Checking whether the value of an input element is empty
Use appropriate expressions to test for empty input values, depending on whether the element is a simple or complex type.
About this task
You can define conditional expressions in a transform to determine whether the transform is applied or not in your message map. For example, you might decide not to apply a transform if the input value is empty.
For simple string types, you can test whether
the element is empty by comparing with the empty string '' (two
single quotation marks). For example, to check whether a string element
that is represented by the variable name str is empty,
use the following expression:
$str = ''If the element is also nillable, use the following expression:
(fn:nilled( $elementName) = false) and $str = ''Other
simple types have no natural empty value. For example, with numerical
type elements the value must always contain a minimum set of valid
digits. In this case, you might consider a particular value to be
empty, and so test for that value. To check whether a number element
that is represented by the variable name num has
a zero value, use the following expression:
$num = 0To
determine whether a complex element is empty, check for child elements
or attributes. For example, to check a complex element that is represented
by the variable name comp, use the following expression:
fn:not( $comp/* or $comp/@* )If the complex element allows mixed content, check for text content as well.
fn:not( $comp/text() or $nodes/* or $nodes/@* )Procedure
Take the following steps to define a conditional expression on a Move transform between a source and target string element. The expression ensures that the transform is not applied if the input data is an empty string.