What are the steps involved in saving data and retrieving them for gameplay? (SOLVED)

[ashherb2u]

How do I save stuff like number of coins on the player’s device and how do I retrieve it for a later session and how do I make it work for all platforms?

[LosJustos]

Take a look at sys.load (https://www.defold.com/ref/sys/#sys.load:filename) and sys.save (https://www.defold.com/ref/sys/#sys.save:filename-table)

[david.yarbrough]

There are some additional tips here that are helpful. I was having trouble saving data on Android before I found this topic:

Android Manifest permissions not compiling (DEF-1916)

Excellent! Using sys.save(“save_file”, save_data) on Android will try to write to a folder outside of the application-specific folders, and this requires the WRITE_EXTERNAL_STORAGE permission. You should always use sys.get_save_file() first to get a “safe” location to save/load data from.

[Pkeod]

DefSave was made to make this easier.

DefSave

[ashherb2u]

local gamedata = {}
local file_path = sys.get_save_file("my project", "gamedata")
	
local function broadcast()
	msg.post("level:/controller#controller", "shields", {shields = shields})
	msg.post("level:/controller#controller", "coins",{coins = coins})
	msg.post("level:/gui#ui", "highscore",{highscore = highscore})	
	msg.post("level:/plane#plane", "missiles",{missiles = missiles})
end				

function init(self)
	local game_data= sys.load("gamedata")
	if #game_data == 0 then
		shields = 3-- as shown below
		coins = 0
		highscore = 0
		missiles = 5
		broadcast()
	else 
		shields = game_data[1]--post to controller
		coins = game_data[2] --post to controller
		highscore = game_data[3] -- post a message to the score gui
		missiles = game_data[4]	-- post a message to the plane go
		broadcast()
	end
end	
	
function on_message(self, message_id, message, sender)
	if message_id == hash("shields") then
		shields = shields + message.shields
	elseif message_id == hash("coins") then
		coins = coins + message.coins
	elseif message_id == hash("highscore")	then
		highscore = highscore + message.highscore
	elseif message_id == hash("missiles") then
		missiles = missiles + message.missiles
	end
end

function final(self)
	table.insert(gamedata, 1, shields)
	table.insert(gamedata, 2, coins)
	table.insert(gamedata, 3, highscore)
	table.insert(gamedata, 4, missiles)
	sys.save(file_path, 'gamedata')
					
end						

whenever i restart the session the length of gamedata is always zero how do it fix it

[Gmanicus]

@ashherb2u

local game_data= sys.load("gamedata")

This line appears to be your problem. I believe Sys.load needs the filepath to find it. You could accomplish this by just inserting your file_path variable there:

local game_data= sys.load(file_path)

[britzl]

@ashherb2u

sys.save(file_path, ‘gamedata’)

This will save the string “gamedata” to the file specified by file_path. Shouldn’t you do sys.save(file_path, gamedata)?

@ashherb2u

local game_data= sys.load(“gamedata”)

I think this should be sys.load(file_path) just like @Gmanicus suggested.

[ashherb2u]

thanks guys