Add null-handling for transaction linking and update tests

Introduced null checks in `LinkTransactionHandler` to handle cases where labels or names are unset during transaction linking. Added a new test case `handleRelationEvent_unset` and updated SQL scripts to include relevant scenarios for better coverage. Ensures robust handling of nullable inputs in transaction-related workflows.

Author: gjong

jpa-repository/src/main/java/com/jongsoft/finance/jpa/transaction/LinkTransactionHandler.java

@@ -58,6 +58,9 @@ private EntityJpa fetchRelation(LinkTransactionCommand.LinkType type, String rel
     }
 
     private CategoryJpa category(String label) {
+        if (label == null) {
+            return null;
+        }
         return entityManager.from(CategoryJpa.class)
                 .fieldEq("user.username", authenticationFacade.authenticated())
                 .fieldEq("label", label)
@@ -66,6 +69,9 @@ private CategoryJpa category(String label) {
     }
 
     private ExpenseJpa expense(String name) {
+        if (name == null) {
+            return null;
+        }
         return entityManager.from(ExpenseJpa.class)
                 .fieldEq("name", name)
                 .fieldEq("user.username", authenticationFacade.authenticated())
@@ -74,6 +80,9 @@ private ExpenseJpa expense(String name) {
     }
 
     private ContractJpa contract(String name) {
+        if (name == null) {
+            return null;
+        }
         return entityManager.from(ContractJpa.class)
                 .fieldEq("name", name)
                 .fieldEq("user.username", authenticationFacade.authenticated())

jpa-repository/src/test/java/com/jongsoft/finance/jpa/transaction/TransactionEventListenerIT.java

@@ -17,7 +17,6 @@
 import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
 
-import java.io.Serializable;
 import java.math.BigDecimal;
 import java.time.LocalDate;
 import java.util.Objects;
@@ -131,6 +130,16 @@ void handleRelationEvent_category() {
         Assertions.assertThat(check.getCategory().getLabel()).isEqualTo("Test");
     }
 
+    @Test
+    void handleRelationEvent_unset() {
+        eventPublisher.publishEvent(new LinkTransactionCommand(
+                3L,
+                LinkTransactionCommand.LinkType.CATEGORY,
+                null));
+        var check = entityManager.find(TransactionJournal.class, 3L);
+        Assertions.assertThat(check.getCategory()).isNull();
+    }
+
     @Test
     void handleTagEvent() {
         eventPublisher.publishEvent(new TagTransactionCommand(

jpa-repository/src/test/resources/sql/transaction/transaction-provider.sql

@@ -4,26 +4,31 @@ values (1, 1, 'Account One', 'Demo Account', 1, false, 1, 'NLJND200001928233', '
        (3, 1, 'Split account 1', null, 1, false, 1, '', '', ''),
        (4, 1, 'Split account 2', null, 1, false, 7, '', '', '');
 
+insert into category (id, label, user_id, archived)
+values (1, 'Grocery', 1, false),
+       (2, 'Test', 1, false);
+
+insert into tags (id, name, user_id, archived)
+values (1, 'Sample 1', 1, 0),
+       (2, 'Food', 1, 0),
+       (3, 'Drugs', 1, 0);
+
 insert into transaction_journal (ID, created, updated, T_DATE, DESCRIPTION, currency_id, TYPE, USER_ID)
 values (1, '2019-01-01', '2019-01-01', '2019-01-01', 'Sample transaction', 1, 'CREDIT', 1),
        (2, '2019-01-02', '2019-01-02', '2019-01-02', 'Split transaction sample', 1, 'CREDIT', 1);
 
+insert into transaction_journal (ID, created, updated, T_DATE, DESCRIPTION, currency_id, TYPE, USER_ID, CATEGORY_ID)
+values (3, '2019-01-01', '2019-01-01', '2019-01-01', 'Categorized transaction', 1, 'CREDIT', 1, 1);
+
 insert into transaction_part (ID, created, updated, deleted, JOURNAL_ID, ACCOUNT_ID, AMOUNT)
 values (1, '2019-01-01', '2019-01-01', null, 1, 1, 20.2),
        (2, '2019-01-01', '2019-01-01', null, 1, 2, -20.2),
        (3, '2019-01-02', '2019-01-01', null, 2, 3, 20.2),
        (4, '2019-01-02', '2019-01-05', '2019-01-05', 2, 4, -20.2),
        (5, '2019-01-05', '2019-01-05', null, 2, 4, -10.2),
-       (6, '2019-01-05', '2019-01-05', null, 2, 4, -10.0);
-
-insert into category (id, label, user_id, archived)
-values (1, 'Grocery', 1, false),
-       (2, 'Test', 1, false);
-
-insert into tags (id, name, user_id, archived)
-values (1, 'Sample 1', 1, 0),
-       (2, 'Food', 1, 0),
-       (3, 'Drugs', 1, 0);
+       (6, '2019-01-05', '2019-01-05', null, 2, 4, -10.0),
+       (7, '2019-01-05', '2019-01-05', null, 3, 4, -10.2),
+       (8, '2019-01-05', '2019-01-05', null, 3, 4, -10.0);
 
 insert into transaction_tag (tag_id, transaction_id)
 values (1, 1),