[英]Cannot assign to read only property 'winner' of object '[object Object]'
我遇到了錯誤
ContestDetailsModalComponent.html:21 ERROR TypeError: Cannot assign to read only property 'winner' of object '[object Object]'
at ContestDetailsModalComponent.onWinner (contest-details-modal.component.ts:88:24)
at Object.eval [as handleEvent] (ContestDetailsModalComponent.html:21:17)
at handleEvent (core.js:43993:77)
at callWithDebugContext (core.js:45632:1)
at Object.debugHandleEvent [as handleEvent] (core.js:45247:1)
at dispatchEvent (core.js:29804:1)
at core.js:42925:1
at HTMLButtonElement.<anonymous> (platform-browser.js:2668:1)
at ZoneDelegate.invokeTask (zone-evergreen.js:399:1)
at Object.onInvokeTask (core.js:39680:1)
當我嘗試做作業時
this.contest.winner = winnerId;
您在以下代碼片段中看到:
public onWinner(winnerId: number): void {
const post: Post = new Post();
post.title = `The winner of the contest has been elected: ${this.contest.title}`;
post.description = `Tizio has been elected winner of the contest and ${this.user.name} gives him the most welcome compliments`;
post.user = this.user;
post.contest = this.contest;
post.type = Type.WINNER;
post.level = Level.SUCCESS;
this.contest.winner = winnerId;
this.store.dispatch(PostActions.savePost({post}));
this.store.dispatch(ContestActions.saveContest({contest: this.contest}));
}
我和項目周圍的其他班級一起完成了這種作業,他們從來沒有打擾過我。
我附上比賽 class 並發布是否有用:
export class Contest {
public id: number;
public title: string;
public description: string;
public rules: string;
public startDate: Date;
public endDate: Date;
public status: Status;
public winner: number;
public bannedUser: number[];
}
export class Post {
public id: number;
public title: string;
public description: string;
public level: Level;
public type: Type;
public user: User;
public publishDate: Date;
public contest: Contest;
}
我還嘗試了一些總是在這個論壇上找到的解決方案,例如:
Object.assign(目標,來源);
但他正確地告訴我 this.contest.winner 是 null 或未定義。
我希望得到你的幫助。 謝謝
編輯:
這是存在 onWinner() 的整個 component.ts。
@Component({
selector: 'app-contest-details-modal',
templateUrl: './contest-details-modal.component.html',
styleUrls: ['./contest-details-modal.component.scss'],
})
export class ContestDetailsModalComponent implements OnInit, OnDestroy, AfterViewChecked {
private readonly subscriptions: Subscription = new Subscription();
public id: number;
public user: User;
public contest: Contest;
public images: Image[];
public hasVoted: boolean;
constructor(
private readonly bsModalRef: BsModalRef,
private readonly modalService: BsModalService,
private readonly store: Store<AppState>,
private cdRef: ChangeDetectorRef
) { }
public ngOnInit(): void {
this.subscriptions.add(this.store.pipe(select(AuthSelectors.getUser)).subscribe((user: User) => {
if (user) {
this.user = user;
}
}));
this.subscriptions.add(this.store.pipe(select(ContestSelectors.getById)).subscribe((contest: Contest) => {
if (contest) {
this.contest = contest;
}
}));
this.subscriptions.add(this.store.pipe(select(ImageSelectors.getImages)).subscribe((images: Image[]) => {
if (images.length) {
this.images = images;
}
}));
this.subscriptions.add(this.store.pipe(select(UserSelectors.check)).subscribe((ack: Ack) => {
if (ack) {
this.store.dispatch(AuthActions.updatedUser({userId: this.user.id}));
this.modalService.show(UploadImageModalComponent);
this.bsModalRef.hide();
}
}));
this.subscriptions.add(this.store.pipe(select(ImageSelectors.check)).subscribe((ack: Ack) => {
if (ack) {
this.bsModalRef.hide();
}
}));
}
public ngOnDestroy(): void {
this.store.dispatch(UserActions.clean());
this.store.dispatch(ContestActions.clean());
this.subscriptions.unsubscribe();
}
public onWinner(winnerId: number): void {
const post: Post = new Post();
post.title = `The winner of the contest has been elected: ${this.contest.title}`;
post.description = `Tizio has been elected winner of the contest and ${this.user.name} gives him the most welcome compliments`;
post.user = this.user;
post.contest = this.contest;
post.type = Type.WINNER;
post.level = Level.SUCCESS;
this.contest.winner = winnerId;
this.store.dispatch(PostActions.savePost({post}));
this.store.dispatch(ContestActions.saveContest({contest: this.contest}));
}
public onJoin(): void {
this.store.dispatch(UserActions.saveUser({idUser: this.user.id, id: this.contest.id}));
}
public onVote(image: Image): void {
let vote: number = image.vote;
vote = vote + 1;
this.store.dispatch(ImageActions.updateImage({photoId: image.id, votes: vote, userId: this.user.id}));
this.store.dispatch(AuthActions.updatedUser({userId: this.user.id}));
}
public isContain(contestId: number): boolean {
if (this.user.myContest) {
for (const i of this.user.myContest) {
if (contestId === i) {
return true;
}
}
}
return false;
}
public isImageVoted(id: number): boolean {
if (this.user.favouritePhoto) {
for (const imageVoted of this.user.favouritePhoto) {
if (id === imageVoted) {
this.hasVoted = true;
return true;
}
}
return false;
}
}
public onBan(image: Image): void {
this.modalService.show(BanModalComponent, {initialState : image});
this.bsModalRef.hide();
}
public isBan(contestId: number): boolean {
if (this.user.whereBanned) {
for (const contestBanned of this.user.whereBanned) {
if (contestId === contestBanned) {
return true;
}
}
return false;
}
}
public ngAfterViewChecked(): void {
this.cdRef.detectChanges();
}
}
contest
包含對 Observable emission 的引用,並且 Observables 發出的所有引用都是只讀的。 要么克隆contest
:
this.contest = { ...contest };
或者,更好的是,將其保留為 Observable 並按原樣使用它,通常通過async
pipe。此外,如果您使用的是 NgRx,則需要使用store.select()
:
this.contest$ = this.store.select(ContestSelectors.getById);
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.