Feat[BE]: refactor document handling in transfer service and introduce document type constants

internal/modules/inventory/transfers/services/transfer.service.go

@@ -76,8 +76,8 @@ func (s transferService) withRelations(db *gorm.DB) *gorm.DB {
 		Preload("Details.Product").
 		Preload("Deliveries.Items").
 		Preload("Deliveries.Supplier").
-		Preload("Documents", func(db *gorm.DB) *gorm.DB {
-			return db.Where("documentable_type = ?", "STOCK_TRANSFER")
+		Preload("Deliveries.Documents", func(db *gorm.DB) *gorm.DB {
+			return db.Where("documentable_type = ?", string(utils.DocumentableTypeTransfer))
 		})
 }
 
@@ -258,29 +258,26 @@ func (s *transferService) CreateOne(c *fiber.Ctx, req *validation.TransferReques
 			return err
 		}
 
-		actorIDCopy := actorID
 		if s.DocumentSvc != nil && len(files) > 0 {
-			s.Log.Infof("Starting document upload for %d files", len(files))
-			documentFiles := make([]commonSvc.DocumentFile, 0, len(files))
+			// Upload documents for each delivery
 			for idx, file := range files {
-				docIndex := idx
-				documentFiles = append(documentFiles, commonSvc.DocumentFile{
-					File:  file,
-					Type:  "STOCK_TRANSFER_DOCUMENT",
-					Index: &docIndex,
+				documentFiles := []commonSvc.DocumentFile{
+					{
+						File:  file,
+						Type:  string(utils.DocumentTypeTransfer),
+						Index: &idx,
+					},
+				}
+				_, err := s.DocumentSvc.UploadDocuments(c.Context(), commonSvc.DocumentUploadRequest{
+					DocumentableType: string(utils.DocumentableTypeTransfer),
+					DocumentableID:   deliveries[idx].Id,
+					CreatedBy:        &actorID,
+					Files:            documentFiles,
 				})
+				if err != nil {
+					return fiber.NewError(fiber.StatusInternalServerError, fmt.Sprintf("Failed to upload document for delivery %d", idx+1))
+				}
 			}
-			_, err := s.DocumentSvc.UploadDocuments(c.Context(), commonSvc.DocumentUploadRequest{
-				DocumentableType: "STOCK_TRANSFER",
-				DocumentableID:   entityTransfer.Id,
-				CreatedBy:        &actorIDCopy,
-				Files:            documentFiles,
-			})
-			if err != nil {
-				s.Log.Errorf("Failed to upload documents for transfer %d: %+v", entityTransfer.Id, err)
-				return fiber.NewError(fiber.StatusInternalServerError, "Failed to upload transfer documents")
-			}
-			s.Log.Infof("Successfully uploaded documents for transfer ID %d", entityTransfer.Id)
 		}
 
 		for _, product := range req.Products {