Roblox- how to store large arrays in roblox datastores

Question

i am trying to make a game where players create their own buildings and can then save them for other players to see and play on. However, roblox doesn't let me store all the data needed for the whole creation(there are several properties for each brick) All i get is this error code: 104: Cannot store Array in DataStore

any help would be greatly appreciated!

Answer 1

I suggest what @Crabway said, use HttpService.

local httpService = game:GetService("HttpService")
print(httpService:JSONEncode({a = "b", b = "c"}) -- {"a":"b","b":"c"}

But if you have any UserData values such as Vector3s, CFrames, Color3s, BrickColors and Enum items, then use this library by Defaultio. It's actually pretty nice.

local library = require(workspace:WaitForChild("JSONWithUserdata"))
library:Encode({Vector3.new(0, 0, 0)})

If you want a little documentation, then look at the first comment in the script:

-- Defaultio

--[[

    This module adds support for encoding userdata values to JSON strings.
    It also supports lists which skip indices, such as {[1] = "a", [2] = "b", [4] = "c"}

    Userdata support is implemented by replacing userdata types with a new table, with keys _T and _V:
        _T = userdata type enum (index in the supportedUserdataTypes list)
        _V = a value or table representing the value

    Follow the examples bellow to add suppport for additional userdata types.

    ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 

    Usage example:

        local myTable = {CFrame.new(), BrickColor.Random(), 4, "String", Enum.Material.CorrodedMetal}

        local jsonModule = require(PATH_TO_MODULE)

        local jsonString = jsonModule:Encode(myTable)

        local decodedTable = jsonModule:Decode(jsonString)

--]]

Answer 2

Crabway's answer is correct in that the HttpService's JSONEncode and JSONDecode methods are the way to go about tackling this problem. As it says on the developer reference page for the DataStoreService, Data is ... saved as a string in data stores, regardless of its initial type. (https://developer.roblox.com/articles/Datastore-Errors.) This explains the error you received, as you cannot simply push a table to the data store; instead, you must first encode a table's data into a string using JSONEncode.

While I agree with much of Crabway's answer, I believe the function createBrick would not behave as intended. Consider the following trivial example:

httpService = game:GetService("HttpService")
t = {
    hello = 1,
    goodbye = 2
}

s = httpService:JSONEncode(t)
print(s)
> {"goodbye":2,"hello":1}

u = httpService:JSONDecode(s)
for k, v in pairs(u) do print(k, v) end
> hello 1
> goodbye 2

As you can see, the table returned by JSONDecode, like the original, uses strings as keys rather than numeric indices. Therefore, createBrick should be written something like this:

function createBrick(t)
    local brick = Instance.new("Part")
    brick.Size = t.Size
    brick.Position = t.Position
    brick.BrickColor = t.BrickColor
    brick.Material = t.Material
    -- FIXME: set any other necessary properties.
    -- NOTE: try to set parent last for optimization reasons.
    brick.Parent = t.Parent
    return brick
end

As for encoding a model, calling GetChildren would produce a table of the model's children, which you could then loop through and encode the properties of everything within. Note that in Crabway's answer, he only accounts for Parts and WedgeParts. You should account for all parts using object:IsA("BasePart") and also check for unions with object:IsA("UnionOperation"). The following is a very basic example in which I do not store the encoded data; rather, I am just trying to show how to check the necessary cases.

function encodeModel(model)
    local children = model:GetChildren()
    for _, child in ipairs(children) do
        if ((child:IsA("BasePart")) or (child:IsA("UnionOperation"))) then
            -- FIXME: encode child
        else if (child:IsA("Model")) then
            -- FIXME: using recursion, loop through the sub-model's children.
        end
    end
    return
end

For userdata, such as Vector3s or BrickColors, you will probably want to convert those to strings when you go to encode them with JSONEncode.

-- Example: part with "Brick red" BrickColor.
color = tostring(part.BrickColor)
print(string.format("%q", color))
> "Bright red"

Answer 3

I'm not sure if this is the best method, but it's my attempt. Below is an example of a table, you can use tables to store several values. I think you can use HttpService's JSONEncode function to convert tables into strings (which hopefully can be saved more efficiently)

JSONEncode (putting brick's data into a string, which you can save into the DataStore

local HttpService = game:GetService("HttpService")

-- this is an example of what we'll convert into a json string
local exampleBrick = {
    ["Size"] = Vector3.new(3,3,3),
    ["Position"] = Vector3.new(0,1.5,0),
    ["BrickColor"] = BrickColor.new("White")
    ["Material"] = "Concrete"
}

local brickJSON = HttpService:JSONEncode(exampleBrick)
print(brickJSON)

-- when printed, you'll get something like
-- { "Size": Vector3.new(3,3,3), "Position": Vector3.new(0,1.5,0), "BrickColor": BrickColor.new("White"), "Material": "Concrete"}
-- if you want to refer to this string in a script, surround it with two square brackets ([[) e.g. [[{"Size": Vector3.new(3,3,3)... }]]

JSONDecode (reading the string and converting it back into a brick)

local HttpService = game:GetService("HttpService")
local brickJSON = [[ {"Size": Vector3.new(3,3,3), "Position": Vector3.new(0,1.5,0), "BrickColor": BrickColor.new("White"), "Material": "Concrete"} ]]

function createBrick(tab)
    local brick = Instance.new("Part")
    brick.Parent = <insert parent here>
    brick.Size = tab[1]
    brick.Position= tab[2]
    brick.BrickColor= tab[3]
    brick.Material= tab[4]
end

local brickData = HttpService:JSONDecode(brickJSON)
createBrick(brickData) --this line actually spawns the brick

The function can also be wrapped in a pcall if you want to account for any possible datastore errors.

Encoding a whole model into a string

Say your player's 'building' is a model, you can use the above encode script to convert all parts inside a model into a json string to save.

local HttpService = game:GetService("HttpService")
local StuffWeWantToSave = {}

function getPartData(part)
    return( {part.Size,part.Position,part.BrickColor,part.Material} )
end

local model = workspace.Building --change this to what the model is
local modelTable = model:Descendants()
for i,v in pairs(modelTable) do
    if v:IsA("Part") or v:IsA("WedgePart") then
        table.insert(StuffWeWantToSave, HttpService:JSONEncode(getPartData(modelTable[v])))
    end
end

Decoding a string into a whole model

This will probably occur when the server is loading a player's data.

local HttpService = game:GetService("HttpService")
local SavedStuff = game:GetService("DataStoreService"):GetDataStore("blabla") --I don't know how you save your data, so you'll need to adjust this and the rest of the scripts (as long as you've saved the string somewhere in the player's DataStore)

function createBrick(tab)
    local brick = Instance.new("Part")
    brick.Parent = <insert parent here>
    brick.Size = tab[1]
    brick.Position= tab[2]
    brick.BrickColor= tab[3]
    brick.Material= tab[4]
end

local model = Instance.new("Model") --if you already have 'bases' for the players to load their stuff in, remove this instance.new
model.Parent = workspace

for i,v in pairs(SavedStuff) do
    if v[1] ~= nil then
        CreateBrick(v)
    end
end

FilteringEnabled

If your game uses filteringenabled, make sure that only the server handles saving and loading data!! (you probably already knew that) If you want the player to save by clicking a gui button, make the gui button fire a RemoteFunction that sends their base's data to the server to convert it to a string.

BTW I'm not that good at scripting so I've probably made a mistake somehwere.. good luck though