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[英]Uncaught (in promise): TypeError: Cannot read property 'userSubject' of undefined TypeError: Cannot read property 'userSubject' of undefined
[英]Uncaught (in promise): TypeError: Cannot read property 'router' of undefined
我正在嘗試使用Firebase服務更新/編輯資源,並且在更新/編輯后,我想將其發送回列表組件。
this.firebaseService.updateListing(this.id, listing).then(function() {
this.router.navigate(['/listing/'+this.id]);
});
當我使用foll代碼時,它可以工作,但是我想弄清楚以上原因為什么不起作用。 任何幫助將不勝感激。
this.firebaseService.updateListing(this.id, listing);
this.router.navigate(['/listings']);
愚弄是我第一種方法得到的錯誤:
Uncaught (in promise): TypeError: Cannot read property 'router' of undefined
路線是我的路線:
const appRoutes: Routes = [
{path:'', component:HomeComponent},
{path: 'listings', component:ListingsComponent},
{path: 'listing/:id', component:ListingComponent},
{path: 'edit-listing/:id', component:EditListingComponent},
{path: 'add-listing', component:AddListingComponent}
]
這就是我的EditListingComponent代碼
export class EditListingComponent implements OnInit {
id:any;
checklist:any; /*ngmodel binds the html fields to the properties in the component*/
notes:any;
constructor(private firebaseService: FirebaseService, private router:Router, private route:ActivatedRoute) { }
ngOnInit() {
// Get ID
this.id = this.route.snapshot.params['id'];
this.firebaseService.getListingDetails(this.id).subscribe(listing => {
this.checklist = listing.checklist;
this.notes = listing.notes;
console.log(listing);
});
}
onEditSubmit(){
let listing = {
checklist: this.checklist,
notes: this.notes
}
this.firebaseService.updateListing(this.id, listing).then(function() {
this.router.navigate(['/listing/'+this.id]);
});
/*this.firebaseService.updateListing(this.id, listing);
this.router.navigate(['/listings']);
}
}
我已經看過其他與此類似的問題,但是在回答我的問題之前,我不確定這是否與“ this”的上下文有關。
回調內部的this
參數與外部的參數不同。 因此,您基本上有兩個選擇:
1)添加this
的引用:
let self = this;
this.firebaseService
.updateListing(this.id, listing)
.then(function() {
self.router.navigate(['/listing/'+this.id]);
});
2)使用箭頭函數(不保留當前this
情況下):
this.firebaseService
.updateListing(this.id, listing)
.then(() => {
this.router.navigate(['/listing/'+this.id]);
});
嘗試在上下文中添加this
:
this.firebaseService.updateListing(this.id, listing).then(function() {
this.router.navigate(['/listing/'+this.id]);
}, this); /* <-- here */
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