criterion.component.html

<div class="row">
    <div class="col form-group">
        <label>
            <app-attribute-label [label]="attribute.label" [description]="attribute.description"></app-attribute-label>
        </label>
        <ng-template searchType></ng-template>
    </div>
    <div class="col-2 text-center align-self-center">
        <select [disabled]="criterion != null" class="form-control" [(ngModel)]="nullOrNotNull" (change)="onChangeNull()">
            <option></option>
            <option value="nl">Null</option>
            <option value="nnl">Not null</option>
        </select>
    </div>
    <div class="col-2 text-center align-self-center">
        <button class="btn btn-outline-success" *ngIf="!criterion" [hidden]="!searchTypeComponent.isValid() && !nullOrNotNull" (click)="emitAdd()">
            <span class="fas fa-plus fa-fw"></span>
        </button>
        <button class="btn btn-outline-danger" *ngIf="criterion" (click)="deleteCriterion.emit(attribute.id)">
            <span class="fa fa-times fa-fw"></span>
        </button>
    </div>
</div>