SelectSingleNode (XmlDoc/XmlNode function): Difference between revisions
mNo edit summary |
mNo edit summary |
||
| Line 1: | Line 1: | ||
{{Template:XmlDoc/XmlNode:SelectSingleNode subtitle}} | {{Template:XmlDoc/XmlNode:SelectSingleNode subtitle}} | ||
==Syntax== | ==Syntax== | ||
| Line 17: | Line 16: | ||
==Usage notes== | ==Usage notes== | ||
<ul> | <ul> | ||
<li>If the result of the | <li>If the result of the <var class="term">xpath</var> argument XPath expression is empty, a <var>Null</var> is returned. | ||
</ul> | </ul> | ||
| Line 51: | Line 50: | ||
</p> | </p> | ||
<li>As a variation on the previous example, say the XML document is the same as in that example, except it contains additional third-level nodes <code>a4</code> through <code>a10</code>, and to each of them you want to add a <code>b</code> attribute whose values are, respectively, <code>b4</code> through <code>b10</code>. | <li>As a variation on the previous example, say the XML document is the same as in that example, except it contains additional third-level nodes <code>a4</code> through <code>a10</code>, and to each of them you want to add a <code>b</code> attribute whose values are, respectively, <code>b4</code> through <code>b10</code>. | ||
<p>Instead of a series of <var>SelectSingleNode</var> statements as in the example above, you might want to use a loop with <var>SelectSingleNode</var> and an | <p>Instead of a series of <var>SelectSingleNode</var> statements as in the example above, you might want to use a loop with <var>SelectSingleNode</var> and an XPath pattern like the following:</p> | ||
<p class="code">for %i from 2 to 10 | <p class="code">for %i from 2 to 10 | ||
%n1 = %doc:selectSingleNode('/*/F[' with %i with ']/*') | %n1 = %doc:selectSingleNode('/*/F[' with %i with ']/*') | ||
| Line 69: | Line 68: | ||
</ol> | </ol> | ||
==Request- | ==Request-cancellation errors== | ||
<ul> | <ul> | ||
<li><var class="term">xpath</var> is invalid. | <li>The <var class="term">xpath</var> expression is invalid. | ||
<li>Insufficient free space exists in CCATEMP. | <li>Insufficient free space exists in CCATEMP. | ||
</ul> | </ul> | ||
| Line 78: | Line 77: | ||
<ul> | <ul> | ||
<li>To select a list of nodes, use <var>[[SelectNodes (XmlDoc/XmlNode function)|SelectNodes]]</var>. | <li>To select a list of nodes, use <var>[[SelectNodes (XmlDoc/XmlNode function)|SelectNodes]]</var>. | ||
<li>For more information about using | <li>For more information about using XPath expressions, see [[XPath|"XPath"]]. | ||
</ul> | </ul> | ||
{{Template:XmlDoc/XmlNode:SelectSingleNode footer}} | {{Template:XmlDoc/XmlNode:SelectSingleNode footer}} | ||
Revision as of 15:49, 6 June 2011
Get selected node as XmlNode (XmlDoc and XmlNode classes)
Syntax
%nod = nr:SelectSingleNode[( [xpath])] Throws XPathError
Syntax terms
| %nod | An XmlNode, which will be set to point to the selected node. |
|---|---|
| nr | An XmlDoc or XmlNode, used as the context node for the xpath expression. If an XmlDoc, the Root node is the context node. |
| xpath | A Unicode string that is an Xpath expression that results in a nodelist. The first node (in document order) of the nodes found by the expression is returned by the method.
This is an optional argument whose default is a period (.) value: that is, the node referenced by the method object (nr). Prior to Sirius Mods Version 7.6, this argument is an EBCDIC string. |
Usage notes
- If the result of the xpath argument XPath expression is empty, a Null is returned.
Examples
- In the following example, SelectSingleNode selects individual nodes to which attributes are then added:
begin %doc is object xmlDoc %doc = new %n1 is object xmlNode %doc:loadXml('<top><F><a1/></F><F><a2/></F><F><a3/></F></top>') %n1 = %doc:selectSingleNode('/*/F') call %n1:AddAttribute('b', 'b1') %n1 = %doc:selectSingleNode('/*/F[2]/*') call %n1:addAttribute('b', 'b2') %n1 = %doc:aelectSingleNode('/*/F[3]/a3') Call %n1:addAttribute('b', 'b3') call %doc:print end
The example result follows:
<top> <F b="b1"> <a1/> </F> <F> <a2 b="b2"/> </F> <F> <a3 b="b3"/> </F> </top>
- As a variation on the previous example, say the XML document is the same as in that example, except it contains additional third-level nodes
a4througha10, and to each of them you want to add abattribute whose values are, respectively,b4throughb10.Instead of a series of SelectSingleNode statements as in the example above, you might want to use a loop with SelectSingleNode and an XPath pattern like the following:
for %i from 2 to 10 %n1 = %doc:selectSingleNode('/*/F[' with %i with ']/*') %n1:addAttribute('b', 'b' with %i with ) end For
Alternatively, you might want to gather the third-level nodes into an XmlNodelist (using SelectNodes), then loop through the nodes in that nodelist, as follows:
%nl1 is object xmlnodelist ... %nl1 = %doc:selectNodes('/*/F/*') for %i from 2 to %nl1:count Call %nl1:item(%i):AddAttribute('b', 'b' with %i with ) end for
This approach requires a less-creative XPath expression, and it has the advantage that XmlNodelists are always arranged in document order, whereas XPath selections in some cases (although not in this one) use the reverse of document order. For more information about this ordering issue, see “Order of nodes: node sets versus nodelists”.
Request-cancellation errors
- The xpath expression is invalid.
- Insufficient free space exists in CCATEMP.
See also
- To select a list of nodes, use SelectNodes.
- For more information about using XPath expressions, see "XPath".