Save Table To File

Note: Originally this code is located at http://lua-users.org/wiki/SaveTableToFile This version changes 3 variables to local at function table.load to make it compatible with strict.lua. Thanks to nat12 for suggestion.

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Save a Table to a string or file; Load a Table from string or file Since building a string from a big table uses more time than saving the table to file and loading it from there, one should use table.save( table, true ) to get the stringtable from a big table

Characteristics:

• Userdata is not saved.
• Functions are saved via string.dump, so make sure it has no upvalues.
• References are saved.

NOTICE: NOT suitable for huge tables. Saving a table containing 100.000 subtables with 25 (1 short text line and 24 numerical entries) fields works. Somewhere above that performance is disastrous when saving. And you get an "constant table overflow" error when you try to read it back. With smaller tables it seems to work. Especially considering it is a cut and past solution to your need.

Testcode

function Main()
	 
dofile( "table.save-0.94.lua" )

print( "//Serialise Test ..." )
print( "//Building Table ..." )
	
local t = {}
t.a = 1
t.b = 2
t.c = {}
-- self reference
t.c.a = t
t.inass = { 1,2,3,4,5,6,7,8,9,10 }
t.inasst = { {1},{2},{3},{4},{5},{6},{7},{8},{9},{10} }
-- random
t.f = { [{ a = 5, b = 7, }] = "helloooooooo", [{ 1,2,3, m = 5, 5,6,7 }] = "A Table", }
t.func = function(x,y)
	print( "Hello\nWorld" )
	local sum = x+y
	return sum
end
-- get test string, not string.char(26)
local str = ""
for i = 0, 255 do
   --str = str.." "..i..": "..string.char( i )
   str = str..string.char( i )
end
t.lstri = { [str] = 1 }
t.lstrv = str

	
print( "\n## BEFORE SAVE ##" )

printtbl( t )

--// test save to file
assert( table.save( t, "test.tbl" ) == 1 )
	
--// test save to string
local strtbl = table.save( t )

--// test save to string over file
local strtbl2 = table.save( t, true )
	
-- load table from file
local t2 = table.load( "test.tbl" )

-- load table from string 1	
local t3 = table.load( strtbl )

-- load table from string 2
local t4 = table.load( strtbl2 )

print( "\n## AFTER SAVE ##" )

print( "\n## LOAD FROM FILE ##" )
printtbl( t2 )

print( "\n## LOAD FROM STRING ##" )
--printtbl( t3 )

print( "\n## LOAD FROM STRING OVER FILE ##" )
--printtbl( t4 )

print( "\n//Test References" )
	
assert( t2.c.a == t2 )
assert( t3.c.a == t3 )
assert( t4.c.a == t4 )
	
print( "\n//Test Long string" )

assert( t.lstrv == t2.lstrv )
assert( t.lstrv == t3.lstrv )
assert( t.lstrv == t4.lstrv )

print( "\n//Test Function\n\n" )

assert( t2.func(2,2) == 4 )
assert( t3.func(2,3) == 5 )
assert( t4.func(2,3) == 5 )

print( "\n*** Test SUCSESSFULL ***" )

end

function printtbl( t,tab,lookup )
	local lookup = lookup or { [t] = 1 }
	local tab = tab or ""
	for i,v in pairs( t ) do
		print( tab..tostring(i), v )
		if type(i) == "table" and not lookup[i] then
			lookup[i] = 1
			print( tab.."Table: i" )
			printtbl( i,tab.."\t",lookup )
		end
		if type(v) == "table" and not lookup[v] then
			lookup[v] = 1
			print( tab.."Table: v" )
			printtbl( v,tab.."\t",lookup )
		end
	end
end

Main()