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Wendell Piez edited this page Mar 30, 2023 · 34 revisions

This page is a collection of assorted tasks and topics developers from the NIST OSCAL Team will need or want as part of development activities. Documentation items, when specifically relevant to OSCAL, could and should make their way into official documentation with commits to the git repository's Markdown files. For official documentation, bug reports for error corrections and feature request issues identify and track work items. Changes to information here are not tracked that way. See the note on the bottom of this page. Information this page and children pages are for supporting activities underlying OSCAL development: code snippets for testing data format snippets (JSON, XML, YAML), software configuration, and common queries in different querying languages (JMESPath for JSON, XPath for XML, etc.).

Software

OxygenXML

Code

XPath

How do I check for multiple kinds of elements at the same time with XPath 3.0?

Let's say we want to look for the following OSCAL syntax elements in XML at the same time:

  • any definition of a field with the name "with-id" in one or more target documents
  • any definition of a flag with the name "pattern" in one or more target documents
  • any definition of an assembly with the name "matching" in one or more target documents

Apply the following query against the target document(s) (for this example any Metaschema definition in src/metaschema/*.xml), observing use of the | ("union") operator:

//(
    define-flag[@name='pattern']
   | define-assembly[@name='matching']
   | define-field[@name='with-id']
 )

Here is a sneakier way to do something similar:

//@name[.=('pattern','matching','with-id')]/parent::*

parent::* can also be shortened to .. for those who prefer.

Mathematically, this path returns a superset of the nodes returned by the first path given, although in a particular metaschema they are likely to be the same.

This takes advantage of a feature of general comparison operators in XPath (=, <, >, <=, >=) namely that they support comparing sequences, i.e. many values on either side of the operand, hence .=('a','b','c').

NOTE: This information exists for the benefit of NIST staff. Although the community may reference or inquire about content, this material is not explicitly intended for community support. The community may create issues to report bugs or request enhancements related to this documentation, but there is no support guarantees for this material. All issues will be considered on a case by case basis.

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