Create datatable utilities

scripts/lua/modules/datatable_utils.lua

@@ -0,0 +1,59 @@
+--
+-- (C) 2020-21 - ntop.org
+--
+
+local dirs = ntop.getDirs()
+package.path = dirs.installdir .. "/scripts/lua/modules/?.lua;" .. package.path
+
+require "lua_utils"
+local json = require("dkjson")
+
+local datatable_utils = {}
+
+local REDIS_KEY = "ntopng.prefs.%s.table.%s.columns"
+
+local function get_username()
+   local username = _SESSION["user"] or ''
+   if (isNoLoginUser()) then username = 'no_login' end
+
+   return username
+end
+
+---Save the columns visibility inside Redis 
+---@param table_name string The HTML table id
+---@param columns string String containing ids separeted by comma
+function datatable_utils.save_column_preferences(table_name, columns)
+   -- avoid the save of nil value
+   if columns == nil then return end
+tprint(columns)
+   local key = string.format(REDIS_KEY, get_username(), table_name)
+   local cols = split(columns, ",")
+
+   ntop.setPref(key, json.encode(cols))
+end
+
+---Load saved column visibility from Redis
+---@param table_name string The HTML table id
+---@return table
+function datatable_utils.load_saved_column_preferences(table_name)
+   local key = string.format(REDIS_KEY, get_username(), table_name)
+   local columns = ntop.getPref(key)
+
+   if isEmptyString(columns) then
+      return { -1 }
+   end
+
+   return json.decode(columns)
+end
+
+---Check if there are saved visible columns
+---@param table_name string The HTML table id
+---@return boolean
+function datatable_utils.has_saved_column_preferences(table_name)
+   local key = string.format(REDIS_KEY, get_username(), table_name)
+   local columns = ntop.getPref(key)
+
+   return not isEmptyString(columns)
+end
+
+return datatable_utils