Abdullahsab3 commented on code in PR #11347: URL: https://github.com/apache/datafusion/pull/11347#discussion_r1670830134
########## datafusion/functions/src/datetime/to_local_time.rs: ########## @@ -0,0 +1,601 @@ +// Licensed to the Apache Software Foundation (ASF) under one +// or more contributor license agreements. See the NOTICE file +// distributed with this work for additional information +// regarding copyright ownership. The ASF licenses this file +// to you under the Apache License, Version 2.0 (the +// "License"); you may not use this file except in compliance +// with the License. You may obtain a copy of the License at +// +// http://www.apache.org/licenses/LICENSE-2.0 +// +// Unless required by applicable law or agreed to in writing, +// software distributed under the License is distributed on an +// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +// KIND, either express or implied. See the License for the +// specific language governing permissions and limitations +// under the License. + +use std::any::Any; +use std::ops::Add; +use std::sync::Arc; + +use arrow::array::timezone::Tz; +use arrow::array::{ArrayRef, PrimitiveArray}; +use arrow::datatypes::DataType::Timestamp; +use arrow::datatypes::{ + ArrowTimestampType, DataType, TimestampMicrosecondType, TimestampMillisecondType, + TimestampNanosecondType, TimestampSecondType, +}; +use arrow::datatypes::{ + TimeUnit, + TimeUnit::{Microsecond, Millisecond, Nanosecond, Second}, +}; + +use chrono::{Offset, TimeDelta, TimeZone, Utc}; +use datafusion_common::cast::as_primitive_array; +use datafusion_common::{exec_err, Result, ScalarValue}; +use datafusion_expr::TypeSignature::Exact; +use datafusion_expr::{ + ColumnarValue, ScalarUDFImpl, Signature, Volatility, TIMEZONE_WILDCARD, +}; + +/// A UDF function that converts a timezone-aware timestamp to local time (with no offset or +/// timezone information). In other words, this function strips off the timezone from the timestamp, +/// while keep the display value of the timestamp the same. +/// +/// # Example 1 +/// +/// ``` +/// # use datafusion_common::ScalarValue; +/// # use datafusion_expr::ColumnarValue; +/// # use datafusion_functions::datetime::to_local_time::ToLocalTimeFunc; +/// # use datafusion_expr::ScalarUDFImpl; +/// +/// // 2019-03-31 01:00:00 +01:00 +/// let res = ToLocalTimeFunc::new() +/// .invoke(&[ColumnarValue::Scalar(ScalarValue::TimestampSecond( +/// Some(1_553_990_400), +/// Some("Europe/Brussels".into()), +/// ))]) +/// .unwrap(); +/// +/// // 2019-03-31 01:00:00 <-- this timestamp no longer has +01:00 offset +/// let expected = ScalarValue::TimestampSecond(Some(1_553_994_000), None); +/// +/// match res { +/// ColumnarValue::Scalar(res) => { +/// assert_eq!(res, expected); +/// } +/// _ => panic!("unexpected return type"), +/// } +/// ``` +/// +/// # Example 2 +/// +/// ``` +/// # use datafusion_common::ScalarValue; +/// # use datafusion_expr::ColumnarValue; +/// # use chrono::NaiveDateTime; +/// # use datafusion_functions::datetime::to_local_time::ToLocalTimeFunc; +/// # use datafusion_expr::ScalarUDFImpl; +/// +/// let timestamp_str = "2020-03-31T13:40:00"; +/// let timezone_str = "America/New_York"; +/// let tz: arrow::array::timezone::Tz = +/// timezone_str.parse().expect("Invalid timezone"); +/// +/// let timestamp = timestamp_str +/// .parse::<NaiveDateTime>() +/// .unwrap() +/// .and_local_timezone(tz) // this is in a local timezone +/// .unwrap() +/// .timestamp_nanos_opt() +/// .unwrap(); +/// +/// let expected_timestamp = timestamp_str +/// .parse::<NaiveDateTime>() +/// .unwrap() +/// .and_utc() // this is in UTC +/// .timestamp_nanos_opt() +/// .unwrap(); +/// +/// let input = +/// ScalarValue::TimestampNanosecond(Some(timestamp), Some(timezone_str.into())); +/// let res = ToLocalTimeFunc::new() +/// .invoke(&[ColumnarValue::Scalar(input)]) +/// .unwrap(); +/// let expected = ScalarValue::TimestampNanosecond(Some(expected_timestamp), None); +/// match res { +/// ColumnarValue::Scalar(res) => { +/// assert_eq!(res, expected); +/// } +/// _ => panic!("unexpected return type"), +/// } +/// ``` +#[derive(Debug)] +pub struct ToLocalTimeFunc { + signature: Signature, +} + +impl Default for ToLocalTimeFunc { + fn default() -> Self { + Self::new() + } +} + +impl ToLocalTimeFunc { + pub fn new() -> Self { + let base_sig = |array_type: TimeUnit| { + vec![ + Exact(vec![Timestamp(array_type, None)]), + Exact(vec![Timestamp(array_type, Some(TIMEZONE_WILDCARD.into()))]), + ] + }; + + let full_sig = [Nanosecond, Microsecond, Millisecond, Second] + .into_iter() + .map(base_sig) + .collect::<Vec<_>>() + .concat(); + + Self { + signature: Signature::one_of(full_sig, Volatility::Immutable), + } + } + + fn to_local_time(&self, args: &[ColumnarValue]) -> Result<ColumnarValue> { + if args.len() != 1 { + return exec_err!( + "to_local_time function requires 1 argument, got {}", + args.len() + ); + } + + let time_value = args[0].clone(); + let arg_type = time_value.data_type(); + match arg_type { + DataType::Timestamp(_, None) => { + // if no timezone specificed, just return the input + Ok(time_value.clone()) + } + // if has timezone, adjust the underlying time value. the current time value + // is stored as i64 in UTC, even though the timezone may not be in UTC, so + // we need to adjust the time value to the local time. see [`adjust_to_local_time`] + // for more details. + // + // Then remove the timezone in return type, i.e. return None + DataType::Timestamp(_, Some(_)) => match time_value { + ColumnarValue::Scalar(ScalarValue::TimestampNanosecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampNanosecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampNanosecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Scalar(ScalarValue::TimestampMicrosecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampMicrosecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampMicrosecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Scalar(ScalarValue::TimestampMillisecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampMillisecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampMillisecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Scalar(ScalarValue::TimestampSecond( + Some(ts), + Some(tz), + )) => { + let adjusted_ts = + adjust_to_local_time::<TimestampSecondType>(ts, &tz); + Ok(ColumnarValue::Scalar(ScalarValue::TimestampSecond( + Some(adjusted_ts), + None, + ))) + } + ColumnarValue::Array(array) => { + fn transform_array<T>( + array: &ArrayRef, + tz: &str, + ) -> Result<ColumnarValue> + where + T: ArrowTimestampType, + { + let array = as_primitive_array::<T>(array)?; + let array: PrimitiveArray<T> = + array.unary(|ts| adjust_to_local_time::<T>(ts, tz)); Review Comment: minor remark: You can have both `array` definitions in the same definition to avoid shadowing ```suggestion let array = as_primitive_array::<T>(array)?.unary(|ts| adjust_to_local_time::<T>(ts, tz)); ``` (my linting might be off :p) Thinking outloud here, but perhaps it's better to follow the same naming convention as for the scalar types. i.e: ```suggestion let array = as_primitive_array::<T>(array)?; let adjusted_array = .unary(|ts| adjust_to_local_time::<T>(ts, tz)); ``` in which case the returned value needs to be changed to: ```Rust Ok(ColumnarValue::Array(Arc::new(adjusted_array))) ``` -- This is an automated message from the Apache Git Service. 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