Json encode/decode problem?

rrraptor

I have a problem with saving and loading data. The problem is when I print my table using inspect lib Im getting this:

{ { { result = 1 }, { result = 1 } }, { { 3.0525409300258, -7.1188186867317, bias = -8.3549980727365e-005, delta = -0.00027849993575788, result = 0.016855024522915 }, { 2.4140298299185, -0.60132939530735, bias = 0.00033360795785989, delta = 0.0011120265261996, result = 0.85955375972833 }, { -5.7339817836074, -5.5835565614512, bias = 1.2580778860342e-007, delta = 4.1935929534474e-007, result = 1.2157334382094e-005 }, { -7.021765927752, 2.6025379863218, bias = -4.3028971089474e-005, delta = -0.00014342990363158, result = 0.011903162333153 } }, { { 6.5062302538448, -3.5666890973304, -13.35381471873, 4.7209472334399, bias = -0.00077494182403473, delta = -0.0025831394134491, result = 0.052205570616817 } } }

It looks absolutely OK. Then I use json to encode this table to a string like that:

local str = json.encode(data)

And Im getting this:

[[{"result":1},{"result":1}],[{"1":3.0525409300258,"2":-7.1188186867317,"bias":-8.3549980727365e-005,"result":0.016855024522915,"delta":-0.00027849993575788},{"1":2.4140298299185,"2":-0.60132939530735,"bias":0.00033360795785989,"result":0.85955375972833,"delta":0.0011120265261996},{"1":-5.7339817836074,"2":-5.5835565614512,"bias":1.2580778860342e-007,"result":1.2157334382094e-005,"delta":4.1935929534474e-007},{"1":-7.021765927752,"2":2.6025379863218,"bias":-4.3028971089474e-005,"result":0.011903162333153,"delta":-0.00014342990363158}],[{"1":6.5062302538448,"2":-3.5666890973304,"3":-13.35381471873,"4":4.7209472334399,"bias":-0.00077494182403473,"result":0.052205570616817,"delta":-0.0025831394134491}]]

Looks OK again.

The fun part is when I load data from string using

local tmp = json.decode(myStrData)

and print tmp table with inspect, Im getting this:

{ { { result = 1 }, { result = 1 } }, { { ["1"] = -6.7174306784856, ["2"] = 3.2358287613015, bias = -7.191155644351e-005, delta = -0.00023970518814503, result = 0.02984773214605 }, { ["1"] = -1.1534704652545, ["2"] = 2.8737936954513, bias = 0.00018268117948989, delta = 0.00060893726496631, result = 0.84811175708117 }, { ["1"] = 2.6744957060553, ["2"] = -5.9305356187969, bias = -5.5072801877998e-005, delta = -0.00018357600625999, result = 0.037114576551705 }, { ["1"] = -5.4239175469685, ["2"] = -5.5179995861126, bias = 8.1621380532062e-008, delta = 2.7207126844021e-007, result = 1.7699783810485e-005 } }, { { ["1"] = 7.8235855177385, ["2"] = -4.4678815169207, ["3"] = 4.8548510429201, ["4"] = -14.527891065454, bias = -0.00031742496963396, delta = -0.0010580832321132, result = 0.033079933620093 } } }

As you can see number keys became string keys. What can I do about it?

keszegh

yes, i think i had the same issue, those strings need to be converted manually to numbers.

MoKaLux

from the github:
Gotchas / Warnings

This method is not appropriate for saving/restoring tables. It is meant to be used by the programmer mainly while debugging a program.

rrraptor

Well, it kinda works, but only if table containts only number keys.
So this works OK:

local inspect = require "Libs/inspect" require "json"   local t = {2, 4, 6} print("inspected:", inspect(t)) local str = json.encode(t) print("encoded", str) print("decoding...") local tmp = json.decode(str) print("inspected:", inspect(tmp)) --[[ output:   inspected: { 2, 4, 6 } encoded [2,4,6] decoding... inspected: { 2, 4, 6 } --]]

And with this:

local t = {2, 4, 6, key = "value"}

--[[ inspected: { 2, 4, 6, key = "value" } encoded {"1":2,"2":4,"3":6,"key":"value"} decoding... inspected: { ["1"] = 2, ["2"] = 4, ["3"] = 6, key = "value" } ]]

hgy29

JSON tables have strings only as keys, while JSON arrays have implicit numerical keys. Encoder does its best to map lua tables to json, but it can’t handle all kind of lua tables

rrraptor

hgy29 said:

JSON tables have strings only as keys, while JSON arrays have implicit numerical keys. Encoder does its best to map lua tables to json, but it can’t handle all kind of lua tables

Well, its ok, I can change structure a bit

-- works perfectly { weights = {6.5062302538448, -3.5666890973304, -13.35381471873, 4.7209472334399}, bias = -0.00077494182403473, delta = -0.0025831394134491, result = 0.052205570616817 }

Its even more readable now