Improve JSON decoder errors (#4076) #4079
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tustvold
commented
Apr 13, 2023
| } | ||
| } | ||
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| /// Returns the number of rows | ||
| pub fn num_rows(&self) -> usize { | ||
| self.num_rows | ||
| } | ||
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| /// Serialize the tape element at index `idx` to `out` returning the next field index |
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It is worth noting that this necessarily cannot preserve whitespace, but it at least preserves structure
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This does not appear to materially impact the performance benchmarks |
viirya
reviewed
Apr 13, 2023
arrow-json/src/reader/tape.rs
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| /// Return an error containing the [`TapeElement`] at `cur_idx` if it | ||
| /// is not the start of a field |
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Suggested change
| /// Return an error containing the [`TapeElement`] at `cur_idx` if it | |
| /// is not the start of a field | |
| /// Return an error containing at `cur_idx` if it | |
| /// is not the start of a field |
viirya
approved these changes
Apr 13, 2023
viirya
reviewed
Apr 13, 2023
| let err = parse_err(r#"{"a": 123}"#); | ||
| assert_eq!( | ||
| err, | ||
| "Json error: whilst decoding field 'a': expected { got 123" |
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Which issue does this PR close?
Closes #4076
Rationale for this change
This improves the error messages when decoding the tape, these are produced when the JSON input is valid, i.e. has successfully been decoded to a tape, but doesn't match the expected schema. Producing a more helpful error message is therefore useful for identifying what has gone wrong.
Unfortunately at this level rows don't really exist, but at the very least we can provide more context than a single byte 😅
The error messages for invalid JSON are still not brilliant, but given JSON validation is not "specialized", I'm not sure how important this is.
What changes are included in this PR?
Are there any user-facing changes?