openai[patch]: fix ChatOpenAI model's openai proxy (langchain-ai#19559)

Due to changes in the OpenAI SDK, the previous method of setting the
OpenAI proxy in ChatOpenAI no longer works. This PR fixes this issue,
making the previous way of setting the OpenAI proxy in ChatOpenAI
effective again.

---------

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

Author: Sukitly

libs/partners/openai/langchain_openai/chat_models/base.py

@@ -380,12 +380,31 @@ def validate_environment(cls, values: Dict) -> Dict:
             "default_query": values["default_query"],
         }
 
+        openai_proxy = values["openai_proxy"]
         if not values.get("client"):
+            if openai_proxy and not values["http_client"]:
+                try:
+                    import httpx
+                except ImportError as e:
+                    raise ImportError(
+                        "Could not import httpx python package. "
+                        "Please install it with `pip install httpx`."
+                    ) from e
+                values["http_client"] = httpx.Client(proxy=openai_proxy)
             sync_specific = {"http_client": values["http_client"]}
             values["client"] = openai.OpenAI(
                 **client_params, **sync_specific
             ).chat.completions
         if not values.get("async_client"):
+            if openai_proxy and not values["http_async_client"]:
+                try:
+                    import httpx
+                except ImportError as e:
+                    raise ImportError(
+                        "Could not import httpx python package. "
+                        "Please install it with `pip install httpx`."
+                    ) from e
+                values["http_async_client"] = httpx.AsyncClient(proxy=openai_proxy)
             async_specific = {"http_client": values["http_async_client"]}
             values["async_client"] = openai.AsyncOpenAI(
                 **client_params, **async_specific

libs/partners/openai/tests/integration_tests/chat_models/test_base.py

@@ -501,3 +501,25 @@ class MyModel(BaseModel):
     assert isinstance(result, MyModel)
     assert result.name == "Erick"
     assert result.age == 27
+
+
+def test_openai_proxy() -> None:
+    """Test ChatOpenAI with proxy."""
+    chat_openai = ChatOpenAI(
+        openai_proxy="http://localhost:8080",
+    )
+    mounts = chat_openai.client._client._client._mounts
+    assert len(mounts) == 1
+    for key, value in mounts.items():
+        proxy = value._pool._proxy_url.origin
+        assert proxy.scheme == b"http"
+        assert proxy.host == b"localhost"
+        assert proxy.port == 8080
+
+    async_client_mounts = chat_openai.async_client._client._client._mounts
+    assert len(async_client_mounts) == 1
+    for key, value in async_client_mounts.items():
+        proxy = value._pool._proxy_url.origin
+        assert proxy.scheme == b"http"
+        assert proxy.host == b"localhost"
+        assert proxy.port == 8080