init() — langchain Function Reference

Architecture documentation for the __init__() function in model_fallback.py from the langchain codebase.

Function python LangChainCore LanguageModelBase

Entity Profile

LangChainCore→ LanguageModelBase→ __init__() — langchain Function Reference

Dependency Diagram

graph TD
  82058868_f4c5_706a_3b45_4fe9fd5ab6cf["__init__()"]
  eb36575f_ada3_a10f_f140_390f57f60565["ModelFallbackMiddleware"]
  82058868_f4c5_706a_3b45_4fe9fd5ab6cf -->|defined in| eb36575f_ada3_a10f_f140_390f57f60565
  style 82058868_f4c5_706a_3b45_4fe9fd5ab6cf fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain_v1/langchain/agents/middleware/model_fallback.py lines 50–70

    def __init__(
        self,
        first_model: str | BaseChatModel,
        *additional_models: str | BaseChatModel,
    ) -> None:
        """Initialize model fallback middleware.

        Args:
            first_model: First fallback model (string name or instance).
            *additional_models: Additional fallbacks in order.
        """
        super().__init__()

        # Initialize all fallback models
        all_models = (first_model, *additional_models)
        self.models: list[BaseChatModel] = []
        for model in all_models:
            if isinstance(model, str):
                self.models.append(init_chat_model(model))
            else:
                self.models.append(model)