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packages/@n8n/nodes-langchain/nodes/memory/MemoryPostgresChat/MemoryPostgresChat.node.ts

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+import { PostgresChatMessageHistory } from '@langchain/community/stores/message/postgres';
+import { BufferMemory, BufferWindowMemory } from '@langchain/classic/memory';
+import { configurePostgres } from 'n8n-nodes-base/dist/nodes/Postgres/transport/index';
+import type { PostgresNodeCredentials } from 'n8n-nodes-base/dist/nodes/Postgres/v2/helpers/interfaces';
+import { postgresConnectionTest } from 'n8n-nodes-base/dist/nodes/Postgres/v2/methods/credentialTest';
+import type {
+	ISupplyDataFunctions,
+	INodeType,
+	INodeTypeDescription,
+	SupplyData,
+} from 'n8n-workflow';
+import { NodeConnectionTypes } from 'n8n-workflow';
+import type pg from 'pg';
+
+import { getSessionId } from '@utils/helpers';
+import { logWrapper, getConnectionHintNoticeField } from '@n8n/ai-utilities';
+
+import {
+	sessionIdOption,
+	sessionKeyProperty,
+	contextWindowLengthProperty,
+	expressionSessionKeyProperty,
+} from '../descriptions';
+
+export class MemoryPostgresChat implements INodeType {
+	description: INodeTypeDescription = {
+		displayName: 'Postgres Chat Memory',
+		name: 'memoryPostgresChat',
+		icon: 'file:postgres.svg',
+		group: ['transform'],
+		version: [1, 1.1, 1.2, 1.3],
+		description: 'Stores the chat history in Postgres table.',
+		defaults: {
+			name: 'Postgres Chat Memory',
+		},
+		credentials: [
+			{
+				name: 'postgres',
+				required: true,
+				testedBy: 'postgresConnectionTest',
+			},
+		],
+		codex: {
+			categories: ['AI'],
+			subcategories: {
+				AI: ['Memory'],
+				Memory: ['Other memories'],
+			},
+			resources: {
+				primaryDocumentation: [
+					{
+						url: 'https://docs.n8n.io/integrations/builtin/cluster-nodes/sub-nodes/n8n-nodes-langchain.memorypostgreschat/',
+					},
+				],
+			},
+		},
+
+		inputs: [],
+
+		outputs: [NodeConnectionTypes.AiMemory],
+		outputNames: ['Memory'],
+		properties: [
+			getConnectionHintNoticeField([NodeConnectionTypes.AiAgent]),
+			sessionIdOption,
+			expressionSessionKeyProperty(1.2),
+			sessionKeyProperty,
+			{
+				displayName: 'Table Name',
+				name: 'tableName',
+				type: 'string',
+				default: 'n8n_chat_histories',
+				description:
+					'The table name to store the chat history in. If table does not exist, it will be created.',
+			},
+			{
+				...contextWindowLengthProperty,
+				displayOptions: { hide: { '@version': [{ _cnd: { lt: 1.1 } }] } },
+			},
+		],
+	};
+
+	methods = {
+		credentialTest: {
+			postgresConnectionTest,
+		},
+	};
+
+	async supplyData(this: ISupplyDataFunctions, itemIndex: number): Promise<SupplyData> {
+		const credentials = await this.getCredentials<PostgresNodeCredentials>('postgres');
+		const tableName = this.getNodeParameter('tableName', itemIndex, 'n8n_chat_histories') as string;
+		const sessionId = getSessionId(this, itemIndex);
+
+		const pgConf = await configurePostgres.call(this, credentials);
+		const pool = pgConf.db.$pool as unknown as pg.Pool;
+
+		const pgChatHistory = new PostgresChatMessageHistory({
+			pool,
+			sessionId,
+			tableName,
+		});
+
+		const memClass = this.getNode().typeVersion < 1.1 ? BufferMemory : BufferWindowMemory;
+		const kOptions =
+			this.getNode().typeVersion < 1.1
+				? {}
+				: { k: this.getNodeParameter('contextWindowLength', itemIndex) };
+
+		const memory = new memClass({
+			memoryKey: 'chat_history',
+			chatHistory: pgChatHistory,
+			returnMessages: true,
+			inputKey: 'input',
+			outputKey: 'output',
+			...kOptions,
+		});
+
+		return {
+			response: logWrapper(memory, this),
+		};
+	}
+}