only show files of specific filetype

[exformation]

I'm trying to write a toggle that will filter out all files that aren't of the current filetype.

I've messed around with various forms of the following, which is attempting to hide anything that isn't a lua file, but can't get it working:

filesystem = {
  filtered_items = {
    hide_by_pattern = { '!(*.lua)' },
  }
}

I've also tried this to no avail:

never_show_by_pattern = { '*' },
always_show_by_pattern = { '*.lua' },

I'm also not sure how I'd implement this as a toggle once I get it working.

[MeneerJansen]

Looks like we can't use regex in lua. See: https://stackoverflow.com/questions/6192137/how-to-write-this-regular-expression-in-lua

Maybe the developer of NeoTree can tell us if we can use the expression "not" which is sometimes expressed as ! (exclamation mark). Or may be there's a command like only_show_by_pattern?

I don't speak lua so I don't know pattern matching works in lua.

P.S. Thank you for your post. I didn't know about hide_by_pattern and I used your code abouve to hide backup files in Linux (which end in ~) like so:

-- Let NeoTree hide ~ files (backup files in Linux).
require('neo-tree').setup {
  filesystem = {
    filtered_items = {
      hide_by_pattern = {"*~"},       
    },
},}