当我打开网页时,数据会被显示出来,但当我改变组件并回到该组件时,该组件的数据不会被显示。它会显示"无项目"。我检查了日志,但没有运行到ngOnIt。ngOnIt在Web启动或Web重新加载时运行。
这是stock.service.ts文件。
这是stock.service.ts文件。
import { Injectable } from '@angular/core';
import { AngularFirestore, AngularFirestoreCollection, AngularFirestoreDocument } from 'angularfire2/firestore';
import { Observable } from 'rxjs/Observable';
import { Stock } from './stock.model';
@Injectable()
export class StockService {
stocksCollection: AngularFirestoreCollection<Stock>;
stocks: Observable<Stock[]>;
constructor(public afs: AngularFirestore) {
this.stocks = this.afs.collection('stocks').valueChanges();
}
getStock(){
return this.stocks;
}
}
stock.component.ts
import { Component, OnInit, Input } from '@angular/core';
import { ActivatedRoute,Params } from '@angular/router';
import { StockService } from '../shared/stock.service';
import { Stock } from '../shared/stock.model';
import { Brands } from '../shared/brand';
import { Subscription } from 'rxjs/Subscription';
@Component({
selector: 'app-stock',
templateUrl: './stock.component.html',
styleUrls: ['./stock.component.css']
})
export class StockComponent implements OnInit {
stocks: Stock[];
brand: Brands;
sub: Subscription;
brand_name: string;
constructor(
private stockService: StockService,
private router: ActivatedRoute
) { }
ngOnInit() {
this.stockService.getStock().subscribe(stocks => {
console.log(stocks);
this.stocks = stocks;
});
this.sub = this.router.params.subscribe(params =>{
this.brand_name = params['brand'];
});
console.log('Brand : '+this.brand_name);
}
}
以及 stock.component.html
<div *ngIf="stocks != null || stocks?.length > 0 ; else noStocks" >
<ul *ngFor="let item of stocks" class="collection">
<li class="collection-item " >{{item.name}} | {{item.brand}} | {{item.price}}</li>
</ul>
</div>
<ng-template #noStocks>
<p>no item</p>
</ng-template>
我不知道代码哪里出错了。谢谢您的回答。