Validate TextField

Hi
I would like to create simple edit form for text and double values.

For text field I'm using RegExpValidator:

Code:

---

TextField {
                id: itemNazwa
                width: 200
                height: 20
                focus: true
                maximumLength: 30
                validator: RegExpValidator { regExp: /[0-9a-fA-F\s]{1,30}/; }
            }

---

and for double value I'm using DoubleValidator:

Code:

---

TextField {
                id: itemCenaNetto
                width: 200
                height: 20
                text: qsTr("---")
                validator: DoubleValidator { bottom: 0; top: 1e10; decimals: 2; }
            }

---

What I found out is that validator is working only when text field is empty and user starts to input some text. If there is already some text in text input field validators are not working, user is able to input any values into text field.

I would like to set current values on form load and allow user to edit those values in validated fields. How to correctly implement input form with validation?