How to select xml elements within a namespace? - asp.net

I'm trying to understand this xslt.
What does the below xslt command select exactly? what are "following-sibling", "aic" and "pstyle"?
"aic" seems to be a namespace.
What xml input the below xslt work with?
<xsl:stylesheet exclude-result-prefixes="aic"
version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:aic="http://ns.adobe.com/AdobeInCopy/2.0/" >
<xsl:template match="/">
<xsl:value-of select="following-sibling::aic:pstyle"/>
</xsl:template>
</xsl:stylesheet>

following-sibling::aic:pstyle
following-sibling is the axis, denoting which "direction" to look for nodes, in this case it looks at nodes which are after the current context node in document order but share the same parent as the current node. If you don't specify an axis the default is child, which looks for child nodes of the current context node.
aic:pstyle is a selector that looks for elements whose local name is pstyle and whose namespace URI is http://ns.adobe.com/AdobeInCopy/2.0/ (the one that is mapped to the prefix aic in the stylesheet).
The source XML need not use the same prefix, e.g. the expression would match an element that looks like
<pstyle xmlns="http://ns.adobe.com/AdobeInCopy/2.0/">
or
<foo:pstyle xmlns:foo="http://ns.adobe.com/AdobeInCopy/2.0/">
in the original XML.
As JLRishe points out, this particular XPath will not match anything if the current context is the document node /, for the expression to be meaningful it would have to be executed in a context where the current node is an element (or comment, processing instruction or text node) at least two levels down i.e. a child of the document element or deeper.
<example xmlns="http://ns.adobe.com/AdobeInCopy/2.0/">
<pstyle id="1"/>
<foo/>
<pstyle id="2"/>
<pstyle id="3"/>
</example>
If executed with the foo element as the context node, the expression would select pstyle elements 2 and 3, but not 1.

Related

Saxon HE 9.7 XQuery results and existing document

I am new to Saxon.
In my java application, I have a requirement that I need to XQuery an existing dom4j document. The XQuery is to order few elements in an descending order by serialNo:
<?xml version="1.0" encoding="UTF-8"?>
<dataOfBooks:DataOfBooks xmlns:dataOfBooks="DataOfBooks">
<Id>ID123</Id>
<books>
<book>
<name>ccc</name>
<serialNo>77</serialNo>
</book>
<book>
<name>aaa</name>
<serialNo>99</serialNo>
</book>
</books>
</dataOfBooks:DataOfBooks>
Once I get the XQuery results, I need to add those back to the above existing document. I tried using net.sf.saxon.s9api. I was able to get the XQuery results back as below:
<?xml version="1.0" encoding="UTF-8"?>
<result:sequence
xmlns:result="http://saxon.sf.net/xquery-results"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<result:element>
<book xmlns:data="dataOfBooks">
<name>aaa</name>
<serialNo>99</serialNo>
</book>
<book xmlns:data="dataOfBooks">
<name>aaa</name>
<serialNo>77</serialNo>
</book>
</result:element>
</result:sequence>
But I have two issues. 1) the result has namespaces and extra stuff that I do not want. 2) It is not very clear to me as which Saxon API to use to add the XQuery results to the existing document. So that the resultant document looks as:
<?xml version="1.0" encoding="UTF-8"?>
<dataOfBooks:DataOfBooks xmlns:dataOfBooks="DataOfBooks">
<Id>ID123</Id>
<books>
<book>
<name>aaa</name>
<serialNo>99</serialNo>
</book>
<book>
<name>ccc</name>
<serialNo>77</serialNo>
</book>
</books>
</dataOfBooks:DataOfBooks>
One more question - I tried using dynamicContext and treeinfo classes since I though the usage of treeinfo API might be more optimal, but no luck. If you think, usage of TreeInfo API is efficient, I really appreciate a code example for my requirement. Your help is much appreciated.
Thanks in advance for your time and interest.
The fact that your XQuery code is producing unwanted namespaces is because your query is wrong, but we can't tell you how it is wrong unless you show us the code.
The result:sequence in your output suggests that you have somehow contrived to ask for output in "wrapped" format, which suggests some kind of misuse of Saxon APIs. Again, without seeing your code, we can't tell you exactly what you have done wrong.
To make small changes to an existing document, leaving the rest unchanged, I would normally recommend XSLT over XQuery. In XSLT 3.0, you can sort the books by name using the following stylesheet:
<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
version="3.0">
<xsl:mode on-no-match="shallow-copy"/>
<xsl:template match="books">
<xsl:copy>
<xsl:perform-sort select="book">
<xsl:sort select="name"/>
</xsl:perform-sort>
</xsl:copy>
</xsl:template>
</xsl:transform>
In both XQuery and XSLT, the result of your query/transformation is a new document, which you can use in place of the original. If you want to make in-situ updates to an existing document, you can do this using XQuery Update; however Saxon does not support XQuery Update against documents in DOM4J format.
Saxon does allow you to capture the result of a query or transformation as a DOM4J Document, and you could use DOM4J APIs to graft this document (or rather, its outermost element) back into the original DOM4J document.
Later
You have now provided your code (you should have provided it as an edit to the original question, not as an answer).
I guess your DOMWriter is the DOM4J class of that name, which like much of DOM4J is rather badly documented. But I think it is copying the DOM4J tree to a DOM tree, which you definitely don't want to do. If you really want to copy the tree to make it convenient for Saxon, you should copy it to a Saxon tree, but for this use case it's best to leave it in DOM4J form. Use
DocumentBuilder builder = processor.newDocumentBuilder();
XdmNode inDoc = builder.wrap(dom4jdoc);
When you run your query, the resulting XdmValue will now be a sequence of XdmNode objects, each of which is a wrapper around a DOM4J Element node. These element nodes are still attached to the original DOM4J tree, and they still have their original namespaces. There is no need to serialize the result to lexical XML.
You can copy the result to a List value by writing
List<Element> sortedNodes = new ArrayList<Element>();
for (XdmItem item : result) {
sortedNodes.add(((Element)((XdmNode)item).getExternalNode()));
}
and then (if I read the DOM4J documentation correctly) you can replace the content of the containing books element with
Element books = (Element)sortedNodes.get(0).getParent();
List booksContent = books.elements();
booksContent.clear();
booksContent.addAll(sortedBooks);

Logical Existence doesn't work - BizTalk Mapper

This problem has confounded me for a while now. I have a flat file with segments and tag identifiers. One of the segments is optional. That is fine, but i need logic to determine if this segment exists. If it does not exist i need to do something else. All works as planned if the segment exists. If it doesn't, it appears BizTalk does not even recognize or execute any functoids related to the segment.
Here is the flat file segment:
And here is my Logical Existence connected to a Logical NOT:
Again, if the segment is completely gone (meaning no flat file xml nodes are created/translated), the Logical Existence does not even execute. I've tried scripts, functoids. I'm becoming convinced this is a bug in the mapper. Any help appreciated.
Try using the Value Mapping functoid instead of the Value Mapping (Flattening) functoid.
Also ensure that the parameters of the Value Mapping functoids are in the correct order. The logical operator must be the first parameter. Sometimes the parameters go out of order and the functoid stops working as expected.
Since your input file is a flat file, the FFDASM is creating an empty node. The test run by Logical Existence evaluates to true on an empty node. Logical String should work here (I was previously thinking it would return true for an empty string but it shouldn't).
However, in this case, I'd probably replace all of that (including the value mapper) with a C# scripting functoid:
public string AllowIfNotEmpty(string test, string output)
{
if (!string.IsNullOrWhiteSpace(test))
return output;
return "";
}
Give it the input of the node currently linked to Logical String first, and the second input to your Value Mapping(flattening) second, and output it directly to your destination node.
You could put that into a helper assembly if it's something you use in multiple places.
If you wanted to keep it as XSLT, you could do a custom call template:
<xsl:template name="OutputIfNotEmpty">
<xsl:param name="test" />
<xsl:param name="output" />
<xsl:if test="normalize-space($test) != ''">
<xsl:element name="OutputElementName">
<xsl:value-of select="$output" />
</xsl:element>
</xsl:if>
</xsl:template>

Access the HTTP Response from xdmp:http-get()

Using MarkLogic to pull in data from a web service with xdmp:http-get() or xdmp:http-post(), I'd like to be able to check the headers that come back before I attempt to process the data. In DQ I can do this:
let $result := xdmp:http-get($query,$options) (: $query and $options are fine, I promise. :)
return $result
And the result I get back looks like this:
<v:results v:warning="more than one node">
<response>
<code>200</code>
<message>OK</message>
<headers>
<server>(actual server data was here)</server>
<date>Thu, 07 Jun 2012 16:53:24 GMT</date>
<content-type>application/xml;charset=UTF-8</content-type>
<content-length>2296</content-length>
<connection>close</connection>
</headers>
</response>
followed by the actual response. the problem is that I can't seem to XPath into this response node. If I change my return statement to return $result/response/code I get the empty sequence. If I could check that code to make sure I got a 200 back before attempting to process the actual data that came back it would be much better than using try-catch blocks to see if the data exists and is sane.
So, if anyone knows how to access those response codes I would love to see your solution.
For the record, I have tried xdmp:get-response-code(), but it doesn't take any parameters, so I don't don't know what response code it's looking at.
You're getting burned by two gotchas at once:
awareness of namespaces
awareness of document nodes
First, the namespace. The XML output of the http-get function is in a namespace as seen by the top-level element:
<response xmlns="xdmp:http-get">
To successfully access elements in that namespace, you need to declare a prefix in your query bound to the correct namespace, and then use that prefix in your XPath expressions. For example:
declare namespace h="xdmp:http-get";
//h:code
Now lets talk about document nodes. :-)
You're trying to access $result as if it is a document node containing an element, but in actuality, it is a sequence of two root nodes (so they're not siblings either). The first one (the one you're interested in here) is a parentless <response> element—not a document containing a <response> element.
This is a common gotcha: knowing when a document node is present or not. Document nodes are always invisible when serialized (hence the gotcha), and they're always present on documents stored in the database. However, when you just use a bare element constructor in XQuery (as the http-get implementation does), you construct not a document node but an element node without a document node parent.
For example, the following query will return the empty sequence, because it's trying to get the <foo> child of <foo>:
declare variable $foo := <foo>bar</foo>;
$foo/foo
On the other hand, the following does return <foo>, because it's getting the <foo> child of the document node (which has to be explicitly constructed, in XQuery):
$declare variable $doc := document{ <foo>bar</foo> };
$doc/foo
So you have to know how a given function's API is designed (whether it returns a document containing an element or just an element).
To solve your problem, don't try to access $result/h:response/h:code (which is trying to get the <response> child of <response>). Instead, access $result/h:code (or more precisely $result[1]/h:code, since <response> is the first of a sequence of two nodes returned by the http-get function).
For more information on document nodes, check out this blog article series: http://community.marklogic.com/blog/document-formats-part1

Reference to undeclared namespace prefix when parsing MSXML

How do I solve the
Reference to undeclared namespace prefix: '%s'
problem with Microsoft's msxml implementation?
I'm using an XML feed from a government web-site that contains values i need to parse. The xml contains namespaces:
<?xml version="1.0" encoding="ISO-8859-1"?>
<rdf:RDF
xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
xmlns="http://purl.org/rss/1.0/"
xmlns:cb="http://www.cbwiki.net/wiki/index.php/Specification_1.1"
xmlns:dc="http://purl.org/dc/elements/1.1/"
xmlns:dcterms="http://purl.org/dc/terms/"
xmlns:xsi="http://www.w3c.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.w3c.org/1999/02/22-rdf-syntax-ns#rdf.xsd">
<item rdf:about="http://www.bankofcanada.ca/stats/rates_rss/STATIC_IEXE0101.xml">
<cb:statistics>
<cb:exchangeRate>
<cb:value decimals="4">1.0351</cb:value>
<cb:baseCurrency>CAD</cb:baseCurrency>
<cb:targetCurrency>USD</cb:targetCurrency>
<cb:rateType>Bank of Canada noon rate</cb:rateType>
<cb:observationPeriod frequency="daily">2011-05-09T12:15:00-04:00</cb:observationPeriod>
</cb:exchangeRate>
</cb:statistics>
</item>
</rdf:RDF>
Running the XPath query:
/rdf:RDF/item/cb:statistics/cb:exchangeRate/cb:targetCurrency
fails with the error:
Reference to undeclared namespace prefix: 'rdf'
Edit:
If i edit the original XML to remove all use of namespaces:
<?xml version="1.0" encoding="ISO-8859-1"?>
<rdf>
<item>
<statistics>
<exchangeRate>
<value decimals="4">1.0351</value>
<baseCurrency>CAD</baseCurrency>
<targetCurrency>USD</targetCurrency>
<rateType>Bank of Canada noon rate</rateType>
<observationPeriod frequency="daily">2011-05-09T12:15:00-04:00</observationPeriod>
</exchangeRate>
</statistics>
</item>
</rdf>
The query /rdf/item/statistics/exchangeRate/baseCurrency doesn't fail, and returns nodes:
<baseCurrency>CAD</baseCurrency>
How do i get Microsoft XML to work with namespaces?
Edit 2
i've tried adding SelectionNamespaces to the DOMDocument object:
doc.setProperty('SelectionNamespaces', 'xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:cb="http://www.cbwiki.net/wiki/index.php/Specification_1.1"');
Now the xpath query doesn't fail, but it also returns no nodes:
nodes = doc.selectNodes('/rdf:RDF/item/cb:statistics/cb:exchangeRate/cb:targetCurrency');
See also
“undeclared reference to namespace prefix ” error
XMLReader - How to handle undeclared namespace
PRB: Specifying Fully Qualified Element Names in XPath Queries
XPath not working properly.
Using SelectionNamespaces is the correct approach, you are just missing a namespace.
Notice that your XML document explicitly sets the default namespace as follows:
xmlns="http://purl.org/rss/1.0/"
This means that any element without a prefix, such as the item element, is actually in the default namespace. So if you want to select that element with an XPath expression, you must first set an appropriate selection namespace.
To do this, you can change your call to setProperty like so:
doc.setProperty('SelectionNamespaces', 'xmlns:rss="http://purl.org/rss/1.0/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:cb="http://www.cbwiki.net/wiki/index.php/Specification_1.1"');
Here you've assigned the default namespace from the document to the rss: prefix in your XPath expression. With that change in place, the following XPath expression should work correctly:
nodes = doc.selectNodes('/rdf:RDF/rss:item/cb:statistics/cb:exchangeRate/cb:targetCurrency');
It works because it references the item element using the correct namespace. The fact that the prefix differs between the XPath expression and the original document is immaterial. It is the namespace which the prefix is bound to that matters.
doc.setProperty('SelectionNamespaces', 'xmlns:rss="http://purl.org/rss/1.0/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#" xmlns:cb="http://www.cbwiki.net/wiki/index.php/Specification_1.1"');
Dont forget to load the xsd file or schema to the xmldoc object
is the way to go
I dont have enough reputation to comment. But that bit there saved me a lot of time.
Thank you so much
If you are using XMLSerializer and see this error, it is likely that you are running into the IE bug described here:
https://stackoverflow.com/a/11399681
It took me a lot of time to realize that this was happening, so I thought it best to link these two issues.

issue with a xmlns

I have an xml file and an xslt file.
The xml file has a xmlns="exa:com.test" attribute.
If i remove this attribute in the xml the xpath sentences in my xslt works. But if i leave it, doesnt work.
Im using the following code to mix xml and xslt:
XslCompiledTransform transformer = new XslCompiledTransform();
transformer.Load(HttpContext.Current.Server.MapPath("xslt\\searchresults.xslt"));
transformer.Transform(xmlreader, null, utf8stringwriter);
What im doing wrong? How could i mix xml and xslt if the xml has the xmlns attribute on top?
The xmlns attribute without prefix name replaces the default namespace, so that your query matches nodes with a different (empty) namespace. You need to use a prefixed namespace in the XSLT XPath queries (or a XmlNamespaceManager for isolated XPath queries) and your queries will work again as expected.
In the XSLT:
<xsl:stylesheet ... xmlns:exa="exa:com.test">
Then, assuming that you used to match for instance xyz, you now change your query like this:
<xsl:template match="exa:xyz"> ...
In general you might want to read some docs on XML namespaces.
It should be noted though, though the namespace string is to just be seen as an exact literal string that is used as an identifier with no other meaning. The string must conform to an IANA uri, this is to guarantee uniqueness of namespaces. Some parsers refuse to parse namespaces that do not conform.
Also note that because they are strings http://www.w3.org/1999/xhtml and for instance http://w3.org/1999/xhtml/ are for the purposes of namespaces completely different namespaces.
You might want to read up on how namespaces in XML work. exa:com.test is as far as I know not a valid namespace string.

Resources