How to exclude a certain input key from being traced?

[pprobst]

Hi. One of my input keys is an audio in base64 format, and it can get pretty large sometimes.
How can I exclude it from the traces in LangSmith?

Here is how LangSmith is setup and my current schema:

os.environ["LANGCHAIN_PROJECT"] = LANGCHAIN_PROJECT
os.environ["LANGCHAIN_API_KEY"] = LANGCHAIN_API_KEY
os.environ["LANGCHAIN_TRACING_V2"] = "true" if LANGCHAIN_API_KEY else "false"
os.environ["LANGCHAIN_ENDPOINT"] = "https://api.smith.langchain.com"

class TranscriptionForm(BaseModel):
    text: List[str] = []
    audio_base64: List[str] = [] # I want to exclude this from appearing in the traces!
    filename: List[str] = []
    template: str
    model: str = "gpt-4o-mini"
    user_id: str = ""
    user_rules: List[str] = []
    output_format: str = "string"  # or "json"

[pprobst]

The easiest solution was to change the type of the input I wanted to hide to Pydantic's SecretStr:

audio_base64: List[SecretStr] = []

Then, when you need to retrieve the value, you just:

for audio in audio_base64:
    if audio.__class__ == SecretStr:
        audio = audio.get_secret_value()

There are also other solutions, but since I'm using LangSmith with LangServe, just changing the type of one of the inputs to SecretStr works better for me.