ModStorage #

ModStorage is a per-world, per-mod persistent string key-value store implementing all methods of MetaData.

The granularity of the persisted snapshots is determined by the map_save_interval setting.

Backends #

Two backends are available for ModStorage: JSON and SQLite3.

If the SQLite3 backend is used, it is usually more efficient to leverage the key-value store than to store fully serialized data structures; fully serializing the data takes linear time in the size of the data whereas updating the key-value store only takes linear time in the size of the changes with the SQLite3 backend; for the JSON backend it is irrelevant - it has to fully serialize the data every map save interval anyways, increasing the risk of data loss if writing the file fails due to a hard crash (or freeze) of the Luanti server process.

core.get_mod_storage() #

Must be called at load time.

Returns:

• storage - ModStorage: Private ModStorage object for the currently loading mod

Example #

A basic greeting mod with a persistent greeting might look as follows:

local storage = core.get_mod_storage()

-- Send the greeting to joining players
core.register_on_joinplayer(function(player)
	local greeting = storage:get("greeting")
	if greeting then
		core.chat_send_player(player:get_player_name(), greeting)
	end
end)

-- Allow moderators to change the greeting
core.register_chatcommand("/set_greeting", {
	params = "<greeting>",
	description = "Sets the greeting",
	privs = {server = true},
	func = function(name, param)
		param = param:trim() -- MT-provided string.trim
		storage:set_string("greeting", param)
		return true, param == "" and "Greeting cleared." or "Greeting set."
	end
})