Is there a way to generate a random number with xpath? My input is any well-formed xml, the output should be a random integer of a given length.
I usually achieve it with any coding or xslt but I'm struggling to find a working xpath expression.
XPath 3.1 has a function fn:random-number-generator().
In earlier XPath versions you'll need to improvise.
When asking XPath questions please say which version you are using - the ancient XPath 1.0 is still in widespread use so it's impossible to make guesses.
Since this question is the top google result, I'll say in XPath 3.1, Mr. Kay's answer can be achieved like this:
Say you want a random element. Count the elements:
<xsl:variable name="random-upper-limit" select="count(/myroot/mypath/myelement)"/>
Then get a random index number:
<xsl:variable name="my-random-number" select="random-number-generator()['next']?permute(1 to $random-upper-limit)[1]"/>
Related
I have an element with three occurences on the page. If i match it with Xpath expression //div[#class='col-md-9 col-xs-12'], i get all three occurences as expected.
Now i try to rework the matching element on the fly with
substring-before(//div[#class='col-md-9 col-xs-12'], 'Bewertungen'), to get the string before the word "Bewertungen",
normalize-space(//div[#class='col-md-9 col-xs-12']), to clean up redundant whitespaces,
normalize-space(substring-before(//div[#class='col-md-9 col-xs-12'] - both actions.
The problem with last three expressions is, that they extract only the first occurence of the element. It makes no difference, whether i add /text() after matching definition.
I don't understand, how an addition of normalize-space and/or substring-before influences the "main" expression in the way it stops to recognize multiple occurences of targeted element and gets only the first. Without an addition it matches everything as it should.
How is it possible to adjust the Xpath expression nr. 3 to get all occurences of an element?
Example url is https://www.provenexpert.com/de-de/jazzyshirt/
The problem is that both normalize-space() and substring-before() have a required cardinality of 1, meaning can only accept one occurrence of the element you are trying to normalize or find a substring of. Each of your expressions results in 3 sequences which these two functions cannot process. (I probably didn't express the problem properly, but I think this is the general idea).
In light of that, try:
//div[#class='col-md-9 col-xs-12']/substring-before(normalize-space(.), 'Bewertung')
Note that in XPath 1.0, functions like substring-after(), if given a set of three nodes as input, ignore all nodes except the first. XPath 2.0 changes this: it gives you an error.
In XPath 3.1 you can apply a function to each of the nodes using the apply operator, "!": //div[condition] ! substring-before(normalize-space(), 'Bewertung'). That returns a sequence of 3 strings. There's no equivalent in XPath 1.0, because there's no data type in XPath 1.0 that can represent a sequence of strings.
In XPath 2.0 you can often achieve the same effect using "/" instead of "!", but it has restrictions.
When asking questions on StackOverflow, please always mention which version of XPath you are using. We tend to assume that if people don't say, they're probably using 1.0, because 1.0 products don't generally advertise their version number.
I was just wondering if there is a shorter way of writing an XPath query to find all HREF values containing at least one of many search values?
What I currently have is the following:
//a[contains(#href, 'value1') or contains(#href, 'value2')]
But it seems quite ugly, especially if I were to have more values.
First of all, in many cases you have to live with the "ugliness" or long-windedness of expressions if only XPath 1.0 is at your disposal. Elegance is something introduced with version 2.0, I'd daresay.
But there might be ways to improve your expression: Is there a regularity to the href attributes you'd like to find? For instance, if it is sufficient as a rule to say that the said href attribute values must start with "value", then the expression could be
//a[starts-with(#href,'value')]
I know that "value1" and "value2" are most probably not your actual attribute values but there might be something else that uniquely identifies the group of a elements you're after. Post your HTML input if this is something you want us to help you with.
Personally, I do not find your expression ugly. There is just one or operator and the expression is quite short and readable. I take
if I were to have more values.
to mean that currently, there are only two attribute values you are interested in and that your question therefore is a theoretical one.
In case you're using XPath 2 and would like to have exact matches instead of also matches only containing part of a search value, you can shorten with
//a[#href = ('value1', 'value2')]
For contains() this syntax wouldn't work as the second argument of contains() is only allowed to be 0 or 1 value.
In XPath 2 you could also use
//a[some $s in ('value1', 'value2') satisfies contains(#href, $s)]
or
//a[matches(#href, "value1|value2")]
This question regards XPath expressions.
I want to find the average of the length of all URLs in a Web page, that point to a .pdf file.
So far I have constructed the following expression, but it does not work:
sum(string-length(string(//a/#href[contains(., ".pdf")]))) div
count(//a/#href[contains(., ".pdf")])
Any help will be appreciated!
You will need XPath 2.0.
For calculating the sum of the string lengths, you will need either
need a concatenated string of all #hrefs to apply to string-lenght($string as xs:string) (which only allows a single string as parameter), but concat(...) only takes an arbitrary number of atomar strings, not a sequence of those; or
apply string-length(...) on every #href as #Navin Rawat proposed - but using arbitrary functions in axis steps is a new feature of XPath 2.0.
If using XPath 2.0, there are functions avg(...) and ends-with(...) which help you in stripping down the expression to
avg(//a/#href[ends-with(., '.pdf')]/string-length())
If you have to stick with XPath 1.0, all you can do is using my expression below to fetch the URLs and calculate the average outside XPath.
Anyway, the subexpression you proposed will fail at URLs like http://example.net/myfile.pdf.txt. Only compare the end of the URL:
//a[#href[substring(., string-length(.) - 3) = '.pdf']]/#href
And you missed a path step for the attribute, so you've been trying to average the string length of the link names right now.
Please put something like:
sum(//a/#href[contains(.,'.pdf')]/string-length()) div count(//a/#href[contains(.,'.pdf')])
In an XML file I have a number of date fields. I need to find out which one is the highest value. Unfortunately, I have to use XPath 1.0, so there's not an easy way to do it.
I started out with this XML:
<root>
<value>20120103</value>
<value>20130103</value>
<value>20120101</value>
<value>20140103</value>
<value>20100103</value>
</root>
From this, I can get the highest value with this xpath statement:
/root/value[not(text() <= preceding-sibling::value/text()) and not(text() <=following-sibling::value/text
())]
However, the real XML I'm working with got date fields like this:
<root>
<value>2012-01-03</value>
<value>2013-01-03</value>
<value>2012-01-01</value>
<value>2014-01-03</value>
<value>2010-01-03</value>
</root>
To execute the same XPath, I have to use substring and concat to remove the minus signs. However, the application I'm using the XPath in and the Oxygen XML editor tell me that concat and substring are no Xpath 1.0 functions (although several pages tell me that they are...)
When I tell Oxygen that it's Xpath 2.0, I can get the values with this statement:
/root/value[not(concat(concat(substring(text(),1,4),substring(text(),6,2)),substring(text(),9,2)) <= preceding-sibling::value/concat(concat(substring(text(),1,4),substring(text(),6,2)),substring(text(),9,2))) and not
(concat(concat(substring(text(),1,4),substring(text(),6,2)),substring(text(),9,2)) <=following-sibling::value/concat(concat(substring(text(),1,4),substring(text(),6,2)),substring(text(),9,2)))]
Any ideas why it isn't working with Xpath 1.0 and how I can get around this?
Edit:
I thought I was getting closer by using translate to remove the minus signs:
/root/value[not(translate(text(),'-','') <= translate(preceding-sibling::value/text(),'-','')) and not(translate(text(),'-','') <=translate(following-sibling::value/text(),'-','')
)]
but for one or another reasons this produces two values:
2013-01-03
2014-01-03
While I would only expect the second one
This cannot be determined with a single XPath 1.0 expression because:
In XPath 1.0 there isn't an < or > operator for strings.
Although one can use translate() to remove the hyphens from the context node, it isn't possible in a single XPath 1.0 expression to compare this with all other values, each of which has undergone the same translation.
XPath 2.0 solution:
max(/*/*/xs:date(.))
Actually, your first XPath
/root/value[not(text() <= preceding-sibling::value/text()) and not(text() <=following-sibling::value/text())]
should work fine in both cases.
As long as the format is in year, month, day order with leading zeros...
However, it will not work, if there are duplicated days, so better use:
(/root/value[not(text() < preceding-sibling::value/text()) and not(text() < following-sibling::value/text())])[1]
I used Firebug's Inspect Element to capture the XPath in a webpage, and it gave me something like:
//*[#id="Search_Fields_profile_docno_input"]
I used the Bookmarklets technique in IE to capture the XPath of the same object, and I got something like:
//INPUT[#id='Search_Fields_profile_docno_input']
Notice, the first one does not have INPUT instead has an asterisk (*). Why am I getting different XPath expressions? Does it matter which one I use for my tests like:
Selenium.Click(//*[#id="Search_Fields_profile_docno_input"]);
OR
Selenium.Click(//INPUT[#id='Search_Fields_profile_docno_input']);
*[Id=] denotes that it can be any element while the second one clearly mentions selenium to look ONLY for INPUT fields which have id as Search_Fields_profile_docno_input. The second xpath is better due to following reasons
It takes more time to find the element using * as IDs of all elements should be matched.
If your HTML code is not "well written" there could be other elements which have the same id and this could cause your test to fail.
The first one matches any element with a matching ID, whereas the second one restricts matches to <input> elements. If these were CSS expressions it'd be the difference between #Search_Fields_profile_docno_input and input#Search_Fields_profile_docno_input.
Assuming you only use this ID once in your web page, the two XPaths are effectively equivalent. They'll both match the <input id="Search_Fields_profile_docno_input"> element and no other.
There are some good answers to your "why?" question here, but for Selenium use, there's an even better alternative. Since your page element has an ID attribute, use Selenium's ID locator instead of XPath or CSS:
Selenium.Click("id=Search_Fields_profile_docno_input");
This will go directly to the element, and will run quicker than just about any other locator. Note that the syntax is id=value, not id="value".
Given any element in your document, there's an infinite number of XPath expressions that will select it uniquely. Therefore it's entirely reasonable for two different products to generate two different paths.
Google has just released Wicked Good XPath - A rewrite of Cybozu Lab's famous JavaScript-XPath. Link: https://code.google.com/p/wicked-good-xpath/ The rewritten version is 40% smaller and about %30 faster than the original implementation.
You can check this out and replace the one being used in Selenium.