A handler is a function that takes a http request, and returns the response. Middleware is a function that takes a handler (so a request->response function) and returns a new handler. So you wrap the existing handler in a call to the parse-edn-body middleware.
photos.server=> (run)
CompilerException java.lang.RuntimeException: Unable to resolve symbol: run in this context, compiling:(/private/var/folders/rc/y5p0pv054xb20rtgwhzx5pzc0000gn/T/form-init1884776825299031157.clj:1:1)
Look carefully at the output when the REPL boots. Unable to resolve symbol: run is usually a symptom that there’s an error in the code, so things aren’t loaded properly.
If you can’t figure it out then push your app to github and I’ll have a look.