Character Conversation API

The following piece of code is the most essential section to make a successful call to the Convai server to get a response in a conversation with a character.

Refer to Character API Doc for more details on the endpoint.

This portion of the code is present in the GlobalFunctions script in the Convai Roblox Integration Demo that you just tried out in the previous section.

The call is handled by the Chat_Character file present within the character model in the game Workspace.

function my_functions.callConvai(msg, sessionID, apiKey, charID)
	local httpSrv = game:GetService("HttpService")
	local baseUrl = "https://api.convai.com/character/getResponse"
	local gpt_response
	
	local function request()
		-- We restrict from making unnecessary calls if the following values are not set properly
		if apiKey == "" then
			print("Please provide a valid API Key")
			return
		end
		if charID == "" then
			print("Please enter a valid Character ID")
			return
		end
		
		-- REST API Cal
		local response = httpSrv:RequestAsync({
			Url = baseUrl,
			Method = "POST",
			Headers = {
				-- This is the most convenient way to send form-data in Roblox
				["Content-Type"] = "application/x-www-form-urlencoded",
				["CONVAI-API-KEY"] = apiKey
			},
			
			Body = string.format([[&userText=%s&sessionID=%s&charID=%s&voiceResponse=%s]], msg, sessionID, charID, 'False')
		})
		
		-- Inspect the response table
		if response.Success then
			print("Status code:", response.StatusCode, response.StatusMessage)
			print("Response body:\n", response.Body)
			local data = httpSrv:JSONDecode(response.Body)
			print("Response Text: ", data.text)
			print("Response Session ID: ", data.sessionID)
			gpt_response = response.Body --data.text
		else
			print("The request failed:", response.StatusCode, response.StatusMessage)
		end
	end

	-- Wrap the function in a 'pcall' to prevent the script from breaking if the request fails
	local success, message = pcall(request)
	--print("Status code: ", message)
	if gpt_response == nil then
		gpt_response = httpSrv:JSONEncode({sessionID = sessionID, text = "Sorry, I can't chat right now."})
	end
	return gpt_response
end

The above function is called in the chatbox implementation in the demo game. Here is an overview of what each part is doing:

function my_functions.callConvai(msg, sessionID, apiKey, charID)

The function accepts the message we get from the user. We send that along with the sessionID, and characterID. We also pass the API Key that we have set previously.

local httpSrv = game:GetService("HttpService")

HttpService allows HTTP requests to be sent from game servers. Details.

Now for the most important portion of the code:

-- REST API Cal
local response = httpSrv:RequestAsync({
	Url = baseUrl,
	Method = "POST",
	Headers = {
		-- This is the most convenient way to send form-data in Roblox
		["Content-Type"] = "application/x-www-form-urlencoded",
		["CONVAI-API-KEY"] = apiKey
	},
	
	Body = string.format([[&userText=%s&sessionID=%s&charID=%s&voiceResponse=%s]], msg, sessionID, charID, 'False')
}

Notice how Content-Type is set to "application/x-www-form-urlencoded". This is the only acceptable way to send form-data in Roblox. Since the endpoint only accepts form data, we had to parse the data in a suitable format to send it to the server.

While the Body of the request might look like a complicated string, it is actually quite simple. To break it down into its simple components, it can be viewed as:

{
    'userText': '<msg>',
    'sessionID': '<session-id>',
    'charID': '<character-id>',
    'voiceResponse': 'False'
}

The value for voiceResponse is set to False. Since we have no utility of the audio data that the server will generate, we just completely skip that audio generation. The reason is mentioned in the Constraints before.

The rest of the part is a simple response handling code. Since the response, we receive is JSON data, we have to decode that on the client side to read its content:

local data = httpSrv:JSONDecode(response.Body)
print("Response Text: ", data.text)
print("Response Session ID: ", data.sessionID)

That concludes our discussion on the /getResponse API.