If you have a huge JSON file then you may consider using jaxon library instead.
Take a look at example from it’s readme file:
"large_file.json"
|> File.stream!()
|> Jaxon.Stream.from_enumerable()
|> Jaxon.Stream.query([:root, "users", :all, "metadata"])
|> Stream.map(&(&1["username"],",",&1["email"],"\n"))
|> Stream.into(File.stream!("large_file.csv"))
|> Stream.run()
