Angular 2 dev extreme dx-date-box validation of required field

问题

I'm trying to use dx-date-box for date inputs but I can't make it validate required values on my form:

<dx-date-box placeholder="Request Date" required="true"
          formControlName="request_date" type="date" validationMessageMode="always" invalidDateMessage="{{VALIDATION.DATE_INVALID}}">
        </dx-date-box>

Invalid date validation is working and it shows the message, but it wont to validate required value and doesn't show required error. I'm not sure how to achieve that behaviour.

回答1:

I found this code from DevExtreme Documentation

Add dx-validator="dobValidationRules" to element and in angularJS, define dobValidationRules.

$scope.dobValidationRules = {
        validationRules: [{
            type: "required",
            message: "Date of birth is required"
        }, {
            type: "range", 
            max: maxDate, 
            message: "You must be at least 21 years old"
        }]
    };

Please find the actual working version here

来源：https://stackoverflow.com/questions/43503999/angular-2-dev-extreme-dx-date-box-validation-of-required-field