问用什么代替ngModel？

EN

<mat-form-field>
    <mat-label>Genre</mat-label>
    <mat-select [(ngModel)]="selectedGenre" required formControlName="genre">
        <mat-option>--</mat-option>
        <mat-option *ngFor="let item of genre | keyvalue" [value]="item.key">{{ item.key }}</mat-option>
    </mat-select>
</mat-form-field>

<mat-form-field *ngIf="selectedGenre">
    <mat-label>Choose a Sub Genre</mat-label>
    <mat-select formControlName="subgenre">
        <mat-option *ngFor="let sub of genre.get(selectedGenre)" [value]="sub">{{ sub }}</mat-option>
    </mat-select>
</mat-form-field>

It looks like you're using ngModel on the same form field as formControlName.
Support for using the ngModel input property and ngModelChange event with
reactive form directives has been deprecated in Angular v6 and will be removed
in a future version of Angular.