feat: Improve entity join handling with enhanced column validation and support for complex keys

- Updated the entityJoinService to include type casting for source and reference columns, ensuring compatibility during joins.
- Implemented validation for reference columns in the TableManagementService, allowing automatic fallback to 'id' if the specified reference column does not exist.
- Enhanced logging for join configurations to provide better insights during the join setup process.
- Transitioned the SplitPanelLayoutComponent to utilize the entityJoinApi for handling single key to composite key transformations, improving data retrieval efficiency.
- Added support for displaying null or empty values as "-" in the SplitPanelLayout, enhancing user experience.

backend-node/src/services/tableManagementService.ts

@@ -2979,31 +2979,49 @@ export class TableManagementService {
               continue; // 기본 Entity 조인과 중복되면 추가하지 않음
             }
 
-            // 추가 조인 컬럼 설정 생성
-            const additionalJoinConfig: EntityJoinConfig = {
-              sourceTable: tableName,
-              sourceColumn: sourceColumn, // 실제 소스 컬럼 (partner_id)
-              referenceTable:
-                (additionalColumn as any).referenceTable ||
-                baseJoinConfig.referenceTable, // 참조 테이블 (customer_mng)
-              referenceColumn: baseJoinConfig.referenceColumn, // 참조 키 (customer_code)
-              displayColumns: [actualColumnName], // 표시할 컬럼들 (customer_name)
-              displayColumn: actualColumnName, // 하위 호환성
-              aliasColumn: correctedJoinAlias, // 수정된 별칭 (partner_id_customer_name)
-              separator: " - ", // 기본 구분자
-            };
-
-            joinConfigs.push(additionalJoinConfig);
-            logger.info(
-              `✅ 추가 조인 컬럼 설정 추가: ${additionalJoinConfig.aliasColumn} -> ${actualColumnName}`
+            // 🆕 같은 sourceColumn + referenceTable 조합의 기존 config가 있으면 displayColumns에 병합
+            const existingConfig = joinConfigs.find(
+              (config) =>
+                config.sourceColumn === sourceColumn &&
+                config.referenceTable === ((additionalColumn as any).referenceTable || baseJoinConfig.referenceTable)
             );
-            logger.info(`🔍 추가된 조인 설정 상세:`, {
-              sourceTable: additionalJoinConfig.sourceTable,
-              sourceColumn: additionalJoinConfig.sourceColumn,
-              referenceTable: additionalJoinConfig.referenceTable,
-              displayColumns: additionalJoinConfig.displayColumns,
-              aliasColumn: additionalJoinConfig.aliasColumn,
-            });
+
+            if (existingConfig) {
+              // 기존 config에 display column 추가 (중복 방지)
+              if (!existingConfig.displayColumns?.includes(actualColumnName)) {
+                existingConfig.displayColumns = existingConfig.displayColumns || [];
+                existingConfig.displayColumns.push(actualColumnName);
+                logger.info(
+                  `🔄 기존 조인 설정에 컬럼 병합: ${existingConfig.aliasColumn} ← ${actualColumnName} (총 ${existingConfig.displayColumns.length}개)`
+                );
+              }
+            } else {
+              // 새 조인 설정 생성
+              const additionalJoinConfig: EntityJoinConfig = {
+                sourceTable: tableName,
+                sourceColumn: sourceColumn, // 실제 소스 컬럼 (partner_id)
+                referenceTable:
+                  (additionalColumn as any).referenceTable ||
+                  baseJoinConfig.referenceTable, // 참조 테이블 (customer_mng)
+                referenceColumn: baseJoinConfig.referenceColumn, // 참조 키 (customer_code)
+                displayColumns: [actualColumnName], // 표시할 컬럼들 (customer_name)
+                displayColumn: actualColumnName, // 하위 호환성
+                aliasColumn: correctedJoinAlias, // 수정된 별칭 (partner_id_customer_name)
+                separator: " - ", // 기본 구분자
+              };
+
+              joinConfigs.push(additionalJoinConfig);
+              logger.info(
+                `✅ 추가 조인 컬럼 설정 추가: ${additionalJoinConfig.aliasColumn} -> ${actualColumnName}`
+              );
+              logger.info(`🔍 추가된 조인 설정 상세:`, {
+                sourceTable: additionalJoinConfig.sourceTable,
+                sourceColumn: additionalJoinConfig.sourceColumn,
+                referenceTable: additionalJoinConfig.referenceTable,
+                displayColumns: additionalJoinConfig.displayColumns,
+                aliasColumn: additionalJoinConfig.aliasColumn,
+              });
+            }
           }
         }
       }