How to display json object using *ngFor

Question

I want to display the below data from Firebase

{
   "-KBN9O_qqz-nZ9tPWFdM":{
      "createdAt":1456399292790,
      "isActive":true,
      "name":"Hero 1"
   },
   "-KBN9gjJw1ZlMgt9pVsl":{
      "createdAt":1456399371220,
      "isActive":true,
      "name":"Hero 2"
   },
   "-KBN9hYI4vYAsyh5k1lX":{
      "createdAt":1456399374548,
      "isActive":true,
      "name":"Hero 3"
   }
}

when doing angular.io Tour of Heroes tutorial for example

<li *ngFor="#hero of heroes">
  <span class="badge">{{hero.id}}</span> {{hero.name}}
</li>

So hero id should show for example -KBN9hYI4vYAsyh5k1lX and hero name should show for example hero 3

---

I have done some research and come across this stackoverflow solution by @Thierry Templier access key and value of object using *ngFor

(1) Is this the right solution to my problem?

(2) Is there a simpler solution to this problem because I feel that it would be really common for developers using Angular2 to display such json data.

Answer 1

You need to implement a custom pipe to do this. ngFor only supports array and not object.

This pipe will look like that:

@Pipe({name: 'keys'})
export class KeysPipe implements PipeTransform {
  transform(value, args:string[]) : any {
    let keys = [];
    for (let key in value) {
      keys.push({key: key, value: value[key]});
    }
    return keys;
  }
}

and use it like that:

<span *ngFor="#entry of content | keys">           
  Key: {{entry.key}}, value: {{entry.value}}
</span>

See this question for more details:

• access key and value of object using *ngFor

Answer 2

Firebase id is called $.key. Also, # is now changed to let. This would work for you:

<li *ngFor="let hero of heroes">
  <span class="badge">{{hero.$key}}</span> {{hero.name}}
</li>

Answer 3

You can put the keys in an array and ng-repeat the keys.

export class IterateOverObject {
    public arrayOfKeys;

    @Input heros;
    constructor() {
        this.arrayOfKeys = Object.keys(this.heros);
    }
}

<li *ngFor="#key of arrayOfKeys">
  <span class="badge">{{key}}</span> {{heros[key].name}}
</li>

This looks simple to me.. More info is here