apply_strategy() — langchain Function Reference

Architecture documentation for the apply_strategy() function in _redaction.py from the langchain codebase.

Function python LangChainCore MessageInterface calls 3 called by 1

Entity Profile

LangChainCore→ MessageInterface→ apply_strategy() — langchain Function Reference

Dependency Diagram

graph TD
  a830b2dc_75ff_a1e7_d25c_7de2223efe55["apply_strategy()"]
  be639235_9a02_cc2d_5a7d_637d822fb3b3["_redaction.py"]
  a830b2dc_75ff_a1e7_d25c_7de2223efe55 -->|defined in| be639235_9a02_cc2d_5a7d_637d822fb3b3
  fae00189_d2f4_7398_49ea_3100608cdf41["apply()"]
  fae00189_d2f4_7398_49ea_3100608cdf41 -->|calls| a830b2dc_75ff_a1e7_d25c_7de2223efe55
  098fc190_8120_3755_549b_42f1179f630e["_apply_redact_strategy()"]
  a830b2dc_75ff_a1e7_d25c_7de2223efe55 -->|calls| 098fc190_8120_3755_549b_42f1179f630e
  4c3aef38_195f_f867_1993_4e146c3618c0["_apply_mask_strategy()"]
  a830b2dc_75ff_a1e7_d25c_7de2223efe55 -->|calls| 4c3aef38_195f_f867_1993_4e146c3618c0
  59dbcc65_5bbf_d10e_9919_eaec975a7579["_apply_hash_strategy()"]
  a830b2dc_75ff_a1e7_d25c_7de2223efe55 -->|calls| 59dbcc65_5bbf_d10e_9919_eaec975a7579
  style a830b2dc_75ff_a1e7_d25c_7de2223efe55 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain_v1/langchain/agents/middleware/_redaction.py lines 306–336

def apply_strategy(
    content: str,
    matches: list[PIIMatch],
    strategy: RedactionStrategy,
) -> str:
    """Apply the configured strategy to matches within content.

    Args:
        content: The content to apply strategy to.
        matches: List of detected PII matches.
        strategy: The redaction strategy to apply.

    Returns:
        The content with the strategy applied.

    Raises:
        PIIDetectionError: If the strategy is `'block'` and matches are found.
        ValueError: If the strategy is unknown.
    """
    if not matches:
        return content
    if strategy == "redact":
        return _apply_redact_strategy(content, matches)
    if strategy == "mask":
        return _apply_mask_strategy(content, matches)
    if strategy == "hash":
        return _apply_hash_strategy(content, matches)
    if strategy == "block":
        raise PIIDetectionError(matches[0]["type"], matches)
    msg = f"Unknown redaction strategy: {strategy}"  # type: ignore[unreachable]
    raise ValueError(msg)