Скачать или смотреть Extracting Data from MARCXML Using XMLStarlet

Learn how to efficiently extract specific data from MARCXML files using `XMLStarlet`. This guide provides a clear solution to query MARCXML and retrieve desired outputs.
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Extracting Data from MARCXML Using XMLStarlet

If you're dealing with MARCXML files, you might find yourself in a situation where you need to extract specific pieces of information based on certain criteria. In this post, we'll show you how to use XMLStarlet, a command-line XML toolkit, to extract data from MARCXML files effectively.

The Problem: Extracting Specific Elements

Let's say you have a MARCXML file, foo.xml, structured like this:

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

In this structure, you're interested in extracting the content of <marcxml:subfield code="a"> that corresponds to a <marcxml:subfield code="2"> containing the string 'bk'. In our case, the output you want is 89.52.

The Solution: Using XMLStarlet

To achieve this with XMLStarlet, follow the steps below.

Command to Use

You can use the following command:

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

Breakdown of the Command

Let’s break down what this command does:

xmlstarlet sel: Initiates the selection process.

-N marcxml="http://www.loc.gov/MARC21/slim": Defines a namespace for MARCXML, allowing XMLStarlet to properly understand which elements to access.

-t: Specifies the template mode. This is needed for selecting elements based on certain conditions.

-v: Fetches the value of specific XML nodes.

'//marcxml:subfield[@ code="2"][text()="bk"]/following-sibling::marcxml:subfield[@ code="a"]':

This XPath expression does the following:

Looks for the <marcxml:subfield> with code="2" whose text content is bk.

From that element, it accesses the following sibling <marcxml:subfield> element that has code="a".

-nl: Specifies that each output value should be followed by a newline.

What Happens Next?

When you run this command, XMLStarlet successfully retrieves the required data from the MARCXML file, returning:

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

Conclusion

Using XMLStarlet to extract data from MARCXML can streamline your workflow, especially when dealing with large and complex XML files. With the right command, you can target and retrieve specific pieces of information needed for your projects.

We hope this guide has made it clear how to work with XMLStarlet in extracting data from MARCXML files. If you have further questions or need additional examples, feel free to reach out!