Tips

XPath tips

XForms requested type vs. XPath typed value

When type annotations are enabled and an XPath expression requires access to a typed value, if the value is not of the specified type, the expression stops its evaluation. This behavior is different from 3.9, where an untyped value would be returned instead.

Boolean comparisons

Consider:

<xf:bind ref="is-soap" type="xs:boolean"/>
...
<xf:action if="is-soap = 'true'">

This will cause an XPath dynamic error, because 'true' is a string and XPath will atomize (get an atomic value) the content of the is-soap node, which results in a boolean. Because there is no automatic conversion between the two, and error is raised and the action won't run. Instead, write:

<xf:action if="is-soap = true()">

Or:

<xf:action if="data(is-soap)">

Or:

<xf:action if="string(is-soap) = 'true'">

This latter expression works whether type annotations are enabled or not.

See also

• Form Builder forumlas examples