AS3 Flash How to make text fields required? - actionscript-3

Question

I want to know how to put restrictions in the fields like if the user didn't type anything or still has a blank field, then it should not submit but shows *required field or something like that. Examples would be great.
The codes. I don't know where to start from here
var fllname:TextField;
var address:TextField;
var ContactNo:TextField;
var quantity:TextField;
var otrack:TextField;
btnSubmit1.addEventListener(MouseEvent.CLICK, submit);
function submit(e:MouseEvent):void{
var urlvars: URLVariables = new URLVariables;
urlvars.fllname = fllname.text;
urlvars.Oadd = address.text;
urlvars.ContactNo = ContactNo.text;
urlvars.oquantiy = quantity.text;
urlvars.otrack = otrack.text;
urlvars.cake = txtCake.text;
urlvars.frosting = txtFrosting.text;
urlvars.topping = txtToppings.text;
urlvars.topping2 = txtToppings2.text;
urlvars.filling = txtFilling.text;
urlvars.amt = lblAmount.text;
var urlreq:URLRequest = new URLRequest("http://localhost/MCC/order.php");
urlreq.method = URLRequestMethod.POST;
urlreq.data = urlvars;
var loader : URLLoader = new URLLoader;
loader.dataFormat = URLLoaderDataFormat.VARIABLES;
loader.load(urlreq);
nextFrame();
}

Answer 1

You can use the enabled parameter to control if your btnSubmit1 is clickable, so you will probably need to start with is disabled.
btnSubmit1.enabled = false;
btnSubmit1.addEventListener(MouseEvent.CLICK, submit);
Next you will need to listen to the TextEvent.TEXT_INPUT event on all your TextFields
fllname.addEventListener(TextEvent.TEXT_INPUT,paramChanged);
address.addEventListener(TextEvent.TEXT_INPUT,paramChanged);
//etc etc
This will notify you any-time the user changes their value, you can then create a single function (or a function for each control) to test the values, once they pass you can re-enable the submit button.
function paramChanged(event:TextEvent):void
{
if (fllname.text != "" && address.text != "")//add your other fields here
{
btnSubmit1.enabled = true;
}
else
{
btnSubmit1.enabled = false;//If something changes that means we now fail the test you will want to disable the button again
}
}
You could make custom test functions for each field as needed.