• Chapter 1: Getting Started with Stylus Studio
• Chapter 2: Editing and Querying XML
• Chapter 3: Converting Non-XML Files to XML
• Chapter 4: Working with XSLT
• Chapter 5: Creating XSLT Using the XSLT Mapper
• Chapter 6: Debugging Stylesheets
• Chapter 7: Defining XML Schemas
• Chapter 8: Defining Document Type Definitions
• Chapter 9: Writing XPath Expressions
  • About the XPath Processor
  • Sample Data for Examples and Testing
  • Getting Started with Queries
  • Specifying the Nodes to Evaluate
  • Handling Strings and Text
  • Specifying Boolean Expressions and Functions
  • Specifying Number Operations and Functions
  • Comparing Values
  • Finding a Particular Node
  • Obtaining a Union
  • Obtaining Information About a Node or a Node Set
    • Obtaining the Name of a Node
    • Obtaining Namespace Information
    • Obtaining the URI for an Unparsed Entity
    • Determining the Number of Nodes in a Collection
    • Determining the Context Size
  • Using XPath Expressions in Stylesheets
  • Accessing Other Documents During Query Execution
  • XPath Quick Reference
• Chapter 10: Working with XQuery in Stylus Studio
• Chapter 11: Composing Web Service Calls
• Chapter 12: Accessing Relational Data as XML
• Chapter 13: Extending Stylus Studio
• Chapter 14: Stylus Studio GUI Reference

Home > Online Product Documentation > Table of Contents > Obtaining Information About a Node or a Node Set

Obtaining Information About a Node or a Node Set

In a query, you can perform the following operations to obtain information about a node:

Obtaining the Name of a Node

The name() function returns a string that contains the tag name of the node, including the namespace prefix, if any.

The following query returns the name of the third element in bookstore, which is "magazine".

name(/bookstore/*[3])
               

            

Wildcards

An asterisk ( * ) specifies a wildcard name for element names. If there are comments before the third element in the preceding example, this query does not include them in the count. See Filtering Results of Queries.

Obtaining Namespace Information

You can call functions to obtain namespace information. This topic discusses

In addition to a discussion of the functions you call, this section covers the following:

Obtaining the Namespace URI

To obtain the URI for a namespace, call the namespace-uri() function. The format is

string namespace-uri(node-set?) 
               

            

The namespace-uri() function returns the namespace URI of the expanded name of the node in the node-set argument that is first in document order. If the node-set argument is empty, the first node has no expanded name, or the namespace URI of the expanded name is null, the XPath processor returns an empty string. If you omit the argument, it defaults to a node set with the context node as its only member.

Call the namespace-uri() function on element or attribute nodes. For example, the query

/bookstore/my:book/namespace-uri()
               

            

returns the string

              "http://www.placeholder-name-here.com/schema/"
               

            

For any other type of node, the XPath processor always returns an empty string.

Obtaining the Local Name

To obtain the local portion of a node name, excluding the prefix, call the local-name() function. The format is

string local-name(node-set?) 
               

            

The local-name() function returns the local part of the expanded name of the node in the node-set argument that is first in document order. If the node-set argument is empty or the first node has no expanded name, the function returns an empty string. If you omit the argument, it defaults to a node set with the context node as its only member. For example, the following query returns my:book nodes:

/bookstore/my:*[local-name()="book"]
               

            

Obtaining the Expanded Name

To obtain the expanded name of a node, call the name() function. The expanded name is the namespace prefix, if any, plus the local name. The format is

string name(node-set?) 
               

            

The name() function returns a string that represents the expanded name of the node in the node-set argument that is first in document order. The returned string represents the expanded name with respect to the namespace declarations in effect on the node whose expanded name is being represented.

Typically, this is the name in the XML source. This need not be the case if there are namespace declarations in effect on the node that associate multiple prefixes with the same namespace.

If the node-set argument is empty or the first node has no expanded name, the XPath processor returns an empty string. If you omit the argument, it defaults to a node set with the context node as its only member.

Except for element and attribute nodes, the string that the name() function returns is the same as the string the local-name() function returns.

Specifying Wildcards with Namespaces

Element and attribute names that include colons ( :) can include wildcards; that is, asterisks ( *). For example, queries can include *:*, *:a, or a:*.

Examples of Namespaces in Queries

The following example finds all book elements in the current context. This query does not return any book elements that are not in the default namespace. For example, it does not return my:book elements.

book 
               

            

The next query finds all book elements with the prefix my. This query does not return unqualified book elements; that is, book elements in the default namespace.

my:book 
               

            

The following query finds all book elements with a my prefix that have an author subelement:

my:book[author] 
               

            

The following query finds all book elements with a my prefix that have an author subelement with a my prefix:

my:book[my:author] 
               

            

The next example returns the style attribute with a my prefix for book elements in the current context:

book/@my:style 
               

            

Obtaining the URI for an Unparsed Entity

To obtain the URI for an unparsed entity, call the unparsed-entity-uri() function. The format is

string unparsed-entity-uri(string) 
               

            

This function returns the URI of the unparsed entity with the specified name that is in the same document as the context node. If there is no such entity, this function returns an empty string.

Determining the Number of Nodes in a Collection

To obtain the number of nodes in a node set, call the count() function. The format is

number count(node-set) 
               

            

The count() function returns the number of nodes in the specified set. For example, the following query finds all authors who have more than ten publications:

//author[count(publications) > 10] 
               

            

To obtain the number of nodes in the current context, call the last() function, described in the next section.

Determining the Context Size

To obtain the number of nodes in the current context, call the last() function. The format is

number last() 
               

            

The last() function returns a number equal to the context size of the expression evaluation context. Essentially, the last() function returns the position number of the last node in document order for the current context. For example, the following query returns all books if there are three or more of them. There are three book elements in the current context. Consequently, this query returns three book elements.

/bookstore/book[last() >= 3]