pola-rs/polars

`pl.datetime` needs a way to fail silently

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#21,898 opened on Mar 23, 2025

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 (9 comments) (1 reaction) (0 assignees)Rust (2,826 forks)batch import
buggood first issueneeds triagepython

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Description

Checks

  • I have checked that this issue has not already been reported.
  • I have confirmed this bug exists on the latest version of Polars.

Reproducible example

import polars as pl

df = pl.DataFrame({
    'year': [2024],
    'month': [1],
    'day': [1],
    'hour': [1],
    'minute': [1],
    'second': [63],
})

res = df.select(
    pl.datetime('year', 'month', 'day', 'hour', 'minute', 'second')
)

Log output

Issue description

pl.datetime used to silently fail and output a null.

Due to https://github.com/pola-rs/polars/pull/21013 it now throws a ComputeError: Invalid time components.

I've got no issue with the new behavior, but can we add a flag back to fail with a null? Run into this with some data processing.

Thanks

Expected behavior

Given a flag it would output a null on ComputeError

Installed versions

--------Version info---------
Polars:              1.23.0
Index type:          UInt32
Platform:            Linux-6.12.7-arch1-1-x86_64-with-glibc2.41
Python:              3.12.5 | packaged by conda-forge | (main, Aug  8 2024, 18:36:51) [GCC 12.4.0]
LTS CPU:             False

----Optional dependencies----
Azure CLI            <not installed>
adbc_driver_manager  <not installed>
altair               5.4.1
azure.identity       <not installed>
boto3                1.34.59
cloudpickle          3.0.0
connectorx           <not installed>
deltalake            <not installed>
fastexcel            <not installed>
fsspec               2024.5.0
gevent               24.2.1
google.auth          2.28.2
great_tables         <not installed>
matplotlib           3.8.4
numpy                1.26.3
openpyxl             3.1.2
pandas               3.0.0.dev0+756.ge8e6be071c
polars_cloud         <not installed>
pyarrow              20.0.0.dev130+geae901e6aa.d20250226
pydantic             2.10.4
pyiceberg            <not installed>
sqlalchemy           2.0.30
torch                2.4.1+cu121
xlsx2csv             <not installed>
xlsxwriter           <not installed>```

</details>

Contributor guide

Research direction
The issue requests adding a parameter to `pl.datetime` to return null on invalid time components instead of throwing a ComputeError. The behavior was changed in PR #21013. The fix involves modifying the datetime expression to accept an optional error handling mode. Newcomers should look at the Rust implementation behind `pl.datetime` in the Polars codebase (e.g., in `polars core` or `polars lazy`). A parameter named `strict` or similar could be added to control error handling.
Tech stack
pythonrust
Domain
data
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
PythonRustPolars internals
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70