xpath find if node exists

Question

Using a xpath query how do you find if a node  tag  exists at all   For example if I needed to make sure a website page has the correct basic structure like  html body and  html head title

User · Answer

Try the following expression  boolean path-to-node

User · Answer

Patrick is correct  both in the use of the xsl if  and in the syntax for checking for the existence of a node  However  as Patrick s response implies  there is no xsl equivalent to if-then-else  so if you are looking for something more like an if-then-else  you re normally better off using xsl choose and xsl otherwise  So  Patrick s example syntax will work  but this is an alternative    lt xsl choose gt    lt xsl when test   html body  gt body node exists lt  xsl when gt    lt xsl otherwise gt body node missing lt  xsl otherwise gt   lt  xsl choose gt

User · Answer

Might be better to use a choice  don t have to type  or possibly mistype  your expressions more than once  and allows you to follow additional different behaviors   I very often use count  html body    0  as the specific number of nodes is more interesting than the set   For example    when there is unexpectedly more than 1 node that matches your expression    lt xsl choose gt       lt xsl when test   html body  gt            lt  -- Found the node s  -- gt       lt  xsl when gt       lt  -- more xsl when here  if needed -- gt       lt xsl otherwise gt            lt  -- No node exists -- gt       lt  xsl otherwise gt   lt  xsl choose gt

User · Answer

A variation when using xpath in Java using count     int numberofbodies   Integer parseInt  String  xPath evaluate  count  html body    doc    if  numberofbodies  0           body node missing

User · Answer

I work in Ruby and using Nokogiri I fetch the element and look to see if the result is nil   require  nokogiri   url    http   somthing com resource   resp   Nokogiri  XML open url    first name   resp xpath   movies actors actor 1  first-name    puts  first-name not found  if first name nil

User · Answer

lt xsl if test  xpath-expression  gt     lt  xsl if gt    so for example   lt xsl if test   html body  gt body node exists lt  xsl if gt   lt xsl if test  not  html body   gt body node missing lt  xsl if gt

[xslt] xpath find if node exists

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