How do I use XPath in Nokogiri?

Question

I have not found any documentation nor tutorial for that. Does anything like that exist?

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doc.xpath('//table/tbody[@id="threadbits_forum_251"]/tr')

The code above will get me any table, anywhere, that has a tbody child with the attribute id equal to "threadbits_forum_251". But why does it start with double //? Why there is /tr at the end? See "Ruby Nokogiri Parsing HTML table II" for more details.

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Can anybody tell me how to extract href, id, alt, src, etc., using Nokogiri?

td[3]/div[1]/a/text()' <--- extracts text

How can I extract other things?

Answer 1

Seems you need to read a XPath Tutorial

Your //table/tbody[@id="threadbits_forum_251"]/tr expression means:

• // - Anywhere in your XML document
• table/tbody - take a table element with a tbody child
• [@id="threadbits_forum_251"] - where id attribute are equals to "threadbits_forum_251"
• tr - and take its tr elements

So, basically, you need to know:

• attributes begins with @
• conditions go inside [] brackets

If I correcly understood that API, you can go with doc.xpath("td[3]/div[1]/a")["href"], or td[3]/div[1]/a/@href if there is just one <a> element.