Support casting strings to durations - #10516
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| None, | ||
| ]; | ||
|
|
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| macro_rules! test_duration { |
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this macro can probably be a generic
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| // Preserve the full i64 range for the common case of a unitless integer. | ||
| if let Ok(value) = value.parse::<i64>() { | ||
| return Ok(value); | ||
| } |
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i'm not sure about this behaviour as it does seem a bit implicit 🤔
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| // Duration display currently emits ISO 8601 values as a number of seconds, | ||
| // for example `PT1.5S` or `-PT1.5S`. Convert this to the interval parser's | ||
| // human-readable syntax so both representations share the same validation. | ||
| let normalized; | ||
| let value = if let Some(seconds) = value | ||
| .strip_prefix("PT") | ||
| .and_then(|value| value.strip_suffix('S')) | ||
| { | ||
| normalized = format!("{seconds} seconds"); | ||
| normalized.as_str() | ||
| } else if let Some(seconds) = value | ||
| .strip_prefix("-PT") | ||
| .and_then(|value| value.strip_suffix('S')) | ||
| { | ||
| normalized = format!("-{seconds} seconds"); | ||
| normalized.as_str() | ||
| } else { | ||
| value | ||
| }; |
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Do we need to consider other designators such as hours, minutes, etc.?
also is this possible to parse directly without reconstructing a string to pass through the interval parser?
| ) | ||
| }) { | ||
| return Err(ArrowError::CastError(format!( | ||
| "Cannot cast {value} to {}. Year and month fields are not supported.", |
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probably need the error message to be more generic here, as it disallows century, decade, etc.
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Which issue does this PR close?
Rationale for this change
arrow-castcan format durations as strings but does not currently support casting those strings back to duration arrays. This leaves duration casts asymmetric and prevents round-tripping formatted values.What changes are included in this PR?
Utf8,LargeUtf8, andUtf8Viewvalues to cast to all four duration units.Are these changes tested?
Yes. Tests cover all duration units, all supported string representations, safe and unsafe behavior, invalid calendar units, and ISO 8601 and pretty-format round trips.
Validation performed:
cargo test -p arrow-cast --lib(363 passed)cargo clippy -p arrow-cast --lib --tests -- -D warningscargo fmt --all -- --checkAre there any user-facing changes?
Yes. Users can now cast string arrays to duration arrays. This adds functionality without changing an existing public API.
Tooling disclosure
Generative tooling assisted with the parser implementation, cast dispatch arms, tests, and PR wording. The full patch was locally reviewed and verified with the checks above.