I am new to using XPath and I am trying to retrieve a node via its attribute but the problem is that the attribute is case insensitive meaning I won't exactly know how the string is cased in the document.
So for example:
Given the document:
<Document xmlns:my="http://www.MyDomain.com/MySchemaInstance">
<Machines>
<Machine FQDN="machine1.mydomain.com">
<...>
</Machine>
<Machine FQDN="Machine2.MyDomain.Com">
<...>
</Machine>
</Machines>
</Document>
If I want to retrieve the machine1 I would use the XPath:
//my:Machines/my:Machine/*[#FQDN='machine1.mydomain.com']
But a similar XPath to get machine2 would fail becuase the case does not match:
//my:Machines/my:Machine/*[#FQDN='machine2.mydomain.com'] //Fails
I have seen various posts mention using something like (I am not sure how to apply Namespaces to this):
translate(#FQDN, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz')
But even if I got it to work it would be really cumbersome considering the number of times I would be using it.
Finally I have read that XPath 2.0 supports matches() and lower-case() but being new to XPath I don't understand how to apply them:
For example if I try the following I get an "Invalid Qualified name":
//my:Machines/my:Machine/[matches(#FQDN, '(?i)machine1.mydomain.com')]
//my:Machines/my:Machine/[lower-case(#FQDN, 'machine1.mydomain.com')]
Can someone provide a sample XPath that includes handling of Namespaces that would work?
Thanks
Your example XML and XPath statements don't match.
The sample XML elements are not bound to a namespace. The "my" namespace-prefix is declared, but not used for those elements, so they are in the "no namespace".
Your sample XPath is using predicate filters on the children of Machine rather than on the Machine element that has the #FQDN.
You could use either of these methods to look for the value case-insensitive:
matches() function, with a flag for case-insensitive matching:
//Machines/Machine[matches(#FQDN,'machine2.mydomain.com','i')]
upper-case() function to evaluate the upper-case strings:
//Machines/Machine[upper-case(#FQDN)=upper-case('machine2.mydomain.com')]
lower-case() function to evaluate the lower-case strings:
//Machines/Machine[lower-case(#FQDN)=lower-case('machine2.mydomain.com')]
Can someone provide a sample XPath that includes handling of
Namespaces that would work?
Not sure what you meant by the handling of namespaces, but if you wanted to match on those elements regardless of their namespace then you can use the wildcard operator for the namespace:
//*:Machines/*:Machine[matches(#FQDN,'machine2.mydomain.com','i')]
Related
I'm parsing an XML file with Nokogiri.
Currently, I'm using the following to get the value I need (the document includes multiple Phase nodes):
xml.xpath("//Phase[#text=' = STER P=P(T) ']")
But now, the uploaded XML file can have a text attribute with a different value. Thus, I'm trying to update my code using a regular expression since the value always contains STER.
After looking at a few questions on SO, I tried
xml.xpath("//Phase[#text~=/STER/]")
However, when I run it, I get
ERROR: Invalid predicate: //Phase[#text~=/STER/] (Nokogiri::XML::XPath::SyntaxError)
What am I missing here?
Alternatively, is there an XPATH function similar to starts-with` that looks for the substring within the entire value and not just at the beginning of it?
There are two problems with your code: first off, there is no =~ operator in XPath. The way to test whether text matches a regex is using the matches function:
//Phase[matches(#text, 'STER')]
Secondly, regex matching is a feature of XPath 2.0, but Nokogiri implements XPath 1.0.
Luckily, you are not actually using any regex features, you are simply checking for a fixed string, which can be done with XPath 1.0 using the contains function:
//Phase[contains(#text, 'STER')]
I am working on xquery requirement to identify the xml tag name() from the XML document using the regex. Later , will do the transformation on data.It searches the entire document and If i found match, am doing string :replace using xquery/xpath.
Please find some sample code which am looking for.
let $full-doc := fn:doc($uri)
if(fn:matches($full-doc,"<Hyperlink\b[^\>]*?>([A-Z][a-z]{2} [0-3]?[0-9]
[12][890][0-9]{2})</Hyperlink>"))
then $full-doc
else "regex is not working"
I am getting the following Error.
regex-match :
[1.0-ml] XDMP-REGEX: (err:FORX0002) fn:matches(fn:doc("44215.xml"), "
<Hyperlink\b[^\>]*?>([A-Z][a-z]{2} [0-3]?[0-9] [12][890][0-9]{2}...") -
- Invalid regular expression
Could some one please explain why my regex is not working ?
Looking at your requirement:
I am working on xquery requirement to identify the xml tag name() from the XML document using the regex.
You are going about this entirely the wrong way. XQuery doesn't see the lexical XML, it sees a tree of nodes. To find the name of an element, use an XPath expression to find the element, then use the name() function to get its name.
If you want to find an element whose name matches a regex, use //*[matches(name(), $regex)]
The word boundary code \b is not supported in XQuery (see https://www.w3.org/TR/xpath-functions-31/#regex-syntax).
But I guess you are looking for Hyperlink elements, not for a <Hyperlink> substring, so you should use a path expression:
let $doc := fn:doc($uri)
where $doc//Hyperlink[matches(., '([A-Z][a-z]{2} [0-3]?[0-9] [12][890][0-9]{2})')]
return $doc
I'm currently trying to extract the blurb, or summary from any given Wikipedia page, using XPath. Now, there are many places online where this has already been done: http://jimblackler.net/blog/?p=13, How to use XPath or xgrep to find information in Wikipedia?.
But, when I try to use similar XPath expressions, on a variety of pages, the returned results are strange. For the sake of this question, let's assume I'm trying to retrieve the very first paragraph in the printable Wikipedia page on Boston: http://en.wikipedia.org/w/index.php?title=Boston&printable=yes.
When I try to use this expression /html/body/div[#id='content']/div[#id='bodyContent']//p, only the last four words of the paragraph, "in the United States.", are returned.
Actually, the expression used above could be simplified to //div/p, but the results are the same.
Strangely, the links I linked to previously seem to use similar methods and return great results; originally, I imagined this was due to Wikipedia changing the formatting of their pages in recent years, but honestly, I can't seem to find what's wrong with both the expressions.
Does anyone have any idea about this?
When I try to use this expression
/html/body/div[#id='content']/div[#id='bodyContent']//p, only the
last four words of the paragraph, "in the United States.", are
returned.
There are a few problems here:
The XML document is in a default namespace. Writing XPath expressions to select nodes in a document that is in a default namespace is the most FAQ about XPath -- search for "XPath and default namespace". In short, any unprefixed name will most probably cause nothing to be selected. One must register the default namespace and associate a specific prefix with this namespace. Then any element name in the XPath expression must be written with this prefix. So, the expression above will become:
:
/x:html/x:body/x:div[#id='content']/x:div[#id='bodyContent']//x:p
where the "x:" prefix is associated to the "http://www.w3.org/1999/xhtml" namespace.
.2. Even the above expression doesn't select (only) the wanted node. In order to select only the first x:p from the above, the XPath expression must be specified as (note the brackets):
(/x:html/x:body/x:div[#id='content']/x:div[#id='bodyContent']//x:p)[1]
.3. As you want the text of the paragraph, an easy way to do this is to use the standard XPath function string():
string((/x:html/x:body/x:div[#id='content']/x:div[#id='bodyContent']//x:p)[1])
When this XPath expression is evaluated, I get the text of the paragraph -- for example in the XPath Visualizer I wrote some years ago:
I want to write xpath to check node contain '#'
<node1>
<node11>Some text</node11>
<node11>#2o11 PickMe</node12>
</node1>
I want to write xpath like "//node11[contains(,'#\d+')]". Whats correct way to check #
The correct XPath expression is:
//node11[contains(., '#')]
In your XML, the closing tag of the second subnote should be </node11> instead of </node12>.
If you are using xpath 2.0 you should be able to use something like:
"//node11[matches(.,'#\d+')]"
However, if you aren't using 2.0 you won't have regex support directly. If you are using 1.0 then you won't be able to match using \d+. But this will work:
"//node11[contains(.,'#')]"
Or even:
"//node11[starts-with(.,'#')]"
Use:
/*/node11[contains(., '#')]
Note: It is recommended to avoid using the // pseudo-operator because this most often leads to very slow evaluation of the XPath expression.
I'm trying to parse a webpage to get posts from a forum.
The start of each message starts with the following format
<div id="post_message_somenumber">
and I only want to get the first one
I tried xpath='//div[starts-with(#id, '"post_message_')]' in yql without success
I'm still learning this, anyone have suggestions
I think I have a solution that does not require dealing with namespaces.
Here is one that selects all matching div's:
//div[#id[starts-with(.,"post_message")]]
But you said you wanted just the "first one" (I assume you mean the first "hit" in the whole page?). Here is a slight modification that selects just the first matching result:
(//div[#id[starts-with(.,"post_message")]])[1]
These use the dot to represent the id's value within the starts-with() function. You may have to escape special characters in your language.
It works great for me in PowerShell:
# Load a sample xml document
$xml = [xml]'<root><div id="post_message_somenumber"/><div id="not_post_message"/><div id="post_message_somenumber2"/></root>'
# Run the xpath selection of all matching div's
$xml.selectnodes('//div[#id[starts-with(.,"post_message")]]')
Result:
id
--
post_message_somenumber
post_message_somenumber2
Or, for just the first match:
# Run the xpath selection of the first matching div
$xml.selectnodes('(//div[#id[starts-with(.,"post_message")]])[1]')
Result:
id
--
post_message_somenumber
I tried xpath='//div[starts-with(#id,
'"post_message_')]' in yql without
success I'm still learning this,
anyone have suggestions
If the problem isn't due to the many nested apostrophes and the unclosed double-quote, then the most likely cause (we can only guess without being shown the XML document) is that a default namespace is used.
Specifying names of elements that are in a default namespace is the most FAQ in XPath. If you search for "XPath default namespace" in SO or on the internet, you'll find many sources with the correct solution.
Generally, a special method must be called that binds a prefix (say "x:") to the default namespace. Then, in the XPath expression every element name "someName" must be replaced by "x:someName.
Here is a good answer how to do this in C#.
Read the documentation of your language/xpath-engine how something similar should be done in your specific environment.
#FindBy(xpath = "//div[starts-with(#id,'expiredUserDetails') and contains(text(), 'Details')]")
private WebElementFacade ListOfExpiredUsersDetails;
This one gives a list of all elements on the page that share an ID of expiredUserDetails and also contains the text or the element Details