Fix output types for BaseChatModel (#11670)

* Should use non chunked messages for Invoke/Batch
* After this PR, stream output type is not represented, do we want to
use the union?

---------

Co-authored-by: Erick Friis <erick@langchain.dev>

libs/langchain/langchain/chat_models/base.py

@@ -38,14 +38,12 @@ from langchain.schema import (
 from langchain.schema.language_model import BaseLanguageModel, LanguageModelInput
 from langchain.schema.messages import (
     AIMessage,
-    AIMessageChunk,
     BaseMessage,
     BaseMessageChunk,
-    ChatMessageChunk,
-    FunctionMessageChunk,
+    ChatMessage,
+    FunctionMessage,
     HumanMessage,
-    HumanMessageChunk,
-    SystemMessageChunk,
+    SystemMessage,
 )
 from langchain.schema.output import ChatGenerationChunk
 from langchain.schema.runnable import RunnableConfig
@@ -115,13 +113,9 @@ class BaseChatModel(BaseLanguageModel[BaseMessageChunk], ABC):
 
     @property
     def OutputType(self) -> Any:
-        """Get the input type for this runnable."""
+        """Get the output type for this runnable."""
         return Union[
-            HumanMessageChunk,
-            AIMessageChunk,
-            ChatMessageChunk,
-            FunctionMessageChunk,
-            SystemMessageChunk,
+            HumanMessage, AIMessage, ChatMessage, FunctionMessage, SystemMessage
         ]
 
     def _convert_input(self, input: LanguageModelInput) -> PromptValue:

libs/langchain/tests/unit_tests/schema/runnable/__snapshots__/test_runnable.ambr

@@ -2163,24 +2163,24 @@
   dict({
     'anyOf': list([
       dict({
-        '$ref': '#/definitions/HumanMessageChunk',
+        '$ref': '#/definitions/HumanMessage',
       }),
       dict({
-        '$ref': '#/definitions/AIMessageChunk',
+        '$ref': '#/definitions/AIMessage',
       }),
       dict({
-        '$ref': '#/definitions/ChatMessageChunk',
+        '$ref': '#/definitions/ChatMessage',
       }),
       dict({
-        '$ref': '#/definitions/FunctionMessageChunk',
+        '$ref': '#/definitions/FunctionMessage',
       }),
       dict({
-        '$ref': '#/definitions/SystemMessageChunk',
+        '$ref': '#/definitions/SystemMessage',
       }),
     ]),
     'definitions': dict({
-      'AIMessageChunk': dict({
-        'description': 'A Message chunk from an AI.',
+      'AIMessage': dict({
+        'description': 'A Message from an AI.',
         'properties': dict({
           'additional_kwargs': dict({
             'title': 'Additional Kwargs',
@@ -2196,9 +2196,9 @@
             'type': 'boolean',
           }),
           'type': dict({
-            'default': 'AIMessageChunk',
+            'default': 'ai',
             'enum': list([
-              'AIMessageChunk',
+              'ai',
             ]),
             'title': 'Type',
             'type': 'string',
@@ -2207,11 +2207,11 @@
         'required': list([
           'content',
         ]),
-        'title': 'AIMessageChunk',
+        'title': 'AIMessage',
         'type': 'object',
       }),
-      'ChatMessageChunk': dict({
-        'description': 'A Chat Message chunk.',
+      'ChatMessage': dict({
+        'description': 'A Message that can be assigned an arbitrary speaker (i.e. role).',
         'properties': dict({
           'additional_kwargs': dict({
             'title': 'Additional Kwargs',
@@ -2226,9 +2226,9 @@
             'type': 'string',
           }),
           'type': dict({
-            'default': 'ChatMessageChunk',
+            'default': 'chat',
             'enum': list([
-              'ChatMessageChunk',
+              'chat',
             ]),
             'title': 'Type',
             'type': 'string',
@@ -2238,11 +2238,11 @@
           'content',
           'role',
         ]),
-        'title': 'ChatMessageChunk',
+        'title': 'ChatMessage',
         'type': 'object',
       }),
-      'FunctionMessageChunk': dict({
-        'description': 'A Function Message chunk.',
+      'FunctionMessage': dict({
+        'description': 'A Message for passing the result of executing a function back to a model.',
         'properties': dict({
           'additional_kwargs': dict({
             'title': 'Additional Kwargs',
@@ -2257,9 +2257,9 @@
             'type': 'string',
           }),
           'type': dict({
-            'default': 'FunctionMessageChunk',
+            'default': 'function',
             'enum': list([
-              'FunctionMessageChunk',
+              'function',
             ]),
             'title': 'Type',
             'type': 'string',
@@ -2269,11 +2269,11 @@
           'content',
           'name',
         ]),
-        'title': 'FunctionMessageChunk',
+        'title': 'FunctionMessage',
         'type': 'object',
       }),
-      'HumanMessageChunk': dict({
-        'description': 'A Human Message chunk.',
+      'HumanMessage': dict({
+        'description': 'A Message from a human.',
         'properties': dict({
           'additional_kwargs': dict({
             'title': 'Additional Kwargs',
@@ -2289,9 +2289,9 @@
             'type': 'boolean',
           }),
           'type': dict({
-            'default': 'HumanMessageChunk',
+            'default': 'human',
             'enum': list([
-              'HumanMessageChunk',
+              'human',
             ]),
             'title': 'Type',
             'type': 'string',
@@ -2300,11 +2300,14 @@
         'required': list([
           'content',
         ]),
-        'title': 'HumanMessageChunk',
+        'title': 'HumanMessage',
         'type': 'object',
       }),
-      'SystemMessageChunk': dict({
-        'description': 'A System Message chunk.',
+      'SystemMessage': dict({
+        'description': '''
+          A Message for priming AI behavior, usually passed in as the first of a sequence
+          of input messages.
+        ''',
         'properties': dict({
           'additional_kwargs': dict({
             'title': 'Additional Kwargs',
@@ -2315,9 +2318,9 @@
             'type': 'string',
           }),
           'type': dict({
-            'default': 'SystemMessageChunk',
+            'default': 'system',
             'enum': list([
-              'SystemMessageChunk',
+              'system',
             ]),
             'title': 'Type',
             'type': 'string',
@@ -2326,7 +2329,7 @@
         'required': list([
           'content',
         ]),
-        'title': 'SystemMessageChunk',
+        'title': 'SystemMessage',
         'type': 'object',
       }),
     }),