on_chat_model_start() — langchain Function Reference

Architecture documentation for the on_chat_model_start() function in base.py from the langchain codebase.

Function python Observability Tracers calls 4 called by 1

Entity Profile

Observability→ Tracers→ on_chat_model_start() — langchain Function Reference

Dependency Diagram

graph TD
  5409dd91_c8ea_0b1e_a8b7_b649883eb2c8["on_chat_model_start()"]
  b3ab8001_c14c_4191_ca53_2dbabc99917f["AsyncBaseTracer"]
  5409dd91_c8ea_0b1e_a8b7_b649883eb2c8 -->|defined in| b3ab8001_c14c_4191_ca53_2dbabc99917f
  43b37584_385d_a973_422d_989a637f7069["on_chat_model_start()"]
  43b37584_385d_a973_422d_989a637f7069 -->|calls| 5409dd91_c8ea_0b1e_a8b7_b649883eb2c8
  6f36dacc_adf3_1223_4aff_3ae256a05ed8["_start_trace()"]
  5409dd91_c8ea_0b1e_a8b7_b649883eb2c8 -->|calls| 6f36dacc_adf3_1223_4aff_3ae256a05ed8
  026587b1_ac0d_b217_1855_a63a386850c6["_on_chat_model_start()"]
  5409dd91_c8ea_0b1e_a8b7_b649883eb2c8 -->|calls| 026587b1_ac0d_b217_1855_a63a386850c6
  43b37584_385d_a973_422d_989a637f7069["on_chat_model_start()"]
  5409dd91_c8ea_0b1e_a8b7_b649883eb2c8 -->|calls| 43b37584_385d_a973_422d_989a637f7069
  e367264b_d5e2_1e7f_2b3a_e362236bcd24["_start_trace()"]
  5409dd91_c8ea_0b1e_a8b7_b649883eb2c8 -->|calls| e367264b_d5e2_1e7f_2b3a_e362236bcd24
  style 5409dd91_c8ea_0b1e_a8b7_b649883eb2c8 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/core/langchain_core/tracers/base.py lines 563–590

    async def on_chat_model_start(
        self,
        serialized: dict[str, Any],
        messages: list[list[BaseMessage]],
        *,
        run_id: UUID,
        parent_run_id: UUID | None = None,
        tags: list[str] | None = None,
        metadata: dict[str, Any] | None = None,
        name: str | None = None,
        **kwargs: Any,
    ) -> Any:
        chat_model_run = self._create_chat_model_run(
            serialized=serialized,
            messages=messages,
            run_id=run_id,
            parent_run_id=parent_run_id,
            tags=tags,
            metadata=metadata,
            name=name,
            **kwargs,
        )
        tasks = [
            self._start_trace(chat_model_run),
            self._on_chat_model_start(chat_model_run),
        ]
        await asyncio.gather(*tasks)
        return chat_model_run