nokogiri multiple css classes

How is it possible to select an html element that have two classes?

For example, how to select the element <p> bellow in an HTML document (given that it has two css classes) class='class1 class2'.

I tried to use the following:

• doc.xpath("//p[@class~='class1 class2']"开发者_开发百科)
• doc.xpath("//p[@class~='class1']|[@class~='class2']")
• doc.xpath("//p[@class~='class1',@class~='class2']")
• doc.xpath("//p[contains(concat(' ', @class, ' '), ' class1 ') && contains(concat(' ',@class, ' '), ' class2 ')]")

but without success.

Thanks in advance

Finally I found the RIGHT way to search multiple css classes with nokogiri (libxml) :

doc.xpath('//p[contains(@class, "class1") and contains(@class, "class2")]')

It's not perfect, because if <p> contains classes such as class10 and class20 the element will be selected, but for now it's enough for what I need. If you have more suggestions they are welcome!

Update

Here is a better solution to this problem using css only :

doc.css('p.class1.class2')

Thanks to Aaron Patterson :-)