Behavior: Calculate

Overview

The Calculate behavior is sugar for calculating a form element based on the values of other form elements. For example, Project.Timesheet.Edit.xslt includes UnitCount, Rate and AmountMoney fields, where AmountMoney = UnitCount * Rate.

<form>

  <input type="text" id="UnitCount"/>

  <input type="text" id="Rate"/>

  <input type="text" id="AmountMoney" data-behavior="Calculate" data-calculate-options="{{'depends': 'UnitCount,Rate', 'calculate': 'multiply'}}" />

</form>

This is simply more concise than:

<form>

  <input type="text" id="UnitCount" onchange="calculateAmount();"/>

  <input type="text" id="Rate" onchange="calculateAmount();"/>

  <input type="text" id="AmountMoney" />

  <script type="text/javascript">

function calculateAmount()

{

  document.id('AmountMoney').value = "";

  if (!isNaN(document.id('UnitCount').value) && !isNaN(document.id('Rate').value)) {

    document.id('AmountMoney').value = parseFloat(document.id('UnitCount').value) * parseFloat(document.id('UnitCount').value);

  }

}

  </script>

</form>

Behavior Options

Options for the Calculate behavior comprise:

• • depends (String, required): comma-separated list of element id's to consider in the calculation

  • defaultValue (String, defaults to ''): default value to set if there are not enough values to perform the calculation

  • calculate (String, defaults to 'sum'): name of the calculation function defined in the qbo3.Calculator object

The qbo3.Calculator object is used to define calculation functions; by default it contains 'sum' and 'multiply'.  If you need more complex calculation logic, you can implement as follows:

qbo3.Calculator = Object.merge(qbo3.Calculator || {}, {

myCalc: function (element, depends, options) { ... }

});

and then reference it with:

<input type="text" id="AmountMoney" data-behavior="Calculate" data-calculate-options="{{'depends': 'UnitCount,Rate', 'calculate': 'myCalc'}}" />

See qbo.ApplicationWeb > Scripts > qbo.Math.js for the behavior, including the definition of sum and multiply in the qbo3.Calculator object.