Eclipse Scout Neon on value set validation detect loop

Question

I want to validate fields dependencies with other field when current field has changed.

Basic idea is that if I have field A and fields B,C,D,E,... and there is some complex dependencies graph on those fields, I would like to have it solve like this :

When I set value A export form data (current state of form)
form data is send to scout server
on scout server dependencies graph is calculated and resolved (we get list in order)
call setters of fields in ordered list which "fix" form data
Import form data at the end.

My problem is that if I trigger this event in

 @Override
protected void execChangedValue() {
    // trigger export
    // trigger server validation
    // trigger import
}

I get

2016-06-03 13:31:28,468 WARN  scout-model-thread-22 o.e.s.rt.client.ui.form.fields.AbstractValueField - Loop detection in ...$FieldA with value 101191 [m4042 @   ]
java.lang.Exception: null

How to fix this?

I even have a problem that, if I get error back, I want to abort import and set old value back.

 @Override
protected void execChangedValue() {
    // trigger export
    // trigger server validation
    if (error) {
        setValueWithoutTrigger(oldValue)
    } else {
        // trigger import
    }
}

What is oldValue it doesn't matter, it could be null. (so reset value when error). Method setValueWithoutTrigger is same as setValue() but before set value it called this.setValueChangeTriggerEnabled(false);

I know it somehow could be done, because I saw similar functionality in BSI code.

I don't get the point. As far as I understand, you want to calculate the values of fields B, C, D, and E on the server. Why would you then need to define execChangedValue() methods on the client? — Samuel Renold
I don't understand your comment. What then would trigger check on server side if not execChangedValue()? If I want trigger validation on server when user change some data in field A, it need to be triggered from client, and execChangedValue seems to me like a right spot. — Marko Zadravec

Samuel Renold Samuel Renold · Accepted Answer · 2016-06-09T15:26:15

It is not possible to set the value of a field in the execChangedValue method of the same field. The framework detects a loop here.

What you could do instead is to use the method execValidateValue as follows

@Override
protected String execValidateValue(String rawValue) throws ProcessingException {
    MyFormData formData = new MyFormData();
    exportFormData(formData);
    formData = sendFormDataToServerAndDoValidation();
    importBCDE(formData);
    return formData.getTest().getValue();
  }

The method importBCDE would set fields B, C, D, and E, but not field A.

Eclipse Scout Neon on value set validation detect loop

1 Answers