def query_most_recent_date(session: Session, keyspace: str,
table: str) -> Optional[str]:
"""Fetch most recent entry from exchange rates table."""
def pandas_factory(colnames, rows):
return pd.DataFrame(rows, columns=colnames)
session.row_factory = pandas_factory
query = f"""SELECT date FROM {keyspace}.{table};"""
result = session.execute(query)
rates = result._current_rows
if rates.empty:
max_date = None
else:
rates["date"] = rates["date"].astype("datetime64")
max_date = (rates.nlargest(
1, "date").iloc[0]["date"].strftime("%Y-%m-%d"))
return max_date
