Angular: Cannot find a differ supporting object '[object Object]'

Question

Im following this tutorial. On the way to get list of users from api.github Im getting error:

Cannot find a differ supporting object '[object Object]'

I think its related to

 <ul>
 <li *ngFor = "#user of users">
 {{user | json}}
 </li>
 </ul>

In my code because before it there was no any error, and im unsure if data come from get request, just clicking didnt give any error, here is my code so far

@Component({
selector: 'router',
pipes : [],

template: `
<div>
<form [ngFormModel] = "searchform">
      <input type = 'text' [ngFormControl]= 'input1'/>
</form>
     <button (click) = "getusers()">Submit</button>
</div>
<div>
<ul>
    <li *ngFor = "#user of users">
    {{user | json}}
    </li>
</ul>
</div>
<router-outlet></router-outlet>
`,
directives: [FORM_DIRECTIVES]
})
export class router {
searchform: ControlGroup;
users: Array<Object>[];
input1: AbstractControl;

constructor(public http: Http, fb: FormBuilder) {
    this.searchform = fb.group({
        'input1': ['']
    })
    this.input1 = this.searchform.controls['input1']
}
getusers() {
    this.http.get(`https://api.github.com/
search/users?q=${this.input1.value}`)
        .map(response => response.json())
        .subscribe(
        data => this.users = data,
        error => console.log(error)
        )
}
}
bootstrap(router, [HTTP_PROVIDERS])

Answer 1

I think that the object you received in your response payload isn't an array. Perhaps the array you want to iterate is contained into an attribute. You should check the structure of the received data...

You could try something like that:

getusers() {
  this.http.get(`https://api.github.com/search/users?q=${this.input1.value}`)
    .map(response => response.json().items) // <------
    .subscribe(
      data => this.users = data,
      error => console.log(error)
    );
}

Edit

Following the Github doc (developer.github.com/v3/search/#search-users), the format of the response is:

{
  "total_count": 12,
  "incomplete_results": false,
  "items": [
    {
      "login": "mojombo",
      "id": 1,
      (...)
      "type": "User",
      "score": 105.47857
    }
  ]
}

So the list of users is contained into the items field and you should use this:

getusers() {
  this.http.get(`https://api.github.com/search/users?q=${this.input1.value}`)
    .map(response => response.json().items) // <------
    .subscribe(
      data => this.users = data,
      error => console.log(error)
    );
}

Answer 2

I received this error in my code because I'd not run JSON.parse(result).

So my result was a string instead of an array of objects.

i.e. I got:

"[{},{}]" 

instead of:

[{},{}]

---

import { Storage } from '@ionic/storage';
...
private static readonly SERVER = 'server';
...
getStorage(): Promise {
  return this.storage.get(LoginService.SERVER);
}
...
this.getStorage()
  .then((value) => {
     let servers: Server[] = JSON.parse(value) as Server[];
                   }
  );

Answer 3

Missing square brackets around input property may cause this error. For example:

Component Foo {
    @Input()
    bars: BarType[];
}

Correct:

<app-foo [bars]="smth"></app-foo>

Incorrect (triggering error):

<app-foo bars="smth"></app-foo>

Answer 4

Something that has caught me out more than once is having another variable on the page with the same name.

E.g. in the example below the data for the NgFor is in the variable requests. But there is also a variable called #requests used for the if-else

<ng-template #requests>
  <div class="pending-requests">
    <div class="request-list" *ngFor="let request of requests">
      <span>{{ request.clientName }}</span>
    </div>
  </div>
</ng-template>