在我看来它应该可以工作,但是我得到了一个模板错误: Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays.
模板:
<div class="block-header">
<h2>{{ policyName }}</h2>
</div>
<div *ngFor="let p of policies | async" class="card event-card">
<div class="card-header">
<h2>{{ p.title }}</h2>
</div>
<div class="card-body card-padding">
<div [markdown]="p.description"></div>
</div>
</div>
组件:
export class PoliciesComponent implements OnInit {
name: string = 'policies';
//public policies: Policy[];
public policies: Observable<Policy>;
constructor(
private policyService: PolicyService,
private route: ActivatedRoute) { }
ngOnInit(): void {
// this.route.params is an observable of the child (category) routes under /policies
this.route.params.subscribe((p: Params) => this.loadPolicies(p['category']))
}
loadPolicies(category: string): void {
let policyCategory = PolicyCategory.ClubPolicy;
if (category === 'rules') {
policyCategory = PolicyCategory.LocalRule;
} else if (category === 'handicaps') {
policyCategory = PolicyCategory.Handicaps;
}
this.policies = this.policyService.loadPolicies(policyCategory);
// this.policies = [];
// this.policyService.loadPolicies(policyCategory).subscribe(p => this.policies.push(p))
}
}
服务:
loadPolicies(category: PolicyCategory): Observable<Policy> {
return this.dataService.getApiRequest('policies')
.mergeAll() // turn Observable<any> where any=collection into Observable
.map((p: any) => new Policy().fromJson(p))
.filter((policy: Policy) => policy.category === category)
}
使用替换代码(在组件中的注释中),一切都起作用,但是我将不得不退订订阅。我觉得我正在做正确的事情,但是我的浏览器不同意。
我误解了异步如何与可观察的可观察到的?
问题的答案"我在误解什么?"是,太多了。
我认为,最重要的是,在尝试进行更具反应性的编程方式时,请理解服务的作用。它应该做的不仅仅是通过。
基于Cory Rylan的阅读帖子,我得出的结论是,我的服务应以不同的方式管理数据。末尾的概述部分尤其值得阅读。
因此,虽然我没有在原始帖子中重新设计服务,但我确实有一个很好的模式用于粗糙服务。该服务具有我的组件订阅的数据存储。该动作突变该数据存储,并在可观察物的奇迹中,当商店随着这些操作而更改时,它们会自动更新。
用您要管理的任何对象替换" profilerjob":
@Injectable()
export class ProfilerJobService {
private resource: string = 'profile';
private _jobs: BehaviorSubject<ProfilerJob[]>;
private store: {
items: ProfilerJob[]
};
constructor(private dataService: DataService) {
this.store = {
items: []
};
this._jobs = <BehaviorSubject<ProfilerJob[]>>new BehaviorSubject([]);
}
get jobs(): Observable<ProfilerJob[]> {
return this._jobs.asObservable();
}
selectJob(id: string): Observable<ProfilerJob> {
if (id === 'new') {
return Observable.of(new ProfilerJob());
}
return this._jobs.map(jobs => {
let job = jobs.find(item => item.id === id);
return _.clone(job);
});
}
loadJobs(filter: JobFilter = null): void {
let url = this.resource;
let params: any;
if (filter) {
url = url + '/search';
params = filter.toSearchApi();
}
this.dataService.getData(url, params).subscribe(data => {
this.store.items.length = 0;
data.forEach((d: any) => this.store.items.push(new ProfilerJob().fromJson(d)));
this._jobs.next(_.cloneDeep(this.store).items);
});
}
loadJob(id: string): void {
this.dataService.getData(`${this.resource}/${id}`).subscribe(json => {
let found = false;
this.store.items.forEach((item, index) => {
if (item.id === json.id) {
this.store.items[index] = new ProfilerJob().fromJson(json);
found = true;
}
});
if (!found) {
this.store.items.push(new ProfilerJob().fromJson(json));
}
this._jobs.next(_.cloneDeep(this.store).items);
});
}
addJob(job: ProfilerJob): Observable<void> {
return this.dataService.postData(this.resource, job.toJson())
.do((json: any) => {
this.loadJob(json.id);
});
}
updateJob(job: ProfilerJob): Observable<void> {
return this.dataService.putData(`${this.resource}/${job.id}`, job.toJson())
.do(() => {
this.loadJob(job.id);
});
}
deleteJob(job: ProfilerJob): Observable<void> {
return this.dataService.deleteData(`${this.resource}/${job.id}`)
.do(() => {
let idx = this.store.items.findIndex(j => j.id === job.id);
this.store.items.splice(idx, 1);
this._jobs.next(_.cloneDeep(this.store).items);
});
}
}