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import { ICommonObject, IMessage, INode, INodeData, INodeParams } from '../../../src/Interface'
import { ConversationChain } from 'langchain/chains'
import { CustomChainHandler, getBaseClasses } from '../../../src/utils'
import { ChatPromptTemplate, HumanMessagePromptTemplate, MessagesPlaceholder, SystemMessagePromptTemplate } from 'langchain/prompts'
import { BufferMemory, ChatMessageHistory } from 'langchain/memory'
import { BaseChatModel } from 'langchain/chat_models/base'
import { AIChatMessage, HumanChatMessage } from 'langchain/schema'
const systemMessage = `The following is a friendly conversation between a human and an AI. The AI is talkative and provides lots of specific details from its context. If the AI does not know the answer to a question, it truthfully says it does not know.`
class ConversationChain_Chains implements INode {
label: string
name: string
type: string
icon: string
category: string
baseClasses: string[]
description: string
inputs: INodeParams[]
constructor() {
this.label = 'Conversation Chain'
this.name = 'conversationChain'
this.type = 'ConversationChain'
this.icon = 'chain.svg'
this.category = 'Chains'
this.description = 'Chat models specific conversational chain with memory'
this.baseClasses = [this.type, ...getBaseClasses(ConversationChain)]
this.inputs = [
{
label: 'Language Model',
name: 'model',
type: 'BaseChatModel'
},
{
label: 'Memory',
name: 'memory',
type: 'BaseMemory'
},
{
label: 'System Message',
name: 'systemMessagePrompt',
type: 'string',
rows: 4,
additionalParams: true,
optional: true,
placeholder: 'You are a helpful assistant that write codes'
}
]
}
async init(nodeData: INodeData): Promise<any> {
const model = nodeData.inputs?.model as BaseChatModel
const memory = nodeData.inputs?.memory as BufferMemory
const prompt = nodeData.inputs?.systemMessagePrompt as string
const obj: any = {
llm: model,
memory,
verbose: process.env.DEBUG === 'true' ? true : false
}
const chatPrompt = ChatPromptTemplate.fromPromptMessages([
SystemMessagePromptTemplate.fromTemplate(prompt ? `${prompt}\n${systemMessage}` : systemMessage),
new MessagesPlaceholder(memory.memoryKey ?? 'chat_history'),
HumanMessagePromptTemplate.fromTemplate('{input}')
])
obj.prompt = chatPrompt
const chain = new ConversationChain(obj)
return chain
}
async run(nodeData: INodeData, input: string, options: ICommonObject): Promise<string> {
const chain = nodeData.instance as ConversationChain
const memory = nodeData.inputs?.memory as BufferMemory
if (options && options.chatHistory) {
const chatHistory = []
const histories: IMessage[] = options.chatHistory
for (const message of histories) {
if (message.type === 'apiMessage') {
chatHistory.push(new AIChatMessage(message.message))
} else if (message.type === 'userMessage') {
chatHistory.push(new HumanChatMessage(message.message))
}
}
memory.chatHistory = new ChatMessageHistory(chatHistory)
chain.memory = memory
}
if (options.socketIO && options.socketIOClientId) {
const handler = new CustomChainHandler(options.socketIO, options.socketIOClientId)
const res = await chain.call({ input }, [handler])
return res?.response
} else {
const res = await chain.call({ input })
return res?.response
}
}
}
module.exports = { nodeClass: ConversationChain_Chains }
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