extract nested params on query_string

get_query_args_extended.lua

function get_query_args_extended()
  args = ngx.req.get_query_args()
  for k, v in pairs(args) do
    t = {}
    for k2 in string.gmatch(k, "%b[]") do
      table.insert(t,string.sub(k2,2,string.len(k2)-1))
    end
    if #t > 0 then
      -- it has nested params, needs to be transformed
      first = string.sub(k,1,string.find(k,"%[")-1)
      if args[first]==nil or type(args[first])~="table" then
        args[first] = {}
      end
      args[first][t[1]] = v
    end
  end
  return args
end