Fix: Upstash Redis lookup parse value bug (langchain-ai#2765)

* fix: bug in upstash redis lookup

* nit

* fix: /* eslint-disable no-process-env */

* chore: lint

* fix: type get result as StoredGeneration

* fix: proper types on non int test

---------

Co-authored-by: jacoblee93 <[email protected]>

langchain/src/cache/tests/upstash_redis.int.test.ts

@@ -0,0 +1,38 @@
+/* eslint-disable no-process-env */
+import { ChatOpenAI } from "../../chat_models/openai.js";
+import { UpstashRedisCache } from "../upstash_redis.js";
+
+/**
+ * This test is a result of the `lookup` method trying to parse an
+ * incorrectly typed value Before it was being typed as a string,
+ * whereas in reality it was a JSON object.
+ */
+test.skip("UpstashRedisCache does not parse non string cached values", async () => {
+  if (
+    !process.env.UPSTASH_REDIS_REST_URL ||
+    !process.env.UPSTASH_REDIS_REST_TOKEN ||
+    !process.env.OPENAI_API_KEY
+  ) {
+    throw new Error(
+      "Missing Upstash Redis REST URL // REST TOKEN or OpenAI API key"
+    );
+  }
+  const upstashRedisCache = new UpstashRedisCache({
+    config: {
+      url: process.env.UPSTASH_REDIS_REST_URL,
+      token: process.env.UPSTASH_REDIS_REST_TOKEN,
+    },
+  });
+
+  const chat = new ChatOpenAI({
+    temperature: 0,
+    cache: upstashRedisCache,
+    maxTokens: 10,
+  });
+
+  const prompt = "is the sky blue";
+  const result1 = await chat.predict(prompt);
+  const result2 = await chat.predict(prompt);
+
+  expect(result1).toEqual(result2);
+});

langchain/src/cache/tests/upstash_redis.test.ts

@@ -2,14 +2,15 @@ import { test, expect, jest } from "@jest/globals";
 import hash from "object-hash";
 
 import { UpstashRedisCache } from "../upstash_redis.js";
+import { StoredGeneration } from "../../schema/index.js";
 
 const sha256 = (str: string) => hash(str);
 
 test("UpstashRedisCache", async () => {
   const redis = {
-    get: jest.fn(async (key: string) => {
+    get: jest.fn(async (key: string): Promise<StoredGeneration | null> => {
       if (key === sha256("foo_bar_0")) {
-        return JSON.stringify({ text: "baz" });
+        return { text: "baz" };
       }
       return null;
     }),

langchain/src/cache/upstash_redis.ts

@@ -1,6 +1,6 @@
 import { Redis, type RedisConfigNodejs } from "@upstash/redis";
 
-import { BaseCache, Generation } from "../schema/index.js";
+import { BaseCache, Generation, StoredGeneration } from "../schema/index.js";
 import {
   deserializeStoredGeneration,
   getCacheKey,
@@ -46,14 +46,14 @@ export class UpstashRedisCache extends BaseCache {
   public async lookup(prompt: string, llmKey: string) {
     let idx = 0;
     let key = getCacheKey(prompt, llmKey, String(idx));
-    let value: string | null = await this.redisClient.get(key);
+    let value = await this.redisClient.get<StoredGeneration | null>(key);
     const generations: Generation[] = [];
 
     while (value) {
-      generations.push(deserializeStoredGeneration(JSON.parse(value)));
+      generations.push(deserializeStoredGeneration(value));
       idx += 1;
       key = getCacheKey(prompt, llmKey, String(idx));
-      value = await this.redisClient.get(key);
+      value = await this.redisClient.get<StoredGeneration | null>(key);
     }
 
     return generations.length > 0 ? generations : null;