This is a really ugly hack, but it works well enough for me to do as a one-off to convert a bunch of data from html strings into rich-text objects. I had originally stored my data in the long_text column as an html string, and now I want to store the raw JSON version of the same data in the rich_text column.
This is really just a demo of the idea, but if it helps anyone, I'll be happy that it does.