Angular form display one error message at a time

Question

I am using Angular 6 and I have a form and inside that I have two fields Name and Display name. I have 3-4 validation on both the fields like required, pattern, min length, max length. I want to display only single error message at a time. How to achieve that?

Here is the sample code.

<mat-form-field required>
            <label for="attribute_name">Name</label>
            <input type="text"
                   required
                   matInput
                   [(ngModel)]="attribute.name"
                   name="name"
                   id="attribute_name"
                   #nameInput="ngModel"
                   [ngClass]="{'form-validation--error-border' : (nameInput?.errors && (nameInput?.dirty || nameInput?.touched)) || false}"
                   [minlength]="3"
                   [maxlength]="63"
                   [pattern]="[some pattern]" />
            <ul *ngIf="nameInput.errors && (nameInput.dirty || nameInput.touched)" class="form-validation form-validation--error">
                <li *ngIf="nameInput.errors.required">Name is required</li>
                <li *ngIf="nameInput.errors.minlength">Minimum length should be 3.</li>
                <li *ngIf="nameInput.errors.pattern">It should start with letter.</li>
            </ul>
        </mat-form-field>

Answer 1

You can try ngTemplate *ngIf, else

<ul *ngIf="nameInput.errors && (nameInput.dirty || nameInput.touched)" class="form-validation form-validation--error">
   <li *ngIf="nameInput.errors.required; else minLengthElem;">Name is required</li>
</ul>
   <ngTemplate #minLengthElem>   
    <li *ngIf="nameInput.errors.minlength; else patternElem;">Minimum length should be 3.</li>
  </ngTemplate>
  <ngTemplate #patternElem>
    <li *ngIf="nameInput.errors.pattern">It should start with letter.</li>
  </ngTemplate>