n8n/packages/@n8n/nodes-langchain/nodes/chains/ChainRetrievalQA/ChainRetrievalQa.node.ts

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import {
NodeConnectionType,
type IExecuteFunctions,
type INodeExecutionData,
type INodeType,
type INodeTypeDescription,
NodeOperationError,
} from 'n8n-workflow';
import { RetrievalQAChain } from 'langchain/chains';
import type { BaseLanguageModel } from '@langchain/core/language_models/base';
import type { BaseRetriever } from '@langchain/core/retrievers';
import { getTemplateNoticeField } from '../../../utils/sharedFields';
import { getPromptInputByType } from '../../../utils/helpers';
import { getTracingConfig } from '../../../utils/tracing';
export class ChainRetrievalQa implements INodeType {
description: INodeTypeDescription = {
displayName: 'Question and Answer Chain',
name: 'chainRetrievalQa',
icon: 'fa:link',
group: ['transform'],
version: [1, 1.1, 1.2, 1.3],
description: 'Answer questions about retrieved documents',
defaults: {
name: 'Question and Answer Chain',
color: '#909298',
},
codex: {
alias: ['LangChain'],
categories: ['AI'],
subcategories: {
AI: ['Chains', 'Root Nodes'],
},
resources: {
primaryDocumentation: [
{
url: 'https://docs.n8n.io/integrations/builtin/cluster-nodes/root-nodes/n8n-nodes-langchain.chainretrievalqa/',
},
],
},
},
// eslint-disable-next-line n8n-nodes-base/node-class-description-inputs-wrong-regular-node
inputs: [
NodeConnectionType.Main,
{
displayName: 'Model',
maxConnections: 1,
type: NodeConnectionType.AiLanguageModel,
required: true,
},
{
displayName: 'Retriever',
maxConnections: 1,
type: NodeConnectionType.AiRetriever,
required: true,
},
],
outputs: [NodeConnectionType.Main],
credentials: [],
properties: [
getTemplateNoticeField(1960),
{
displayName: 'Query',
name: 'query',
type: 'string',
required: true,
default: '={{ $json.input }}',
displayOptions: {
show: {
'@version': [1],
},
},
},
{
displayName: 'Query',
name: 'query',
type: 'string',
required: true,
default: '={{ $json.chat_input }}',
displayOptions: {
show: {
'@version': [1.1],
},
},
},
{
displayName: 'Query',
name: 'query',
type: 'string',
required: true,
default: '={{ $json.chatInput }}',
displayOptions: {
show: {
'@version': [1.2],
},
},
},
{
displayName: 'Prompt',
name: 'promptType',
type: 'options',
options: [
{
// eslint-disable-next-line n8n-nodes-base/node-param-display-name-miscased
name: 'Take from previous node automatically',
value: 'auto',
description: 'Looks for an input field called chatInput',
},
{
// eslint-disable-next-line n8n-nodes-base/node-param-display-name-miscased
name: 'Define below',
value: 'define',
description:
'Use an expression to reference data in previous nodes or enter static text',
},
],
displayOptions: {
hide: {
'@version': [{ _cnd: { lte: 1.2 } }],
},
},
default: 'auto',
},
{
displayName: 'Text',
name: 'text',
type: 'string',
required: true,
default: '',
typeOptions: {
rows: 2,
},
displayOptions: {
show: {
promptType: ['define'],
},
},
},
],
};
async execute(this: IExecuteFunctions): Promise<INodeExecutionData[][]> {
this.logger.verbose('Executing Retrieval QA Chain');
const model = (await this.getInputConnectionData(
NodeConnectionType.AiLanguageModel,
0,
)) as BaseLanguageModel;
const retriever = (await this.getInputConnectionData(
NodeConnectionType.AiRetriever,
0,
)) as BaseRetriever;
const items = this.getInputData();
const chain = RetrievalQAChain.fromLLM(model, retriever);
const returnData: INodeExecutionData[] = [];
// Run for each item
for (let itemIndex = 0; itemIndex < items.length; itemIndex++) {
try {
let query;
if (this.getNode().typeVersion <= 1.2) {
query = this.getNodeParameter('query', itemIndex) as string;
} else {
query = getPromptInputByType({
ctx: this,
i: itemIndex,
inputKey: 'text',
promptTypeKey: 'promptType',
});
}
if (query === undefined) {
throw new NodeOperationError(this.getNode(), 'The query parameter is empty.');
}
const response = await chain.withConfig(getTracingConfig(this)).invoke({ query });
returnData.push({ json: { response } });
} catch (error) {
if (this.continueOnFail()) {
returnData.push({ json: { error: error.message }, pairedItem: { item: itemIndex } });
continue;
}
throw error;
}
}
return [returnData];
}
}