Grails - Domain object doesn't validate correctly

I'm trying to set the date of birth of a person using jQuery Datepicker. However, all I get is that the Property dateOfBirth must be a valid Date.

So, originally, my controller looks like this:

def update(Person personInstance) {
    if (personInstance == null) {
        // do Something
        return
    }

    if (personInstance.hasErrors()) {
        respond personInstance.errors, view: 'edit'
        return
    }

    // do the rest
}

I figured out, that with jQuery I should use a SimpleDateFormat object in order to generate a proper Date object. Nevertheless, even if I directly assign a new Date object to dateOfBirth and subsequently validating the personInstance domain object - like in the following code segment - I still get the Property dateOfBirth must be a valid Date error.

def update(Person personInstance) {
    if (personInstance == null) {
        // do Something
        return
    }

    // added code
    personInstance.dateOfBirth = new Date()
    personInstance.validate()
    // added code

    if (personInstance.hasErrors()) {
        respond personInstance.errors, view: 'edit'
        return
    }

    // do the rest
}

Thank you for any help :)

The reason why you are still seeing errors is because validation is automatically called after binding your command/domain object when the method is called.

Use personInstance.clearErrors() before calling personInstance.validate() manually to clear out any existing binding/validation errors. You can see more about this in the documentation.