Source code for langchain.output_parsers.datetime

import random
from datetime import datetime, timedelta
from typing import List

from langchain_core.exceptions import OutputParserException
from langchain_core.output_parsers import BaseOutputParser
from langchain_core.utils import comma_list

def _generate_random_datetime_strings(
    pattern: str,
    n: int = 3,
    start_date: datetime = datetime(1, 1, 1),
    end_date: datetime = + timedelta(days=3650),
) -> List[str]:
    """Generates n random datetime strings conforming to the
    given pattern within the specified date range.

    Pattern should be a string containing the desired format codes.
    start_date and end_date should be datetime objects representing
    the start and end of the date range.
    examples = []
    delta = end_date - start_date
    for i in range(n):
        random_delta = random.uniform(0, delta.total_seconds())
        dt = start_date + timedelta(seconds=random_delta)
        date_string = dt.strftime(pattern)
    return examples

[docs]class DatetimeOutputParser(BaseOutputParser[datetime]): """Parse the output of an LLM call to a datetime.""" format: str = "%Y-%m-%dT%H:%M:%S.%fZ" """The string value that used as the datetime format."""
[docs] def get_format_instructions(self) -> str: examples = comma_list(_generate_random_datetime_strings(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!" )
[docs] def parse(self, response: str) -> datetime: try: return datetime.strptime(response.strip(), self.format) except ValueError as e: raise OutputParserException( f"Could not parse datetime string: {response}" ) from e
@property def _type(self) -> str: return "datetime"