Скачать или смотреть How to Find XML Values Using XPath with Grandparent Attributes

Discover how to effectively navigate XML elements using `XPath`, focusing on querying values based on attributes of parent and grandparent elements.
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This video is based on the question https://stackoverflow.com/q/67028904/ asked by the user 'HerrimanCoder' ( https://stackoverflow.com/u/1136267/ ) and on the answer https://stackoverflow.com/a/67029054/ provided by the user 'quaabaam' ( https://stackoverflow.com/u/9541862/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Solving XML Attribute Navigation with XPath

Navigating through XML can sometimes be a challenging task, especially when you need to extract specific values based on their relationships to parent and grandparent elements. In this guide, we will explore how to effectively use XPath to find the value of a <property> element by looking up its parent and grandparent attributes.

The Problem

You have a chunk of XML that contains various elements and attributes. Your goal is to retrieve the value of a <property> element that meets specific criteria:

The <property> must have an id of MyPropID.

Its parent <option> must have a grandparent <category> that has an id of MyCatID.

An example of the relevant XML structure is as follows:

[[See Video to Reveal this Text or Code Snippet]]

However, your initial XPath attempt:

[[See Video to Reveal this Text or Code Snippet]]

brings back the entire <category> element, rather than just the value The magic value I need.

The Solution

To correctly target the desired value, you need to reverse the approach of your XPath query. Instead of starting from the <property> element, begin with the <category> element where you specify the required id and navigate to the <property>.

Updated XPath Query

Here's the modified XPath:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Query

//category[@ id='MyCatID']: This part of the query finds the <category> element with the specified id.

/option: This indicates you want to navigate to the child <option> elements associated with that category.

/property[@ id='MyPropID']: Finally, this one retrieves the <property> element that possesses the id of MyPropID.

Summary

Using this structured approach allows you to isolate the required element efficiently:

Identify the Grandparent: Start with the grandparent attribute to filter which node you want.

Navigate Down: Move down the XML structure to reach the desired child attribute.

Combine Conditions: Ensure all conditions are satisfied in a single expression for optimal results.

By implementing this method, you can successfully extract the specific value you're looking for without retrieving unnecessary elements.

Now, give this updated XPath technique a try, and you should be able to pull out the magic value you need with ease!