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---
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layout: post
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title: Drilling down into XML snippets
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excerpt: The new "xpath()" table-valued SQL function.
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---
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*(This change is in [**v0.10.0+**](https://github.com/tstack/lnav/releases/tag/v0.10.0))*
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XML snippets in log messages can now be queried using the
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[`xpath()`](https://docs.lnav.org/en/latest/sqlext.html#xpath-xpath-xmldoc)
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table-valued SQL function. The function takes an
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[XPath](https://developer.mozilla.org/en-US/docs/Web/XPath), the XML snippet
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to be queried, and returns a table with the results of the XPath query.
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For example, given following XML document:
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```xml
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<msg>Hello, World!</msg>
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```
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Extracting the text value from the `msg` node can be done using the following
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query:
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```sql
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SELECT result FROM xpath('/msg/text()', '<msg>Hello, World!</msg>')
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```
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Of course, you won't typically be passing XML values as string literals, you
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will be extracting them from log messages. Assuming your log format already
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extracts the XML data, you can do a `SELECT` on the log format table and join
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that with the `xpath()` call. Since it can be challenging to construct a
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correct `xpath()` call, lnav will suggest calls for the nodes it finds in any
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XML log message fields. The following asciicast demonstrates this flow:
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<script id="asciicast-x89mrk8JPHBmB4pTbaZvTt8Do"
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src="https://asciinema.org/a/x89mrk8JPHBmB4pTbaZvTt8Do.js"
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async>
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</script>
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The implementation uses the [pugixml](https://pugixml.org) library.
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