NGX-CHIPS无法呈现Firebase返回的列表

时间:2019-05-21 02:27:58

标签: angular typescript firebase-realtime-database ngx-chips

我在Angular中使用NGX-Chips。我将键入的筹码保存到Firebase中并进行检索。

问题是,当它尝试呈现已保存的芯片时,它无法并引发错误。

在发布此问题之前,我尝试在GitHub上通读并关注此问题,并添加了displayByidentifyBy标签,但无济于事。

错误

Error: Error trying to diff '[object Object]'. Only arrays and iterables are allowed

HTML代码

<tag-input 
     (onAdd)="onCategoryAdded($event, product.external_id)" 
    [displayBy]="'display'"
    [identifyBy]="'$key'" 
    [(ngModel)]="product.categories"
    [ngModelOptions]="{standalone: true}"
    theme="minimal" 
    placeholder="Categories"
>
 <tag-input-dropdown [autocompleteItems]="categories"></tag-input-dropdown></tag-input>
</tag-input>

在我的控制器中,我设置了一个可观察项,侦听值更改并将这些更改分配给提及的可观察项。

public products: Observable<any[]>;

ngOnInit() {
   this.products = this.afd.list('/products').valueChanges();
}

onCategoryAdded(event, product) {
  this.afd.database.ref('/products').orderByChild('external_id').equalTo(product).once('value', (snapshot) => {
    snapshot.forEach((product) => {
      this.afd.database.ref('/products').child(product.key).child('categories').push({
        'display' : event.display,
        'value' : event.value
      });
    });
  });
}
当我在HTML中添加product.categories时,

{{product.categories | json}}如下打印。

{ "-LfN8VhSrWBye-8ukSAq": { "display": "Featured", "value": "Featured" } }

我应该更改在Firebase中保存类别的方式,以便它返回不同的值,还是应该在控制器内以某种方式转换返回的值?

1 个答案:

答案 0 :(得分:0)

正如错误NGX-CHIPS中所述,正在等待数组,并且您正在传递对象

Error: Error trying to diff '[object Object]'. Only arrays and iterables are allowed

您正在将其传递给NGX-CHIPS


{ "-LfN8VhSrWBye-8ukSAq": { "display": "Featured", "value": "Featured" } }

您需要将此json / object转换为数组,可以使用map运算符进行操作

// don't forget to import the operator

import { map } from 'rxjs/operators'


ngOnInit() {
   this.products = this.afd.list('/products').valueChanges().pipe(
map(list => {

      const productsArray = Object.keys(list).map(key => {
         const item = list[id]; // [{display: 'Featured', value: 'Featured'}]
         item.key = key;  // [{key: "-LfN8VhSrWBye-8ukSAq", display: 'Featured', value: 'Featured'}]
         return item;
      });

   }));
}