检查可观察对象时如何避免未定义？

Question

我正在MYPROFILE（）方法（此生成代码的方法）中使用hasProfile变量来检查用户是否具有个人资料（当他看到自己的个人资料时），并且hasProfile变量将显示一个用于创建的按钮当用户没有一个新的配置文件时。问题在于它正在获取和未定义的值，因为该变量位于可观察变量之内，甚至不评估If或console.log（'hasProfile1 ??? ::'，this.hasProfile）;。当我放一个。

所以问题是，如何在检查可观察对象时避免未定义？有其他实现目标的方法的想法吗？

如果我添加this.hasProfile = true;在方法开始时，即使res.body为空，变量也不会改变。

import { Component, OnInit, OnDestroy } from '@angular/core';
import { HttpErrorResponse, HttpHeaders, HttpResponse } from '@angular/common/http';
import { ActivatedRoute, Router } from '@angular/router';
import { Subscription } from 'rxjs';
import { JhiEventManager, JhiParseLinks, JhiAlertService, JhiDataUtils } from 'ng-jhipster';

import { IProfile } from 'app/shared/model/profile.model';
import { Principal } from 'app/core';

import { ITEMS_PER_PAGE } from 'app/shared';
import { ProfileService } from './profile.service';

@Component({
    selector: 'jhi-profile',
    templateUrl: './profile.component.html'
})
export class ProfileComponent implements OnInit, OnDestroy {

currentAccount: any;
profiles: IProfile[];
error: any;
success: any;
eventSubscriber: Subscription;
routeData: any;
links: any;
totalItems: any;
queryCount: any;
itemsPerPage: any;
page: any;
predicate: any;
previousPage: any;
reverse: any;
owner: any;
isAdmin: boolean;
hasProfile: boolean;

constructor(
    private profileService: ProfileService,
    private parseLinks: JhiParseLinks,
    private jhiAlertService: JhiAlertService,
    private principal: Principal,
    private activatedRoute: ActivatedRoute,
    private dataUtils: JhiDataUtils,
    private router: Router,
    private eventManager: JhiEventManager
) {
    this.itemsPerPage = ITEMS_PER_PAGE;
    this.routeData = this.activatedRoute.data.subscribe(data => {
        this.page = data.pagingParams.page;
        this.previousPage = data.pagingParams.page;
        this.reverse = data.pagingParams.ascending;
        this.predicate = data.pagingParams.predicate;
    });
}

loadAll() {
    this.profileService
        .query({
            page: this.page - 1,
            size: this.itemsPerPage,
            sort: this.sort()
        })
        .subscribe(
            (res: HttpResponse<IProfile[]>) => this.paginateProfiles(res.body, res.headers),
            (res: HttpErrorResponse) => this.onError(res.message)
        );
}

loadPage(page: number) {
    if (page !== this.previousPage) {
        this.previousPage = page;
        this.transition();
    }
}

transition() {
    this.router.navigate(['/profile'], {
        queryParams: {
            page: this.page,
            size: this.itemsPerPage,
            sort: this.predicate + ',' + (this.reverse ? 'asc' : 'desc')
        }
    });
    this.loadAll();
}

clear() {
    this.page = 0;
    this.router.navigate([
        '/profile',
        {
            page: this.page,
            sort: this.predicate + ',' + (this.reverse ? 'asc' : 'desc')
        }
    ]);
    this.loadAll();
}

ngOnInit() {
    this.loadAll();
    this.principal.identity().then(account => {
        this.currentAccount = account;
        this.owner = account.id;
        this.principal.hasAnyAuthority(['ROLE_ADMIN']).then( result => {
            this.isAdmin = result;
        });
    });
    this.registerChangeInProfiles();
}

ngOnDestroy() {
    this.eventManager.destroy(this.eventSubscriber);
}

trackId(index: number, item: IProfile) {
    return item.id;
}

byteSize(field) {
    return this.dataUtils.byteSize(field);
}

openFile(contentType, field) {
    return this.dataUtils.openFile(contentType, field);
}

registerChangeInProfiles() {
    this.eventSubscriber = this.eventManager.subscribe('profileListModification', response => this.loadAll());
}

sort() {
    const result = [this.predicate + ',' + (this.reverse ? 'asc' : 'desc')];
    if (this.predicate !== 'id') {
        result.push('id');
    }
    return result;
}

private myProfile() {
    const query = {
            page: this.page - 1,
            size: this.itemsPerPage,
            sort: this.sort()
        };
    if ( this.currentAccount.id  != null) {
        query['userId.equals'] = this.currentAccount.id;
    }
    console.log('Estoy entrando en el observalbe:');
    this.profileService
        .query(query)
        .subscribe(
                (res: HttpResponse<IProfile[]>) => {
                    if ( !res.body ) {
                        this.hasProfile = false;
                    }
                    this.paginateProfiles(res.body, res.headers);
                } , (res: HttpErrorResponse) => this.onError(res.message)
        );
    console.log('hasProfile???:', this.hasProfile);
}

private paginateProfiles(data: IProfile[], headers: HttpHeaders) {
    this.links = this.parseLinks.parse(headers.get('link'));
    this.totalItems = parseInt(headers.get('X-Total-Count'), 10);
    this.queryCount = this.totalItems;
    this.profiles = data;
    console.log('OWNER', this.owner);
    console.log('isADMIN', this.isAdmin);
    console.log('PROFILES:', this.profiles);
}

private onError(errorMessage: string) {
    this.jhiAlertService.error(errorMessage, null, null);
}

}

谢谢