Subfetches allow you to use content from other URLs to populate
the current URL's record. We may have a site about articles, where
each article has a web page describing the article, and a link to a
PDF of the actual article. We'd like searches that match article
contents to take us to the web page, not the article PDF itself.
If the web page has a meta header called "pdfLink" with a URL to the article PDF, we can use the body of the PDF as a replacement for the web page's body with two Data from Field rules like this:
First Data from Field rule:
Meta Field ->
Second Data from Field rule:
Subfetch Data from Field rule fetches the URL specified in
the pdfLink header. While this grabs the PDF, it doesn't
change anything on its own. We then pull from the PDF's text output,
and use that as the
Body of the current web page.