How to find the parent node by matching text using XPath - ruby

Question

I have some XML:
<sys>
<lang>
<employee>
<name>Employee 1</name>
<code>4fdaa994-7015-4ec1-b365-de4ee0279966</code>
</employee>
<employee>
<name>Employee 2</name>
<code>1d960bdc-0853-49af-bb83-18cf92493897</code>
</employee>
</lang>
</syz>
How can I search and get the employee node where name ="Employee 1"?
I tried this but it didn't work:
obj.xpath("//sys/lang[/employee/name = 'Employee 1']")

Answer 1

This XPath
/sys/lang/employee[name = 'Employee 1']
will select the employee element whose name is Employee 1.
Why might OP be getting an "Invalid expression" using the above XPath?
Transcription error.
Resolution: Use copy and paste.
Single quotes around single quotes.
Resolution: Use outer double quotes: "/sys/lang/employee[name = 'Employee 1']"
Smart quotes.
Resolution: Replace ‘ and ’ with single quote '.
Misinterpretation of error message.
Resolution: Carefully check any line number mentioned in error, or carve away surrounding code as much as possible, and see if error goes away.
If none of the above possibilities apply, post a MCVE (Minimal, Complete, and Verifiable Example, including the provided XPath and the calling code -- the complete in MCVE) that produces the invalid expression error, and someone will likely immediately spot the problem.

Answer 2

I'm a big fan of using CSS over XPath for readability reasons. Nokogiri implements a number of jQuery's extensions to make it easier to use CSS for things we'd usually use XPath for.
I'd do it this way:
require 'nokogiri'
doc = Nokogiri::XML(<<EOT)
<sys>
<lang>
<employee>
<name>Employee 1</name>
<code>4fdaa994-7015-4ec1-b365-de4ee0279966</code>
</employee>
<employee>
<name>Employee 2</name>
<code>1d960bdc-0853-49af-bb83-18cf92493897</code>
</employee>
</lang>
</syz>
EOT
emp1 = doc.at('employee name:contains("Employee 1")') # => #<Nokogiri::XML::Element:0x3ffed05285b4 name="name" children=[#<Nokogiri::XML::Text:0x3ffed05283d4 "Employee 1">]>
emp1.to_xml # => "<name>Employee 1</name>"
emp1.parent.to_xml # => "<employee>\n <name>Employee 1</name>\n <code>4fdaa994-7015-4ec1-b365-de4ee0279966</code>\n </employee>"
Also note, it's not good practice to define the full path in the selector for a node. If the HTML or XML changes the structure that selector will break. Instead, find useful landmarks and hop from one to the next. That way your selector is more likely to survive changes in the markup. I only care about finding the appropriate <employee>...<name> combination, not those two tags embedded under <sys> and <lang>.
Sometimes an alternate way of getting to the information you want is to use search and look at a particular index:
doc.search('employee').first.to_xml # => "<employee>\n <name>Employee 1</name>\n <code>4fdaa994-7015-4ec1-b365-de4ee0279966</code>\n </employee>"
Or:
doc.at('employee').to_xml # => "<employee>\n <name>Employee 1</name>\n <code>4fdaa994-7015-4ec1-b365-de4ee0279966</code>\n </employee>"
at('some selector') is equivalent to search('some selector').first.