Defining an XPath conditional expression for a transform

The following examples show how to define simple XPath conditional expression for a transform when you have non-repeating elements:

Example: XPath expression to check a Boolean input element

This example shows how to define the XPath expression for a Boolean element so that it evaluates to true. The expression depends on the value of the Boolean element.

The XML schema for the element is the following:

<element name="IsEmployee" type="boolean"></element>

When the value of a Boolean element is set to false, the XPath expression that you define is the following:

fn:not($IsEmployee)

When the value of the Boolean element is set to true, the XPath expression that you define is the following:

$IsEmployee=fn:true()

The $IsEmployee expression on its own tests if the element exists and always evaluates to true if the element exists regardless of what value it is set to.

Example: XPath expression to check if the value of a numerical input element is greater than a constant value

This example shows how to define an XPath expression that evaluates to true when the value of a numerical element is greater than 200.

The XML schema for the element is the following:

<element name="BusinessUnit" type="int" ></element>

The XPath expression that you define is the following:

$BusinessUnit > 200

Example: XPath expression to check if a numerical input element has a specific value

This example shows how to define an XPath expression that evaluates to true when the numerical input element has a value of 0.

The XML schema for the element is the following:

<element name="QtyBooks" type="int" ></element>

The XPath expression that you define is the following:

$QtyBooks = 0

Example: XPath expression to check the string length of an input element

This example shows how to define an XPath expression that evaluates to true when the length of a string is 10.

The XML schema for the elements are the following:

<element name="Name" type="string" ></element>

<element name="BusinessUnit" type="string" ></element>

The XPath expression that you define is the following:

fn:string-length($BusinessUnit) = 10

Example: XPath expression to check if a string input element is set to the empty string

This example shows how to define an XPath expression that evaluates to true when a string element is empty.

To define an XPath expression that checks if a string element is empty, you must use the operator !=.

The XML schema for the element is the following:

<element name="Name" type="string" ></element>

The XPath expression that you define is the following:

$Name != ''

Example: XPath expression to check if a repeating element is empty

This example shows how to define an XPath expression that evaluates to true when a repeating element, which is referred to as a sequence, is empty.

The effective Boolean value of an empty sequence is false. You could use fn:not($Address), but it is easier to understand if you use fn:empty().

The XPath function fn:empty() evaluates to true if a sequence is empty.

The XML schema for the element is the following:

<xsd:element form="qualified" name="Address" type="mqsistr:Address" maxOccurs="unbounded" minOccurs="0" />

The XPath expression that you define is the following:

fn:empty($Address)

Example: XPath expression to check if an optional input element is present

This example shows how to define an XPath expression that evaluates to true when an optional element is present.

Use the fn:exists XPath function if the input element is a boolean. Otherwise, you can use the effective Boolean value.

The XML schema for the element is the following:

<element name="BookName" type="string" maxOccurs="unbounded" minOccurs="0" ></element>

The XPath expression that you define is the following:

$BookName

Example: XPath expression to check if a complex input element has no content, that is, it is empty

To determine whether a complex element is empty, you must check for the presence of child elements or attributes.

Testing the effective Boolean value of elements or attributes that are present in a complex type will yield true. You can use the fn:not XPath function to invert a boolean.

The fn:not function accepts a sequence of items. The value that this function returns is true if any of the arguments is either a single Boolean value false, a zero-length string, the number 0 or NaN, or the empty sequence. Otherwise, it returns false.

This example shows how to define an XPath expression that evaluates to true when the complex input element has no children.

The XML schema for the elements are the following:

<complexType name="Address">
    <sequence> 
	<element name="Type" type="string"/> 
	<element name="Number" type="integer"/>
	<element name="Street" type="string"/> 
	<element name="Postcode" type="string"/> 
	<element name="City" type="string" /> 
	<element name="Country" type="string"/> 
	<element name="AdditionalInfo" type="string"/> 
    </sequence> 
</complexType>

The XPath expression that you define to check for child elements being present in a complex element is the following:

fn:not($Address/* )

The XPath expression that you define to check for attributes being present in a complex element is the following:

fn:not($Address/@* )

The XPath expression that you define to check for elements and attributes being present in a complex element is the following:

fn:not($Address/*) and fn:not($Address/@* )