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    Json encode/decode problem?

    rrraptorrrraptor Member
    edited December 2020 in General questions
    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?
    SuperShape | Nice blured shapes with shadows | Simple button pad | Simple layer class | Simple UI library | 2D camera lib | Color picker | FPS graph | Dear ImGui | cute_c2
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    Comments

    • keszeghkeszegh Member
      yes, i think i had the same issue, those strings need to be converted manually to numbers.
      Longtitle Productions, creator of
      Fragmenter - animated loop machine and IKONOMIKON - the memory game
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    • MoKaLuxMoKaLux Member
      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.

      :/
      my growING GIDEROS github repositories: https://github.com/mokalux?tab=repositories
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    • rrraptorrrraptor Member
      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"
}
]]
      SuperShape | Nice blured shapes with shadows | Simple button pad | Simple layer class | Simple UI library | 2D camera lib | Color picker | FPS graph | Dear ImGui | cute_c2
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    • hgy29hgy29 Maintainer
      Accepted Answer
      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

      Likes: MoKaLux

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    • rrraptorrrraptor Member
      edited December 2020
      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 :blush:
      SuperShape | Nice blured shapes with shadows | Simple button pad | Simple layer class | Simple UI library | 2D camera lib | Color picker | FPS graph | Dear ImGui | cute_c2
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