Corona reading and writing files (first time access) - json

Question

I'm trying to write a function that will read sound and music states before starting my application.
The problem is: The first time it will run, there will be no data recorded.
First, I tried the suggested JSON function from here and I got this error:
Attempt to call global 'saveTable' (a nil value)
Is there a way to test if the file exists?
Then, I tried this one:
-- THIS function is just to try to find the file.
-- Load Configurations
function doesFileExist( fname, path )
local results = false
local filePath = system.pathForFile( fname, path )
--filePath will be 'nil' if file doesn,t exist and the path is "system.ResourceDirectory"
if ( filePath ) then
filePath = io.open( filePath, "r" )
end
if ( filePath ) then
print( "File found: " .. fname )
--clean up file handles
filePath:close()
results = true
else
print( "File does not exist: " .. fname )
end
return results
end
local fexist= doesFileExist("optionsTable.json","")
if (fexist == false) then
print (" optionsTable = nil")
optionsTable = {}
optionsTable.soundOn = true
optionsTable.musicOn = true
saveTable(optionsTable, "optionsTable.json") <<<--- ERROR HERE
print (" optionsTable Created")
end
The weird thing is that I'm getting an error at the saveTable(optionsTable,"optionsTable.json"). I just can't understand why.
If you have a working peace of code that handles the first time situation it will be enough to me. Thanks.

Answer 1

here's some code to check if the file exist you have to try and open the file first to know if it exist
function fileExists(fileName, base)
assert(fileName, "fileName is missing")
local base = base or system.ResourceDirectory
local filePath = system.pathForFile( fileName, base )
local exists = false
if (filePath) then -- file may exist wont know until you open it
local fileHandle = io.open( filePath, "r" )
if (fileHandle) then -- nil if no file found
exists = true
io.close(fileHandle)
end
end
return(exists)
end
and for usage
if fileExists("myGame.lua") then
-- do something wonderful
end
you can refer to this link for details