esx_core-esx-framework/client/main.lua

local guiEnabled = false
local myIdentity = {}
ESX = nil

Citizen.CreateThread(function()
	while ESX == nil do
		TriggerEvent('esx:getSharedObject', function(obj) ESX = obj end)
		Citizen.Wait(0)
	end
end)

function EnableGui(enable)
	SetNuiFocus(enable)
	guiEnabled = enable

	SendNUIMessage({
		type = "enableui",
		enable = enable
	})
end

RegisterNetEvent("esx_identity:showRegisterIdentity")
AddEventHandler("esx_identity:showRegisterIdentity", function()
	EnableGui(true)
end)

RegisterNUICallback('escape', function(data, cb)
	EnableGui(false)
end)

RegisterNUICallback('register', function(data, cb)
	local reason = ""
	myIdentity = data
	for theData, value in pairs(myIdentity) do
		if theData == "firstname" or theData == "lastname" then
			reason = verifyName(value)
			
			if reason ~= "" then
				break
			end
		elseif theData == "dateofbirth" then
			if value == "invalid" then
				reason = "Invalid date of birth!"
				break
			end
		elseif theData == "height" then
			local height = tonumber(value)
			if height then
				if height > 200 or height < 140 then
					reason = "Unacceptable player height!"
					break
				end
			else
				reason = "Unacceptable player height!"
				break
			end
		end
	end
	
	if reason == "" then
		--TriggerServerEvent('esx_identity:setIdentity', data)
		EnableGui(false)
		Citizen.Wait(500)
		--TriggerEvent('esx_skin:openSaveableMenu')
	else
		ESX.ShowNotification(reason)
	end
end)

Citizen.CreateThread(function()
	while true do
		if guiEnabled then
			DisableControlAction(0, 1, guiEnabled)        -- LookLeftRight
			DisableControlAction(0, 2, guiEnabled)        -- LookUpDown
			DisableControlAction(0, 142, guiEnabled)      -- MeleeAttackAlternate
			DisableControlAction(0, 106, guiEnabled)      -- VehicleMouseControlOverride
			if IsDisabledControlJustReleased(0, 142) then -- MeleeAttackAlternate
				SendNUIMessage({
					type = "click"
				})
			end
		end
		Citizen.Wait(10)
	end
end)

function verifyName(name)
	-- Don't allow short user names
	local nameLength = string.len(name)
	if nameLength > 25 or nameLength < 5 then
		return 'Your player name is either too short or too long.'
	end
	
	-- Don't allow special characters (doesn't always work)
	local count = 0
	for i in name:gmatch('[abcdefghijklmnopqrstuvwxyzåäöABCDEFGHIJKLMNOPQRSTUVWXYZÅÄÖ0123456789 -]') do
		count = count + 1
	end
	if count ~= nameLength then
		return 'Your player name contains special characters that are not allowed on this server.'
	end
	
	-- Does the player carry a first and last name?
	-- 
	-- Example:
	-- Allowed:     'Bob Joe'
	-- Not allowed: 'Bob'
	-- Not allowed: 'Bob joe'
	local spacesInName    = 0
	local spacesWithUpper = 0
	for word in string.gmatch(name, '%S+') do
	
		if string.match(word, '%u') then
			spacesWithUpper = spacesWithUpper + 1
		end
	
		spacesInName = spacesInName + 1
	end
	
	if spacesInName > 2 then
		return 'Your name contains more than two spaces'
	end
	
	if spacesWithUpper ~= spacesInName then
		return 'your name must start with a capital letter.'
	end
	
	return ''
end