Fix: fallback conversion from BibTeX year field to biblatex date field #13040

wanling0000 · 2025-04-30T21:39:54Z

Closes #11868
This PR introduces a fallback mechanism in the "Convert to biblatex" cleanup step to improve compatibility with BibLaTeX-style date formats mistakenly entered in the BibTeX year field.

What was the problem?
Users reported that when year = {2011-11-11} (or other extended formats) is used in BibTeX mode, the "Convert to biblatex" cleanup did not populate the date field as expected.

This is because the cleanup logic only merges year + month if both are present and parsable. Non-standard values in year were silently ignored.

What has been changed?

A fallback step was added after the main conversion logic:
- If date is still missing, and
- year contains a parsable BibLaTeX-style date,
- then date is set directly from year, and year is cleared.

This fallback is intentionally conservative and only runs if the standard cleanup logic does not produce a date.

Mandatory checks

I own the copyright of the code submitted and I license it under the MIT license
Change in CHANGELOG.md described in a way that is understandable for the average user (if change is visible to the user)
Tests created for changes (if applicable)
Manually tested changed features in running JabRef (always required)
[/] Screenshots added in PR description (if change is visible to the user)
Checked developer's documentation: Is the information available and up to date? If not, I outlined it in this pull request.
Checked documentation: Is the information available and up to date? If not, I created an issue at https://github.com/JabRef/user-documentation/issues or, even better, I submitted a pull request to the documentation repository.

…dates in BibTeX `year` field

src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

…dates in BibTeX `year` field

…onvert-to-biblatex

subhramit

Hi, thanks for taking this up.
PR looks good to me, just some nits.

subhramit · 2025-05-01T05:46:04Z

CHANGELOG.md

@@ -15,6 +15,8 @@ Note that this project **does not** adhere to [Semantic Versioning](https://semv

 ### Fixed

+- We fixed an issue where the "Convert to biblatex" cleanup failed to populate the `date` field if `year` contained a full date in ISO format (e.g., `2011-11-11`). A fallback was added to correctly interpret such values. [#11868](https://github.com/JabRef/jabref/issues/11868)


Concise changelog entries are preferred.

Suggested change

- We fixed an issue where the "Convert to biblatex" cleanup failed to populate the `date` field if `year` contained a full date in ISO format (e.g., `2011-11-11`). A fallback was added to correctly interpret such values. [#11868](https://github.com/JabRef/jabref/issues/11868)

- We added a fallback for the "Convert to biblatex" cleanup when it failed to populate the `date` field if `year` contained a full date in ISO format (e.g., `2011-11-11`). [#11868](https://github.com/JabRef/jabref/issues/11868)

subhramit · 2025-05-01T05:51:52Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+        Optional<String> monthValue = entry.getFieldOrAlias(StandardField.MONTH).map(String::trim);
+
+        if (yearValue.isPresent() && monthValue.isEmpty()) {
+            String yearText = yearValue.get().trim();


trim was already used when obtaining yearValue, so this one seems redundant.

…ConvertToBiblatexCleanup

subhramit · 2025-05-01T08:43:26Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+        return changes;
+    }
+
+    private Collection<? extends FieldChange> applyDateFallback(BibEntry entry) {


Oh, another thing -- can we use more specificity here?

Suggested change

private Collection<? extends FieldChange> applyDateFallback(BibEntry entry) {

private List<FieldChange> applyDateFallback(BibEntry entry) {

Or was there a reason you chose Collection<? extends FieldChange>?

(In case you go with this suggestion, remove the unused Collection import too).

My bad! I used IntelliJ’s autocomplete but didn’t pay enough attention to the return type 😭. Will change it to List, thanks!

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

koppor · 2025-05-01T08:28:49Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

@@ -53,6 +54,27 @@ public List<FieldChange> cleanup(BibEntry entry) {
                }
            });
        }
+        // If still no 'date' field, try fallback logic
+        if (entry.getField(StandardField.DATE).isEmpty()) {


Don't we have "hasField"?

Also later instead of trim and is empty maybe just hasField?

The parser should deal with empty strings IMHO

I applied your suggestion to use .hasField for the conditional check, thanks for pointing that out!

However, I kept the trim call inside the method body. I added a test which shows that Date.parse() does not consistently handle trimming of input. While the UI typically strips whitespace automatically, I added this for robustness in case the input comes from other sources.

I'm happy to remove the test if you think it's unnecessary, just let me know!

If we are testing for a negative, I think we should have an assertNotEquals case without the cleanup and an assertEquals after the cleaup.
Along with that, add a comment above the test:

Date.parse() does not consistently handle trimming of input. While the UI typically strips whitespace automatically

To elaborate its purpose

However, I kept the trim call inside the method body. I added a test which shows that Date.parse() does not consistently handle trimming of input

Why not adding trim functionality and tests to the parsing? 😅

…onvert-to-biblatex

trag-bot · 2025-05-02T14:14:32Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+            return changes;
+        }
+
+        entry.setField(StandardField.DATE, yearText).ifPresent(changes::add);


The method setField should use withField for creating a new BibEntry object, as per JabRef's guidelines for creating new objects.

Here, it is OK.

koppor

Some small Java code style nitpicks - just to share knowledge about JabRef's coding conventions. - Hope, this is OK. 😅

koppor · 2025-05-02T22:28:21Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+        Optional<Date> fallbackDate = Date.parse(yearText);
+        if (fallbackDate.isEmpty()) {


I think, the variable fallbackDate is only used at the if -- maybe, inline and say as java comment

// check if yearText is a valid date

koppor · 2025-05-02T22:28:51Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+            return changes;
+        }
+
+        entry.setField(StandardField.DATE, yearText).ifPresent(changes::add);


Add before as java comment:

// If year was a full date, move it from year to date field.

koppor · 2025-05-02T22:29:07Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+    }
+
+    private List<FieldChange> applyDateFallback(BibEntry entry) {
+        List<FieldChange> changes = new ArrayList<>();


I would move that down before line 77

koppor · 2025-05-02T22:29:16Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+
+        Optional<String> yearValue = entry.getFieldOrAlias(StandardField.YEAR).map(String::trim);
+        if (yearValue.isEmpty()) {
+            return changes;


Return List.of()

koppor · 2025-05-02T22:29:21Z

jablib/src/main/java/org/jabref/logic/cleanup/ConvertToBiblatexCleanup.java

+        String yearText = yearValue.get();
+        Optional<Date> fallbackDate = Date.parse(yearText);
+        if (fallbackDate.isEmpty()) {
+            return changes;


Return List.of()

…onvert-to-biblatex

…13040

trag-bot · 2025-05-03T22:25:40Z

jablib/src/test/java/org/jabref/model/entry/DateTest.java

@@ -123,4 +123,13 @@ void parseZonedTime() {
    void parseDateNull() {
        assertThrows(NullPointerException.class, () -> Date.parse(null));
    }
+
+    // Date.parse() has been updated to defensively strip surrounding whitespace from input strings.


The comment is trivial and restates the obvious, which violates the guideline that comments should add new information and not be plainly derived from the code itself.

koppor · 2025-05-04T05:25:22Z

@wanling0000 Thank you for the clean code and the efforts to reach it!

wanling0000 · 2025-05-04T09:15:16Z

@wanling0000 Thank you for the clean code and the efforts to reach it!

Thanks! I’ve actually learned quite a bit from this review, appreciate all the suggestions :)

Add fallback logic to ConvertToBiblatexCleanup for parsing ISO-style …

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…dates in BibTeX `year` field

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wanling0000 added 4 commits April 30, 2025 22:45

Add fallback logic to ConvertToBiblatexCleanup for parsing ISO-style …

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…dates in BibTeX `year` field

Merge remote-tracking branch 'upstream/main' into fix/11868-cleanup-c…

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…onvert-to-biblatex

Add changelog entry

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changelog

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wanling0000 marked this pull request as ready for review April 30, 2025 22:45

test: replace setField with withField

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subhramit reviewed May 1, 2025

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apply suggestions for concise changelog and remove redundant trim in …

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…ConvertToBiblatexCleanup

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use List instead of Collection in applyDateFallback

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subhramit added component: cleanup-ops status: awaiting-second-review For non-trivial changes component: bib(la)tex labels May 1, 2025

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subhramit added status: changes-required Pull requests that are not yet complete and removed status: awaiting-second-review For non-trivial changes labels May 1, 2025

use hasField for date check

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wanling0000 dismissed subhramit’s stale review via b847cd7 May 2, 2025 14:11

Merge remote-tracking branch 'upstream/main' into fix/11868-cleanup-c…

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…onvert-to-biblatex

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wanling0000 added 3 commits May 3, 2025 23:09

Merge remote-tracking branch 'upstream/main' into fix/11868-cleanup-c…

63a0fb2

…onvert-to-biblatex

fix: Trim input in Date.parse and apply style review feedback JabRef#…

e9a03c0

…13040

fix: Trim input in Date.parse and apply style review feedback JabRef#…

e3ad7eb

…13040

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koppor approved these changes May 4, 2025

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Merged via the queue into JabRef:main with commit 99d49ca May 4, 2025
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Cleanup entries - Convert to biblatex does not work #11868

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2 tasks

		@@ -15,6 +15,8 @@ Note that this project does not adhere to [Semantic Versioning](https://semv

		### Fixed

		- We fixed an issue where the "Convert to biblatex" cleanup failed to populate the `date` field if `year` contained a full date in ISO format (e.g., `2011-11-11`). A fallback was added to correctly interpret such values. [#11868](https://github.com/JabRef/jabref/issues/11868)

	- We fixed an issue where the "Convert to biblatex" cleanup failed to populate the `date` field if `year` contained a full date in ISO format (e.g., `2011-11-11`). A fallback was added to correctly interpret such values. [#11868](https://github.com/JabRef/jabref/issues/11868)
	- We added a fallback for the "Convert to biblatex" cleanup when it failed to populate the `date` field if `year` contained a full date in ISO format (e.g., `2011-11-11`). [#11868](https://github.com/JabRef/jabref/issues/11868)

	private Collection<? extends FieldChange> applyDateFallback(BibEntry entry) {
	private List<FieldChange> applyDateFallback(BibEntry entry) {

		Optional<Date> fallbackDate = Date.parse(yearText);
		if (fallbackDate.isEmpty()) {

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Fix: fallback conversion from BibTeX year field to biblatex date field #13040

Fix: fallback conversion from BibTeX year field to biblatex date field #13040

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