community[patch]: Fix MiniMaxChat validate_environment error (#23770)

- **Description:** Fix some issues in MiniMaxChat 
  - Fix `minimax_api_host` not in `values` error
- Remove `minimax_group_id` from reading environment variables, the
`minimax_group_id` no longer use in MiniMaxChat
  - Invoke callback prior to yielding token, the issus #16913

libs/community/langchain_community/chat_models/minimax.py

@@ -186,15 +186,20 @@ class MiniMaxChat(BaseChatModel):
                 "MINIMAX_API_KEY",
             )
         )
-        values["minimax_group_id"] = get_from_dict_or_env(
-            values, ["minimax_group_id", "group_id"], "MINIMAX_GROUP_ID"
-        )
+
+        default_values = {
+            name: field.default
+            for name, field in cls.__fields__.items()
+            if field.default is not None
+        }
+        default_values.update(values)
+
         # Get custom api url from environment.
         values["minimax_api_host"] = get_from_dict_or_env(
             values,
-            "minimax_api_host",
+            ["minimax_api_host", "base_url"],
             "MINIMAX_API_HOST",
-            values["minimax_api_host"],
+            default_values["minimax_api_host"],
         )
         return values
 
@@ -316,9 +321,10 @@ class MiniMaxChat(BaseChatModel):
                     chunk = ChatGenerationChunk(
                         message=chunk, generation_info=generation_info
                     )
-                    yield chunk
                     if run_manager:
                         run_manager.on_llm_new_token(chunk.text, chunk=chunk)
+                    yield chunk
+
                     if finish_reason is not None:
                         break
 
@@ -394,8 +400,9 @@ class MiniMaxChat(BaseChatModel):
                     chunk = ChatGenerationChunk(
                         message=chunk, generation_info=generation_info
                     )
-                    yield chunk
                     if run_manager:
                         await run_manager.on_llm_new_token(chunk.text, chunk=chunk)
+                    yield chunk
+
                     if finish_reason is not None:
                         break

libs/community/tests/integration_tests/chat_models/test_minimax.py

@@ -0,0 +1,21 @@
+import os
+
+from langchain_core.messages import AIMessage
+
+from langchain_community.chat_models import MiniMaxChat
+
+
+def test_chat_minimax_not_group_id() -> None:
+    if "MINIMAX_GROUP_ID" in os.environ:
+        del os.environ["MINIMAX_GROUP_ID"]
+    chat = MiniMaxChat()  # type: ignore[call-arg]
+    response = chat.invoke("你好呀")
+    assert isinstance(response, AIMessage)
+    assert isinstance(response.content, str)
+
+
+def test_chat_minimax_with_stream() -> None:
+    chat = MiniMaxChat()  # type: ignore[call-arg]
+    for chunk in chat.stream("你好呀"):
+        assert isinstance(chunk, AIMessage)
+        assert isinstance(chunk.content, str)