feat(Postgres Chat Memory, Redis Chat Memory, Xata): Add support for context window length

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

@@ -10,7 +10,7 @@ import type { BufferWindowMemoryInput } from 'langchain/memory';
 import { BufferWindowMemory } from 'langchain/memory';
 import { logWrapper } from '../../../utils/logWrapper';
 import { getConnectionHintNoticeField } from '../../../utils/sharedFields';
-import { sessionIdOption, sessionKeyProperty } from '../descriptions';
+import { sessionIdOption, sessionKeyProperty, contextWindowLengthProperty } from '../descriptions';
 import { getSessionId } from '../../../utils/helpers';
 
 class MemoryChatBufferSingleton {
@@ -130,13 +130,7 @@ export class MemoryBufferWindow implements INodeType {
 				},
 			},
 			sessionKeyProperty,
-			{
-				displayName: 'Context Window Length',
-				name: 'contextWindowLength',
-				type: 'number',
-				default: 5,
-				description: 'The number of previous messages to consider for context',
-			},
+			contextWindowLengthProperty,
 		],
 	};
 

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

@@ -1,15 +1,15 @@
 /* eslint-disable n8n-nodes-base/node-dirname-against-convention */
 import type { IExecuteFunctions, INodeType, INodeTypeDescription, SupplyData } from 'n8n-workflow';
 import { NodeConnectionType } from 'n8n-workflow';
-import { BufferMemory } from 'langchain/memory';
+import { BufferMemory, BufferWindowMemory } from 'langchain/memory';
 import { PostgresChatMessageHistory } from '@langchain/community/stores/message/postgres';
 import type pg from 'pg';
 import { configurePostgres } from 'n8n-nodes-base/dist/nodes/Postgres/v2/transport';
 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 { logWrapper } from '../../../utils/logWrapper';
 import { getConnectionHintNoticeField } from '../../../utils/sharedFields';
-import { sessionIdOption, sessionKeyProperty } from '../descriptions';
+import { sessionIdOption, sessionKeyProperty, contextWindowLengthProperty } from '../descriptions';
 import { getSessionId } from '../../../utils/helpers';
 
 export class MemoryPostgresChat implements INodeType {
@@ -18,7 +18,7 @@ export class MemoryPostgresChat implements INodeType {
 		name: 'memoryPostgresChat',
 		icon: 'file:postgres.svg',
 		group: ['transform'],
-		version: [1],
+		version: [1, 1.1],
 		description: 'Stores the chat history in Postgres table.',
 		defaults: {
 			name: 'Postgres Chat Memory',
@@ -60,6 +60,10 @@ export class MemoryPostgresChat implements INodeType {
 				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 } }] } },
+			},
 		],
 	};
 
@@ -83,12 +87,19 @@ export class MemoryPostgresChat implements INodeType {
 			tableName,
 		});
 
-		const memory = new BufferMemory({
+		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,
 		});
 
 		async function closeFunction() {

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

@@ -7,14 +7,14 @@ import {
 	type SupplyData,
 	NodeConnectionType,
 } from 'n8n-workflow';
-import { BufferMemory } from 'langchain/memory';
+import { BufferMemory, BufferWindowMemory } from 'langchain/memory';
 import type { RedisChatMessageHistoryInput } from '@langchain/redis';
 import { RedisChatMessageHistory } from '@langchain/redis';
 import type { RedisClientOptions } from 'redis';
 import { createClient } from 'redis';
 import { logWrapper } from '../../../utils/logWrapper';
 import { getConnectionHintNoticeField } from '../../../utils/sharedFields';
-import { sessionIdOption, sessionKeyProperty } from '../descriptions';
+import { sessionIdOption, sessionKeyProperty, contextWindowLengthProperty } from '../descriptions';
 import { getSessionId } from '../../../utils/helpers';
 
 export class MemoryRedisChat implements INodeType {
@@ -23,7 +23,7 @@ export class MemoryRedisChat implements INodeType {
 		name: 'memoryRedisChat',
 		icon: 'file:redis.svg',
 		group: ['transform'],
-		version: [1, 1.1, 1.2],
+		version: [1, 1.1, 1.2, 1.3],
 		description: 'Stores the chat history in Redis.',
 		defaults: {
 			name: 'Redis Chat Memory',
@@ -95,6 +95,10 @@ export class MemoryRedisChat implements INodeType {
 				description:
 					'For how long the session should be stored in seconds. If set to 0 it will not expire.',
 			},
+			{
+				...contextWindowLengthProperty,
+				displayOptions: { hide: { '@version': [{ _cnd: { lt: 1.3 } }] } },
+			},
 		],
 	};
 
@@ -143,12 +147,19 @@ export class MemoryRedisChat implements INodeType {
 		}
 		const redisChatHistory = new RedisChatMessageHistory(redisChatConfig);
 
-		const memory = new BufferMemory({
+		const memClass = this.getNode().typeVersion < 1.3 ? BufferMemory : BufferWindowMemory;
+		const kOptions =
+			this.getNode().typeVersion < 1.3
+				? {}
+				: { k: this.getNodeParameter('contextWindowLength', itemIndex) };
+
+		const memory = new memClass({
 			memoryKey: 'chat_history',
 			chatHistory: redisChatHistory,
 			returnMessages: true,
 			inputKey: 'input',
 			outputKey: 'output',
+			...kOptions,
 		});
 
 		async function closeFunction() {

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

@@ -2,11 +2,11 @@
 import { NodeConnectionType, NodeOperationError } from 'n8n-workflow';
 import type { IExecuteFunctions, INodeType, INodeTypeDescription, SupplyData } from 'n8n-workflow';
 import { XataChatMessageHistory } from '@langchain/community/stores/message/xata';
-import { BufferMemory } from 'langchain/memory';
+import { BufferMemory, BufferWindowMemory } from 'langchain/memory';
 import { BaseClient } from '@xata.io/client';
 import { logWrapper } from '../../../utils/logWrapper';
 import { getConnectionHintNoticeField } from '../../../utils/sharedFields';
-import { sessionIdOption, sessionKeyProperty } from '../descriptions';
+import { sessionIdOption, sessionKeyProperty, contextWindowLengthProperty } from '../descriptions';
 import { getSessionId } from '../../../utils/helpers';
 
 export class MemoryXata implements INodeType {
@@ -15,7 +15,7 @@ export class MemoryXata implements INodeType {
 		name: 'memoryXata',
 		icon: 'file:xata.svg',
 		group: ['transform'],
-		version: [1, 1.1, 1.2],
+		version: [1, 1.1, 1.2, 1.3],
 		description: 'Use Xata Memory',
 		defaults: {
 			name: 'Xata',
@@ -81,6 +81,10 @@ export class MemoryXata implements INodeType {
 				},
 			},
 			sessionKeyProperty,
+			{
+				...contextWindowLengthProperty,
+				displayOptions: { hide: { '@version': [{ _cnd: { lt: 1.3 } }] } },
+			},
 		],
 	};
 
@@ -120,12 +124,19 @@ export class MemoryXata implements INodeType {
 			apiKey: credentials.apiKey as string,
 		});
 
-		const memory = new BufferMemory({
+		const memClass = this.getNode().typeVersion < 1.3 ? BufferMemory : BufferWindowMemory;
+		const kOptions =
+			this.getNode().typeVersion < 1.3
+				? {}
+				: { k: this.getNodeParameter('contextWindowLength', itemIndex) };
+
+		const memory = new memClass({
 			chatHistory,
 			memoryKey: 'chat_history',
 			returnMessages: true,
 			inputKey: 'input',
 			outputKey: 'output',
+			...kOptions,
 		});
 
 		return {

packages/@n8n/nodes-langchain/nodes/memory/descriptions.ts

@@ -33,3 +33,11 @@ export const sessionKeyProperty: INodeProperties = {
 		},
 	},
 };
+
+export const contextWindowLengthProperty: INodeProperties = {
+	displayName: 'Context Window Length',
+	name: 'contextWindowLength',
+	type: 'number',
+	default: 5,
+	hint: 'How many past interactions the model receives as context',
+};