core[minor]: exclude model cache from serialization (langchain-ai#6929)

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

Author: baskaryan

langchain-core/src/language_models/base.ts

@@ -363,13 +363,14 @@ export abstract class BaseLanguageModel<
     callbackManager,
     ...params
   }: BaseLanguageModelParams) {
+    const { cache, ...rest } = params;
     super({
       callbacks: callbacks ?? callbackManager,
-      ...params,
+      ...rest,
     });
-    if (typeof params.cache === "object") {
-      this.cache = params.cache;
-    } else if (params.cache) {
+    if (typeof cache === "object") {
+      this.cache = cache;
+    } else if (cache) {
       this.cache = InMemoryCache.global();
     } else {
       this.cache = undefined;

langchain-core/src/language_models/tests/chat_models.test.ts

@@ -323,3 +323,15 @@ test("Test ChatModel can stream back a custom event", async () => {
   }
   expect(customEvent).toBeDefined();
 });
+
+test(`Test ChatModel should not serialize a passed "cache" parameter`, async () => {
+  const model = new FakeListChatModel({
+    responses: ["hi"],
+    emitCustomEvent: true,
+    cache: true,
+  });
+  console.log(JSON.stringify(model));
+  expect(JSON.stringify(model)).toEqual(
+    `{"lc":1,"type":"constructor","id":["langchain","chat_models","fake-list","FakeListChatModel"],"kwargs":{"responses":["hi"],"emit_custom_event":true}}`
+  );
+});

langchain-core/src/utils/testing/index.ts

@@ -354,6 +354,8 @@ export class FakeListChatModel extends BaseChatModel<FakeListChatModelCallOption
     return "FakeListChatModel";
   }
 
+  lc_serializable = true;
+
   responses: string[];
 
   i = 0;
@@ -362,8 +364,9 @@ export class FakeListChatModel extends BaseChatModel<FakeListChatModelCallOption
 
   emitCustomEvent = false;
 
-  constructor({ responses, sleep, emitCustomEvent }: FakeChatInput) {
-    super({});
+  constructor(params: FakeChatInput) {
+    super(params);
+    const { responses, sleep, emitCustomEvent } = params;
     this.responses = responses;
     this.sleep = sleep;
     this.emitCustomEvent = emitCustomEvent ?? this.emitCustomEvent;