title: '[object Object],[object Object]' for pipe 'AsyncPipe'
body: <p>i need to create autocomplete with angular material in angular 8 .</p>
  
  <p>now i using this code in ts file :</p>
  
  <pre><code> @Input() admins: User[];
    userGroupOptions: Observable&lt;User[]&gt;;
    filterFormFG: FormGroup;
    constructor(private utilService: UtilsService, private messageService: MessageService) {
      this.createForm();
      this.userGroupOptions = this.filterFormFG.get('createdByRefId').valueChanges
        .pipe(
          startWith(''),
          map(admin =&gt; admin ? this._filterStates(admin) : this.admins.slice())
        );
    }
  
    ngOnInit() {
      // tslint:disable-next-line: no-non-null-assertion
  
  
    }
  
    private _filterStates(value: string): User[] {
      const filterValue = value.toLowerCase();
  
      return this.admins.filter(state =&gt; state.fullname.toLowerCase().indexOf(filterValue) === 0);
    }
  </code></pre>
  
  <p>and using this in html file :</p>
  
  <pre><code>          &lt;mat-form-field class="example-full-width" appearance="outline"&gt;
                          &lt;input matInput [placeholder]="'MESSAGES.SENDER' | translate" aria-label="'MESSAGES.SENDER' | translate" [matAutocomplete]="auto"
                          formControlName="createdByRefId"&gt;
                          &lt;mat-autocomplete #auto="matAutocomplete"&gt;
                              &lt;mat-option *ngFor="let item of (admins | async)" [value]="item.firstName + ' ' +item.lastName"&gt;
                                 {{ item.firstName + ' '+ item.lastName | translate }}
                              &lt;/mat-option&gt;
                          &lt;/mat-autocomplete&gt;
                      &lt;/mat-form-field&gt;
  </code></pre>
  
  <p>but it show me this Error :</p>
  
  <blockquote>
    <p>ERROR Error: InvalidPipeArgument: '[object Object],[object Object]' for pipe 'AsyncPipe'
        at invalidPipeArgumentError (common.js:4800)</p>
  </blockquote>
  
  <p>whats the problem ? how can  i solve this problem ?????</p>