How to validate all Angular form fields?

Question

Angular

I am using template driven form:

<form #documentForm="ngForm" autocomplete="off">
     <mat-form-field>
                    <mat-label>{{ fieldDefinition.title }}</mat-label>
                    <input
                        matInput
                        type="text"
                        name="{{ elementName }}"
                        #ref="ngModel"
                        [required]="fieldDefinition.isrequired"
                        [pattern]="fieldDefinition.mask"
                        [(ngModel)]="fieldDefinition.value"
                    />

                    <mat-error *ngIf="ref.touched && ref.invalid">
                        {{ fieldDefinition.maskdef }}
                    </mat-error>
                </mat-form-field>
</form>

How to validate all fields on button click and show tooltips for required and pattern if fields are invalid?