I am trying to build a simple search-engine using HtmlAgilityPack and Xpath with C# (.NET 4).
I want to find every node containing a userdefined searchword, but I can't seem to get the XPath right.
For Example:
<HTML>
<BODY>
<H1>Mr T for president</H1>
<div>We believe the new president should be</div>
<div>the awsome Mr T</div>
<div>
<H2>Mr T replies:</H2>
<p>I pity the fool who doesn't vote</p>
<p>for Mr T</p>
</div>
</BODY>
</HTML>
If the specified searchword is "Mr T" I'd want the following nodes: <H1>, The second <div>, <H2> and the second <p>.
I have tried numerous variants of doc.DocumentNode.SelectNodes("//text()[contains(., "+ searchword +")]"); but I always seem to wind up with every single node in the entire DOM.
Any hints to get me in the right direction would be very appreciated.
Use:
//*[text()[contains(., 'Mr T')]]
This selects all elements in the XML document that have a text-node child which contains the string 'Mr T'.
This can also be written shorter as:
//text()[contains(., 'Mr T')]/..
This selects the parent(s) of any text node that contains the string 'Mr T'.
According to Xpath, if you want to find a specific keyword you need to follow the format ("keyword" is the word you like to search) :
//*[text()[contains(., 'keyword')]]
You have to follow the same format as above in C#, keyword is the string variable you call:
doc.DocumentNode.SelectNodes("//*[text()[contains(., '" + keyword + "')]]");
Use the following:
doc.DocumentNode.SelectNodes("//*[contains(text()[1], " + searchword + ")]")
This selects all elements (*) whose first text child (text()[1]) contains the searchword.
Case-insensitive solution:
var xpathForFindText =
"//*[text()[contains(translate(., 'ABCDEFGHIJKLMNOPQRSTUVWXYZ', 'abcdefghijklmnopqrstuvwxyz'), '" + lowerFocusKwd + "')]]";
var result=doc.DocumentNode.SelectNodes(xpathForFindText);
Note:
Be careful, because the lowerFocusKwd must not contain the following character, because the xpath will be in bad format:
'
Related
This may be an easy question, I'm new to this.
I'm trying to get the data within this div
<div class="search-results-listings
" vocab="http://schema.org/" typeof="SearchResultsPage">
response.xpath("//div[#class='search-results-listings\n']")
and
response.xpath("//div[#class='search-results-listings\n ']")
are returning empty arrays
You can use XPath's contains:
response.xpath("//div[contains(#class, 'search-results-listings')]")
Basically I need to scrape some text that has nested tags.
Something like this:
<div id='theNode'>
This is an <span style="color:red">example</span> <b>bolded</b> text
</div>
And I want an expression that will produce this:
This is an example bolded text
I have been struggling with this for hour or more with no result.
Any help is appreciated
The string-value of an element node is the concatenation of the string-values of all text node descendants of the element node in document order.
You want to call the XPath string() function on the div element.
string(//div[#id='theNode'])
You can also use the normalize-space function to reduce unwanted whitespace that might appear due to newlines and indenting in the source document. This will remove leading and trailing whitespace and replace sequences of whitespace characters with a single space. When you pass a nodeset to normalize-space(), the nodeset will first be converted to it's string-value. If no arguments are passed to normalize-space it will use the context node.
normalize-space(//div[#id='theNode'])
// if theNode was the context node, you could use this instead
normalize-space()
You might want use a more efficient way of selecting the context node than the example XPath I have been using. eg, the following Javascript example can be run against this page in some browsers.
var el = document.getElementById('question');
var result = document.evaluate('normalize-space()', el, null ).stringValue;
The whitespace only text node between the span and b elements might be a problem.
Use:
string(//div[#id='theNode'])
When this expression is evaluated, the result is the string value of the first (and hopefully only) div element in the document.
As the string value of an element is defined in the XPath Specification as the concatenation in document order of all of its text-node descendants, this is exactly the wanted string.
Because this can include a number of all-white-space text nodes, you may want to eliminate contiguous leading and trailing white-space and replace any such intermediate white-space by a single space character:
Use:
normalize-space(string(//div[#id='theNode']))
XSLT - based verification:
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
<xsl:output omit-xml-declaration="yes" indent="yes"/>
<xsl:template match="/">
"<xsl:copy-of select="string(//div[#id='theNode'])"/>"
===========
"<xsl:copy-of select="normalize-space(string(//div[#id='theNode']))"/>"
</xsl:template>
</xsl:stylesheet>
when this transformation is applied on the provided XML document:
<div id='theNode'> This is an
<span style="color:red">example</span>
<b>bolded</b> text
</div>
the two XPath expressions are evaluated and the results of these evaluations are copied to the output:
" This is an
example
bolded text
"
===========
"This is an example bolded text"
If you are using scrapy in python, you can use descendant-or-self::*/text(). Full example:
txt = """<div id='theNode'>
This is an <span style="color:red">example</span> <b>bolded</b> text
</div>"""
selector = scrapy.Selector(text=txt, type="html") # Create HTML doc from HTML text
all_txt = selector.xpath('//div/descendant-or-self::*/text()').getall()
final_txt = ''.join( _ for _ in all_txt).strip()
print(final_txt) # 'This is an example bolded text'
How about this :
/div/text()[1] | /div/span/text() | /div/b/text() | /div/text()[2]
Hmmss I am not sure about the last part though. You might have to play with that.
normal code
//div[#id='theNode']
to get all text but if they become split then
//div[#id='theNode']/text()
Not sure but if you provide me the link I will try
I am trying to get a string before '--' within a paragraph in an html page using the xpath and send it to yql
for example i want to get the date from the following article:
<div>
<p>Date --- the body of the article</p>
</div>
I tried this query in yql:
select * from html where url="article url" and xpath="//div/p/text()/[substring-before(.,'--')]"
but it does not work.
how can I get the date of the article which is before the '--'
You can simply use:
substring-before(//div/p,'--')
Use:
substring-before(/div/p/text(), '--')
This XPath expression evaluates to the string immediately preceding '--' in the first text node in the XML document, that is a child of a p that is a child of the div top element.
In case you want to get this value for every such text node, you have to use an expression like:
substring-before((//div/p/text())[$k], '--')
and evaluate this expression $N times, for $k = 1,2, ..., $N
where $N is count(//div/p/text())
Do note: Try to avoid using the // XPath pseudo-operator always when the structure of the XML document is statically known. Using // usually results in big inefficiency (O(N^2)) that are felt especially painful on big XML documents.
I am trying to find a way to search for a string within nodes, but excluding ythe content of some subelements of those nodes. Plain and simple, I want to search for a string in paragraphs of a text, excluding the footnotes which are children elements of the paragraphs.
For example,
My document being:
<document>
<p n="1">My text starts here/</p>
<p n="2">Then it goes on there<footnote>It's not a very long text!</footnote></p>
</document>
When I'm searching for "text", I would like the Xpath / XQuery to retrieve the first p element, but not the second one (where "text" is contained only in the footnote subelement).
I have tried the contains() function, but it retrieves both p elements.
Any help would be much appreciated :)
I want to search for a string in
paragraphs of a text, excluding the
footnotes which are children elements
of the paragraphs
An XPath 1.0 - only solution:
Use:
//p//text()[not(ancestor::footnote) and contains(.,'text')]
Against the following XML document (obtained from yours but added p s within a footnote to make this more interesting):
<document>
<p n="1">My text starts here/</p>
<p n="2">Then it goes on there
<footnote>It's not a very long text!
<p>text</p>
</footnote>
</p>
</document>
this XPath expression selects exactly the wanted text node:
My text starts here/
//p[(.//text() except .//footnote//text())[contains(., 'text')]]
/document/p[text()[contains(., 'text')]] should do.
For the record, as a complement to the other answers, I've found this workaround that also seems to do the job:
//p[contains(child::text()|not(descendant::footnote), "text")]
I'd like to use Nokogiri to extract all nodes in an element that contain a specific attribute name.
e.g., I'd like to find the 2 nodes that contain the attribute "blah" in the document below.
#doc = Nokogiri::HTML::DocumentFragment.parse <<-EOHTML
<body>
<h1 blah="afadf">Three's Company</h1>
<div>A love triangle.</div>
<b blah="adfadf">test test test</b>
</body>
EOHTML
I found this suggestion (below) at this website: http://snippets.dzone.com/posts/show/7994, but it doesn't return the 2 nodes in the example above. It returns an empty array.
# get elements with attribute:
elements = #doc.xpath("//*[#*[blah]]")
Thoughts on how to do this?
Thanks!
I found this here
elements = #doc.xpath("//*[#*[blah]]")
This is not a useful XPath expression. It says to give you all elements that have attributes that have child elements named 'blah'. And since attributes can't have child elements, this XPath will never return anything.
The DZone snippet is confusing in that when they say
elements = #doc.xpath("//*[#*[attribute_name]]")
the inner square brackets are not literal... they're there to indicate that you put in the attribute name. Whereas the outer square brackets are literal. :-p
They also have an extra * in there, after the #.
What you want is
elements = #doc.xpath("//*[#blah]")
This will give you all the elements that have an attribute named 'blah'.
You can use CSS selectors:
elements = #doc.css "[blah]"