[Docs] Fix the example code of streaming chat completions in reasoning (#21825)

Signed-off-by: wangzi <3220100013@zju.edu.cn>
Co-authored-by: wangzi <3220100013@zju.edu.cn>
Co-authored-by: Zi Wang <66560864+BruceW-07@users.noreply.github.com>

docs/features/reasoning_outputs.md

@@ -123,13 +123,12 @@ OpenAI Python client library does not officially support `reasoning_content` att
     printed_content = False
 
     for chunk in stream:
-        reasoning_content = None
-        content = None
-        # Check the content is reasoning_content or content
-        if hasattr(chunk.choices[0].delta, "reasoning_content"):
-            reasoning_content = chunk.choices[0].delta.reasoning_content
-        elif hasattr(chunk.choices[0].delta, "content"):
-            content = chunk.choices[0].delta.content
+        # Safely extract reasoning_content and content from delta,
+        # defaulting to None if attributes don't exist or are empty strings
+        reasoning_content = (
+            getattr(chunk.choices[0].delta, "reasoning_content", None) or None
+        )
+        content = getattr(chunk.choices[0].delta, "content", None) or None
 
         if reasoning_content is not None:
             if not printed_reasoning_content:

examples/online_serving/openai_chat_completion_with_reasoning_streaming.py

@@ -51,13 +51,12 @@ def main():
     printed_content = False
 
     for chunk in stream:
-        reasoning_content = None
-        content = None
-        # Check the content is reasoning_content or content
-        if hasattr(chunk.choices[0].delta, "reasoning_content"):
-            reasoning_content = chunk.choices[0].delta.reasoning_content
-        elif hasattr(chunk.choices[0].delta, "content"):
-            content = chunk.choices[0].delta.content
+        # Safely extract reasoning_content and content from delta,
+        # defaulting to None if attributes don't exist or are empty strings
+        reasoning_content = (
+            getattr(chunk.choices[0].delta, "reasoning_content", None) or None
+        )
+        content = getattr(chunk.choices[0].delta, "content", None) or None
 
         if reasoning_content is not None:
             if not printed_reasoning_content: