唐小鸭 50fa524a6d partners: (langchain-deepseek) fix deepseek-r1 always returns an empty reasoning_content when reasoning (#31065) ...

## Description
deepseek-r1 always returns an empty string `reasoning_content` to the
first chunk when thinking, and sets `reasoning_content` to None when
thinking is over, to determine when to switch to normal output.

Therefore, whether the reasoning_content field exists should be judged
as None.

## Demo
deepseek-r1 reasoning output: 

```
{'delta': {'content': None, 'function_call': None, 'refusal': None, 'role': 'assistant', 'tool_calls': None, 'reasoning_content': ''}, 'finish_reason': None, 'index': 0, 'logprobs': None}
{'delta': {'content': None, 'function_call': None, 'refusal': None, 'role': None, 'tool_calls': None, 'reasoning_content': '好的'}, 'finish_reason': None, 'index': 0, 'logprobs': None}
{'delta': {'content': None, 'function_call': None, 'refusal': None, 'role': None, 'tool_calls': None, 'reasoning_content': '，'}, 'finish_reason': None, 'index': 0, 'logprobs': None}
{'delta': {'content': None, 'function_call': None, 'refusal': None, 'role': None, 'tool_calls': None, 'reasoning_content': '用户'}, 'finish_reason': None, 'index': 0, 'logprobs': None}
...
```

deepseek-r1 first normal output
```
...
{'delta': {'content': ' main', 'function_call': None, 'refusal': None, 'role': None, 'tool_calls': None, 'reasoning_content': None}, 'finish_reason': None, 'index': 0, 'logprobs': None}
{'delta': {'content': '\n\nimport', 'function_call': None, 'refusal': None, 'role': None, 'tool_calls': None, 'reasoning_content': None}, 'finish_reason': None, 'index': 0, 'logprobs': None}
...
```

---------

Co-authored-by: ccurme <chester.curme@gmail.com>

2025-05-05 22:31:58 +00:00

..

__init__.py

…

chat_models.py

partners: (langchain-deepseek) fix deepseek-r1 always returns an empty reasoning_content when reasoning (#31065)

2025-05-05 22:31:58 +00:00

py.typed

…