Merge pull request #12 from upstash/DX-1003

feat: allow offsetting chat history

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@upstash/rag-chat",
-  "version": "0.0.34-alpha",
+  "version": "0.0.35-alpha",
   "main": "./dist/index.js",
   "module": "./dist/index.mjs",
   "types": "./dist/index.d.ts",

src/history/in-memory-custom-history.test.ts

@@ -34,3 +34,28 @@ test("should give all the messages", async () => {
   const final = (await history.getMessages()).map((message) => message.content as string);
   expect(["Hello!", "Hello, human.", "Whats your name?", "Upstash", "Good."]).toEqual(final);
 });
+
+test("should give all the messages with offset pagination", async () => {
+  const history = new CustomInMemoryChatMessageHistory({
+    messages: [],
+    metadata: { helloWorld: "hey" },
+  });
+  await history.addUserMessage("Hello!");
+  await history.addAIMessage("Hello, human.");
+  await history.addUserMessage("Whats your name?");
+  await history.addAIMessage("Upstash");
+  await history.addUserMessage("Good. How are you?");
+  await history.addAIMessage("I'm good. Thanks.");
+
+  // eslint-disable-next-line unicorn/no-await-expression-member
+  let final = (await history.getMessages({ offset: 0, length: 2 })).map(
+    (message) => message.content as string
+  );
+  expect(["Upstash", "Good. How are you?", "I'm good. Thanks."]).toEqual(final);
+
+  // eslint-disable-next-line unicorn/no-await-expression-member
+  final = (await history.getMessages({ offset: 2, length: 3 })).map(
+    (message) => message.content as string
+  );
+  expect(["Hello!", "Hello, human.", "Whats your name?", "Upstash"]).toEqual(final);
+});

src/history/in-memory-custom-history.ts

@@ -29,10 +29,21 @@ export class CustomInMemoryChatMessageHistory extends BaseListChatMessageHistory
    * instance.
    * @returns Array of stored BaseMessage instances.
    */
-  async getMessages(): Promise<BaseMessage[]> {
-    return this.topLevelChatHistoryLength
-      ? this.messages.slice(1).slice(-this.topLevelChatHistoryLength)
-      : this.messages;
+  async getMessages(options?: { offset?: number; length?: number }): Promise<BaseMessage[]> {
+    if (options) {
+      const start = options.offset ?? 0;
+      const length = options.length ?? 0;
+      const end = start + length + 1;
+
+      const reversedMessages = [...this.messages].reverse();
+      const slicedMessages = reversedMessages.slice(start, end);
+
+      return slicedMessages.reverse(); // Reverse back to original order
+    } else if (this.topLevelChatHistoryLength) {
+      return this.messages.slice(1).slice(-this.topLevelChatHistoryLength);
+    } else {
+      return this.messages;
+    }
   }
 
   /**

src/history/redis-custom-history.test.ts

@@ -0,0 +1,30 @@
+import { Redis } from "@upstash/redis";
+import { afterAll, describe, expect, test } from "bun:test";
+import { CustomUpstashRedisChatMessageHistory } from "./redis-custom-history";
+
+describe("Redis chat-history", () => {
+  const redis = Redis.fromEnv();
+  afterAll(async () => {
+    await redis.flushdb();
+  });
+
+  test("should give last 3 messages from redis", async () => {
+    const history = new CustomUpstashRedisChatMessageHistory({
+      client: redis,
+      metadata: { helloWorld: "hey" },
+      sessionId: "testing-features",
+    });
+    await history.addUserMessage("Hello!");
+    await history.addAIMessage("Hello, human.");
+    await history.addUserMessage("Whats your name?");
+    await history.addAIMessage("Upstash");
+    await history.addUserMessage("Good. How are you?");
+    await history.addAIMessage("I'm good. Thanks.");
+
+    // eslint-disable-next-line unicorn/no-await-expression-member
+    const final = (await history.getMessages({ offset: 0, length: 2 })).map(
+      (message) => message.content as string
+    );
+    expect(["Upstash", "Good. How are you?", "I'm good. Thanks."]).toEqual(final);
+  });
+});

src/history/redis-custom-history.ts

@@ -67,13 +67,15 @@ export class CustomUpstashRedisChatMessageHistory extends BaseListChatMessageHis
    * Retrieves the chat messages from the Redis database.
    * @returns An array of BaseMessage instances representing the chat history.
    */
-  async getMessages(): Promise<BaseMessage[]> {
-    const length = this.topLevelChatHistoryLength ?? [0, -1];
+  async getMessages(options?: { offset?: number; length?: number }): Promise<BaseMessage[]> {
+    const _length = options
+      ? [options.offset ?? 0, options.length ?? -1]
+      : this.topLevelChatHistoryLength ?? [0, -1];
 
     const rawStoredMessages: StoredMessage[] = await this.client.lrange<StoredMessage>(
       this.sessionId,
-      typeof length === "number" ? 0 : length[0],
-      typeof length === "number" ? length : length[1]
+      typeof _length === "number" ? 0 : _length[0],
+      typeof _length === "number" ? _length : _length[1]
     );
 
     const orderedMessages = rawStoredMessages.reverse();

src/rag-chat.ts

@@ -104,13 +104,12 @@ export class RAGChat extends RAGChatBase {
   }
 
   /** Method to get history of messages used in the RAG Chat*/
-  getHistory(options: HistoryOptions) {
+  getMessageHistory(options: HistoryOptions) {
     return this.historyService
       .getMessageHistory({
         sessionId: options.sessionId ?? DEFAULT_CHAT_SESSION_ID,
-        length: options.historyLength,
       })
-      .getMessages();
+      .getMessages({ length: options.length, offset: options.offset });
   }
 
   /** Method to clear history of messages used in the RAG Chat*/

src/types.ts

@@ -122,4 +122,27 @@ export type AddContextOptions = {
   namespace?: string;
 };
 
-export type HistoryOptions = Pick<ChatOptions, "historyLength" | "sessionId">;
+export type HistoryOptions = {
+  /**
+   * Specifies the number of messages to get from the conversation history.
+   * A negative value (default is -1) means the entire conversation history will be retrieved.
+   * Set this to a positive number to limit the history to that many recent messages.
+   *
+   * @default -1
+   */
+  length?: number;
+
+  /**
+   * Defines the number of most recent messages to skip in the conversation history.
+   * For example, if offset is set to 2, the two most recent messages will be skipped.
+   * Default value is 0, meaning no messages will be skipped.
+   *
+   * @default 0
+   */
+  offset?: number;
+
+  /** Chat session ID of the user interacting with the application.
+   * @default "upstash-rag-chat-session"
+   */
+  sessionId?: string;
+};