get_format_instructions() — langchain Function Reference

Architecture documentation for the get_format_instructions() function in datetime.py from the langchain codebase.

Function python OutputParsing StreamingParsers calls 1 called by 1

Entity Profile

OutputParsing→ StreamingParsers→ get_format_instructions() — langchain Function Reference

Dependency Diagram

graph TD
  595e7325_93dc_d4e6_4162_86aa22edf649["get_format_instructions()"]
  2f806e11_8650_3820_0781_ec967e39cb53["DatetimeOutputParser"]
  595e7325_93dc_d4e6_4162_86aa22edf649 -->|defined in| 2f806e11_8650_3820_0781_ec967e39cb53
  595e7325_93dc_d4e6_4162_86aa22edf649["get_format_instructions()"]
  595e7325_93dc_d4e6_4162_86aa22edf649 -->|calls| 595e7325_93dc_d4e6_4162_86aa22edf649
  595e7325_93dc_d4e6_4162_86aa22edf649["get_format_instructions()"]
  595e7325_93dc_d4e6_4162_86aa22edf649 -->|calls| 595e7325_93dc_d4e6_4162_86aa22edf649
  style 595e7325_93dc_d4e6_4162_86aa22edf649 fill:#6366f1,stroke:#818cf8,color:#fff

Relationship Graph

Source Code

libs/langchain/langchain_classic/output_parsers/datetime.py lines 17–46

    def get_format_instructions(self) -> str:
        """Returns the format instructions for the given format."""
        if self.format == "%Y-%m-%dT%H:%M:%S.%fZ":
            examples = comma_list(
                [
                    "2023-07-04T14:30:00.000000Z",
                    "1999-12-31T23:59:59.999999Z",
                    "2025-01-01T00:00:00.000000Z",
                ],
            )
        else:
            try:
                now = datetime.now(tz=timezone.utc)
                examples = comma_list(
                    [
                        now.strftime(self.format),
                        (now.replace(year=now.year - 1)).strftime(self.format),
                        (now - timedelta(days=1)).strftime(self.format),
                    ],
                )
            except ValueError:
                # Fallback if the format is very unusual
                examples = f"e.g., a valid string in the format {self.format}"

        return (
            f"Write a datetime string that matches the "
            f"following pattern: '{self.format}'.\n\n"
            f"Examples: {examples}\n\n"
            f"Return ONLY this string, no other words!"
        )