Roblox Studio - how do I run a script right before game starts? - plugins

Question

I'm attempting to create a plugin that fetches additional code from a server before the user plays the game on roblox studio.
Basically, the user will use something like blockly to create luau code on a website and I want to sent that code to roblox studio. I've seen some plugins that fetch new data from a server from time to time and I've been able to do that, but I'd like to see if there's a way to only fetch the new code when the user clicks the play button because it could be expensive to request new data every 5 seconds or so.
Below is a simple plugin that attempts to send a request to the server when the game loads, but the script never goes beyond game.Loaded:Wait()
Main file:
local Request = require(script.Parent.Request)
local URL = "http://localhost:3333"
local toolbar = plugin:CreateToolbar("Test")
local button = toolbar:CreateButton("Test", "Test", "rbxassetid://4458901886")
local isListening = false
local request = Request.new()
local ok
local json
local function onClick ()
isListening = not isListening
if (isListening == false) then
return print("Not listening")
end
print("Listening")
if not game:IsLoaded() then
print(game.Loaded)
game.Loaded:Wait()
print("Game has started")
ok, json = request:Get(URL)
print(ok, json)
end
end
button.Click:Connect(onClick)
Request file:
local Request = {}
Request.__index = Request
function Request.new()
return setmetatable({}, Request)
end
function Request:Get(URL)
local ok, result = pcall(game.HttpService.GetAsync, game.HttpService, URL)
local json = game.HttpService:JSONDecode(result)
return ok, json
end
return Request

Answer 1

There isn't an explicit signal to detect when a game is about to start.
But, whenever you hit the Play button, the Edit session ends and the Play session begins. When a session ends, all of the plugins are unloaded. So you could use the plugin.Unloading signal to detect when the Edit session is ending, but it will also fire when the user closes the place, when you stop play testing, or when the plugin is disabled or uninstalled.
You could combine that signal with the RunService:IsEdit() function so that the behavior only triggers when exiting Edit mode, but this is still a really hazy signal.
So in a Script in your plugin, you could do something like this :
local RunService = game:GetService("RunService")
local Request = require(script.Parent.Request)
local URL = "<YOUR URL>"
-- listen for when sessions end
plugin.Unloading:Connect(function()
-- disregard sessions that aren't Edit Mode
if not RunService:IsEdit() end
return
end
print("Game about to start... maybe. The game might also be closing, or the plugin might be disabled from the PluginManager.")
local ok, json = request:Get(URL)
print(ok, json)
end)
Debugging this may be difficult as the Output console is cleared any time you start a Play session, so you won't see any of your print statements. But if you close the place, your logs will be preserved on the Welcome Screen. Just go View > Output to open the Output window.