Creating a mortgage calculator in Flash MX - Page 10

Validation

Everything will work fine providing the user enters sensible information in the text fields. Try clicking the Calculate button without entering data and you'll get a strange result. It's a good idea to add validation to form fields before the calculation is carried out so we can avoid this kind of result.

We'll use a dynamic text field to display any errors in the data entered. Add a dynamic text field to the right of the user input fields and give the variable the name ValidationMessage.

Change the CalculateRepayment function to the one shown below. The function tests each of the values and creates an error message if the test is not passed. The repayment amount on the second frame is only displayed if all tests are passed.

function CalculateRepayment(component) {

   //do validation

   if (intPrincipal <= 0 || intPrincipal == undefined) {

       ValidationMessage = "Principal must be a number greater than 0";

   }

   else if (floInterest > 100 || floInterest < 1 || floInterest == undefined) {

       ValidationMessage = "Annual interest must be between 1 and 100 %";

   }

   else if (intTerm <=0 || intTerm == undefined) {

      ValidationMessage = "Loan term must be greater than 0";

   }

   else if (intRepayments == undefined || intRepayments <=0) {

      ValidationMessage = "Please select a repayment period";

   }

   else {

      //display calculation

      gotoAndPlay("calculate");

   }

}

You'll also need to add the following line to the first frame of the actions layer. This will clear the validation message text.

ValidationMessage="";