Help with getting an template id

how do i get an template id from an id with a script

You have to elaborate with what you want to achieve
If you want to add an id to something like a decal you can do this

Decal.Texture = "rbxassetid://".. TextureIdGoesHere

I assume you’re trying to convert a catalog id to an asset id, if so then the following reply is what you’re looking for:

However, you must change 2 things:

  1. assetId-i instead of assetId+i
  2. return sameCreator instead of return isDecal and sameCreator

If you just want to display the image in-game without fetching the id then you can use the thumbnail endpoint as shown here:

Where userInput is your decal/catalog id

but @lazerwolf11 and @NyrionDev look for a sec in the code and tell me how is it possible to get the template id

game.ReplicatedStorage.Shirts.OnClientEvent:Connect(function(shirts)
	for i, v in pairs(shirts) do
		local marketplace = game:GetService("MarketplaceService")
		local ImageId = "rbxthumb://type=Asset&id=" .. v.Id .. "&w=420&h=420"
		local namestring = script.Temp:WaitForChild("name")
		local imageidstring = script.Temp:WaitForChild("imageid")
		local Cost = v.Price
		local nameofshirt = v.Name -- Fixed variable name
		local shirt = game.Workspace.STORE.shirts.shirt1["Uniform Giver"].Coathanger:WaitForChild("Shirt")


		imageidstring = ImageId
		namestring = nameofshirt

		local Temp = script.Temp:Clone()
		Temp.Parent = script.Parent
		Temp.Shirt.Image = ImageId
		Temp.name.Text = nameofshirt -- Fixed property name
		Temp.Price.Text = Cost .. " robux"
		Temp.Name = v.Id

		Temp.Shirt.MouseButton1Click:Connect(function()
			--when you click on the shirt it will display it on a 3d model
			shirt.ShirtTemplate = "rbxassetid://" .. v.Id
		end)
	end
end)