How to use umbraco datetime property editor

When I was using Umbraco datetime property editor, I met with a problem that the editor must be first time initialized with value, if I want to change the value later after the control is rendered, I have to use javascript.

Below pasted the code.

editor part:

 <umb-property property="ExpiryDate">
                        <umb-editor model="ExpiryDate"></umb-editor>
                    </umb-property>

the controller initialization part:

function buildDateTimePickerModel(alias, label, description, value) {
	        return {
	            editor: "Umbraco.DateTime",
	            label: label,
	            description: description,
	            hideLabel: false,
	            view: "datepicker",
	            alias: alias,
	            value: value,
	            validation: {
	                mandatory: false,
	                pattern: ""
	            },
	            config: {
	                dateFormat: "YYYY-MM-DD HH:mm:ss",
	                pickDate: true,
	                pickTime: true,
	                useSeconds: true
	            }
	        };
	    };
$scope.ExpiryDate = buildDateTimePickerModel('ExpiryDate', 'ExpiryDate', 'Enter the ExpiryDate', null);

　　so, this code will guarantee that at least you can see the control as soon as it is loaded, but, you can see, what if I have a asynchonous model that I need to apply to this control later? my current solution is to find the control by its id, and then apply value to it with formatters, all these stuffs are actually wrapped in an angular js controller, so, the setter method of the control would be:

$('#ExpiryDate').val($filter('date')($scope.CouponCode.ExpiryDate, 'yyyy-MM-dd hh:mm:ss'));

　　anywhere!