rxjs/_esm5/internal/Subscriber.js.SafeSubscriber.next @ Subscriber.js:130
push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber._next @ Subscriber.js:76
push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next @ Subscriber.js:53
push../node_modules/rxjs/_esm5/internal/Subject.js.Subject.next @ Subject.js:47
push../node_modules/@angular/core/fesm5/core.js.EventEmitter.emit @ core.js:13489
(anonymous) @ core.js:17311
push../node_modules/zone.js/dist/zone.js.ZoneDelegate.invoke @ zone.js:391
push../node_modules/zone.js/dist/zone.js.Zone.run @ zone.js:150
push../node_modules/@angular/core/fesm5/core.js.NgZone.runOutsideAngular @ core.js:17248
onHandleError @ core.js:17311
push../node_modules/zone.js/dist/zone.js.ZoneDelegate.handleError @ zone.js:395
push../node_modules/zone.js/dist/zone.js.Zone.runGuarded @ zone.js:164
_loop_1 @ zone.js:694
api.microtaskDrainDone @ zone.js:703
drainMicroTaskQueue @ zone.js:608
push../node_modules/zone.js/dist/zone.js.ZoneTask.invokeTask @ zone.js:502
invokeTask @ zone.js:1744
globalZoneAwareCallback
这显然是没有意义的，因为我尝试在post方法内部调用this.request之前记录它的值，并且浏览器显示this.request存在。
interface Options {
payload?: any,
headers?: any,
options?: any
}
@Injectable()
export class ApiService {
private host: string = `${environment.apiUrl}`;
constructor(private http: HttpClient) {}
public get(route: string, options?: any) {
return this.request(route, 'GET', options);
}
public post(route: string, options?: any) {
return this.request(route, 'POST', options); // <- this line here
}
public setToken(token: string) {
localStorage.setItem('Token', token);
}
public unsetToken() {
localStorage.removeItem('Token');
}
private request(route: string, method: string, requestOptions?: any): Promise<void> {
return new Promise((resolve, reject) => {
const url = new URL(route, this.host);
const fn = this.http[method.toLowerCase()];
const { payload, headers, options }: Options = requestOptions || {};
const defaultHeaders = { 'Content-Type': 'application/json' };
const token = localStorage.getItem('Token');
if(token) defaultHeaders['Authorization'] = token;
const optionsDefinition = {
...options,
withCredentials: true,
headers: new HttpHeaders({...defaultHeaders, ...headers})
};
fn(url.toString(), payload, optionsDefinition)
.subscribe(() => {console.log('resolve'); resolve()},
() => {console.log('reject');reject() });
});
}
}
我希望在不出现此错误的情况下调用request方法。有人可以帮我吗？
编辑
我在以下login方法内调用post方法：
@Injectable()
export class AuthService {
private user: any = null;
constructor(private service: ApiService) {
console.log(service);
service.get('/api/users/current')
.then(user => this.user = user)
.catch(service.unsetToken);
}
login(username: string, password: string): Promise<void> {
const options: any = {
options: { responseType: 'text' },
payload: { username, password },
};
return new Promise((resolve, reject) => {
const onSuccess = response => {
this.service.setToken(response);
resolve();
};
const onFailure = error => {
reject(error.message);
};
this.service.post('/api/auth', options)
.then(onSuccess)
.catch(onFailure);
});
}
logout(): Promise<void> {
return new Promise((resolve, reject) => {
this.service.unsetToken();
resolve();
});
}
checkTokenValidity(): Promise<boolean> {
return new Promise((resolve, reject) => {
this.service.get('/api/auth/validity')
.then(() => resolve(true))
.catch(() => resolve(false));
});
}
public getUser() {
return { ...this.user };
}
}
答案 0 :(得分：0)
this 的值取决于函数的调用方式（运行时 绑定）。
内部对http对象使用http post方法调用“ request”方法，但是当您获得post引用并对其进行调用时，在严格模式下 此 引用将变得未定义
您可以直接使用http对象
private request(route: string, method: string, requestOptions?: any): Promise<void> {
return new Promise((resolve, reject) => {
const url = new URL(route, this.host);
const { payload, headers, options }: Options = requestOptions || {};
const defaultHeaders = { 'Content-Type': 'application/json' };
const token = localStorage.getItem('Token');
if(token) { defaultHeaders['Authorization'] = token; }
const optionsDefinition = {
...options,
withCredentials: true,
headers: new HttpHeaders({...defaultHeaders, ...headers})
};
this.http[method.toLowerCase()](url.toString(), payload, optionsDefinition)
.subscribe(() => {console.log('resolve'); resolve();},
() => {console.log('reject');reject(); });
});
}
另一种方法是使用bind方法修复此对象
const fn = this.http[method.toLowerCase()].bind(this.http);