Fix handling of "null" values for non-TEXT columns in CSV imports

[inv-jishnu]

Description

This PR updates the column creation logic in createColumnFromValue() in the ColumnUtils class to correctly interpret the string "null" as an actual null value for non-TEXT column types.

Previously, when a CSV file contained null as a value, it was parsed as the literal string "null", causing the initial null check (value != null) to behave differently than when the same value was provided via JSON or JSON Lines. As a result, CSV-based imports failed, while JSON and JSON Lines imports handled null values correctly.

This fix ensures consistent behavior across all file types by converting "null" to a real null value for all column types except TEXT when provided via a CSV file.

Related issues and/or PRs

NA

Changes made

• Updated createColumnFromValue() method in ColumnUtils class and added a pre-check:

• Added Unit Tests in ColumnUtilsTest

Checklist

The following is a best-effort checklist. If any items in this checklist are not applicable to this PR or are dependent on other, unmerged PRs, please still mark the checkboxes after you have read and understood each item.

• I have commented my code, particularly in hard-to-understand areas.
• I have updated the documentation to reflect the changes.
• I have considered whether similar issues could occur in other products, components, or modules if this PR is for bug fixes.
• Any remaining open issues linked to this PR are documented and up-to-date (Jira, GitHub, etc.).
• Tests (unit, integration, etc.) have been added for the changes.
• My changes generate no new warnings.
• Any dependent changes in other PRs have been merged and published.

Additional notes (optional)

NA

Release notes

Fixed handling of "null" values for non-TEXT columns in CSV imports

[gemini-code-assist]

Summary of Changes

Hello @inv-jishnu, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request standardizes the handling of "null" values across different data import formats. Previously, CSV imports treated the string "null" as a literal for non-TEXT columns, causing inconsistencies and potential failures compared to JSON and JSONLines. The changes modify the createColumnFromValue method to correctly convert the string "null" into a true null value for all non-TEXT data types, ensuring uniform data interpretation and improving the robustness of data loading processes.

Highlights

• Consistent Null Handling: The pull request introduces a change to correctly interpret the string "null" as an actual null value for non-TEXT column types during CSV imports, aligning its behavior with JSON and JSONLines imports.
• CSV Import Reliability: This fix resolves issues where CSV-based imports would fail due to the string "null" being incorrectly parsed as a literal string instead of a null value for non-TEXT fields.
• Enhanced Test Coverage: New unit tests have been added to ColumnUtilsTest to ensure the correct handling of "null" strings for various data types, including specific tests for non-TEXT types being converted to null and TEXT types retaining "null" as a literal string.

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[gemini-code-assist]

Code Review

This pull request correctly handles string "null" values from CSV imports as null for non-TEXT columns, aligning behavior with other file formats. The implementation is sound, and new unit tests validate the change. My main feedback is to make the "null" string check case-insensitive (e.g., to handle "NULL" and "Null") for better robustness, and to update the corresponding unit tests to cover these cases. This will make the feature more user-friendly.

[ypeckstadt]

LGTM. Thank you.

[brfrn169]

LGTM! Thank you!

[komamitsu]

LGTM! 👍

[feeblefakie]

LGTM! Thank you!

[Torch3333]

LGTM, thank you!

[thongdk8]

LGTM! Thank you!