Add check for existing crossrefs when importing entries into a library

CHANGELOG.md

@@ -87,6 +87,7 @@ Note that this project **does not** adhere to [Semantic Versioning](https://semv
 - We fixed an issue where the Undo/Redo buttons were active even when all libraries are closed. [#11837](https://github.com/JabRef/jabref/issues/11837)
 - We fixed an issue where recently opened files were not displayed in the main menu properly. [#9042](https://github.com/JabRef/jabref/issues/9042)
 - We fixed an issue where the DOI lookup would show an error when a DOI was found for an entry. [#11850](https://github.com/JabRef/jabref/issues/11850)
+- We fixed an issue where adding a crossreferenced entry would not correctly generate a citation key for the child entry [#11136](https://github.com/JabRef/jabref/issues/11136)
 
 ### Removed
 

src/main/java/org/jabref/gui/externalfiles/ImportHandler.java

@@ -303,6 +303,25 @@ private void addToGroups(List<BibEntry> entries, Collection<GroupTreeNode> group
         }
     }
 
+    public void checkCrossRefKeys(List<BibEntry> entries) {
+        for (BibEntry possibleParentEntry : entries) {
+            for (BibEntry entry : bibDatabaseContext.getDatabase().getEntries()) {
+                Optional<String> crossRef = entry.getField(StandardField.CROSSREF);
+                Optional<String> childYear = entry.getField(StandardField.YEAR);
+                Optional<String> parentKey = possibleParentEntry.getCitationKey();
+                if (crossRef.isPresent() && crossRef.equals(parentKey) && !childYear.isPresent()) {
+                    Optional<String> parentYear = possibleParentEntry.getField(StandardField.YEAR);
+                    parentYear.ifPresent(year -> {
+                        String existingKey = entry.getCitationKey().orElse("");
+                        String newKey = existingKey+year;
+                        // retroactively set citation key to match parent's year
+                        entry.setCitationKey(newKey);
+                    });
+                }
+            }
+        }
+    }
+
     /**
      * Generate keys for given entries.
      *
@@ -318,6 +337,7 @@ private void generateKeys(List<BibEntry> entries) {
                 bibDatabaseContext.getDatabase(),
                 preferences.getCitationKeyPatternPreferences());
         entries.forEach(keyGenerator::generateAndSetKey);
+        checkCrossRefKeys(entries);
     }
 
     public List<BibEntry> handleBibTeXData(String entries) {

src/test/java/org/jabref/gui/externalfiles/ImportHandlerTest.java

@@ -14,6 +14,7 @@
 import org.jabref.logic.bibtex.FieldPreferences;
 import org.jabref.logic.database.DuplicateCheck;
 import org.jabref.logic.importer.ImportFormatPreferences;
+import org.jabref.logic.importer.ImporterPreferences;
 import org.jabref.logic.util.CurrentThreadTaskExecutor;
 import org.jabref.model.database.BibDatabase;
 import org.jabref.model.database.BibDatabaseContext;
@@ -223,4 +224,28 @@ void handleDuplicatesKeepMergeTest() {
         assertFalse(bibDatabase.getEntries().contains(duplicateEntry)); // Assert that the duplicate entry was removed from the database
         assertEquals(mergedEntry, result); // Assert that the merged entry is returned
     }
+
+    @Test
+    void testCheckCrossRefKeys() {
+        BibDatabase bibDatabase = bibDatabaseContext.getDatabase();
+
+        BibEntry childEntry = new BibEntry();
+        childEntry.setField(StandardField.CROSSREF, "ParentKey");
+        childEntry.setCitationKey("ChildKey");
+
+        bibDatabase.insertEntry(childEntry);
+
+        assertEquals("ChildKey", childEntry.getCitationKey().orElse(""));
+
+        BibEntry parentEntry = new BibEntry();
+        parentEntry.setCitationKey("ParentKey");
+        parentEntry.setField(StandardField.YEAR, "2021");
+
+        bibDatabase.insertEntry(parentEntry);
+
+        importHandler.checkCrossRefKeys(List.of(parentEntry));
+
+        // The child entry's citation key should now be updated with the parent's year
+        assertEquals("ChildKey2021", childEntry.getCitationKey().orElse(""));
+    }
 }