如何使用XPath3表达式从含多元素的XML标签中获取特定元素

Got it, let's fix that XPath expression for you. Your current approach has a syntax error in how you're targeting the attribute, and we can simplify this to directly select the elements you need.

First, let's break down the issue with your existing code:

• The expression .//*:@success uses invalid XPath syntax. To target attributes, you need to use the @ prefix before the attribute name, and wrap the condition in a predicate ([]).

The Correct XPath #

To select all elements anywhere in your XML that have a success attribute with the exact value "N", use this XPath:

.//*[@success='N']

Let's break this down:

• .//*: Selects all descendant elements starting from the current context node (so it searches the entire XML tree under your payload).
• [@success='N']: Filters those elements to only include ones where the success attribute equals "N".

Using with the xpath3 Function #

Depending on what you need to do, adjust the third parameter of the xpath3 function:

1. To get the matching elements as a nodeset:

   #[xpath3('.//*[@success="N"]', payload, "NODESET")]
   

   This will return all elements that meet the condition, which you can then process further.

2. To check if any such element exists (return a boolean):

   #[xpath3('exists(.//*[@success="N"])', payload, "BOOLEAN")]
   

   This will return true if there's at least one element with success="N", otherwise false.

3. To get a specific attribute or value from the matching elements:
   If you wanted to, say, get the type attribute of the matching elements, you could use:

   #[xpath3('.//*[@success="N"]/@type', payload, "STRING")]
   

   This would return the type attribute value (like "RETURN" from your sample XML) as a string.

Example with Your Sample XML #

If your payload is:

<REQUEST type="RETURN" success="N"/>

The XPath .//*[@success='N'] will select the entire <REQUEST> element, which is exactly what you're looking for.

内容的提问来源于stack exchange，提问作者Devdas Sandbhor