Fixes for CUD operations

pkg/reflection/model_utils.go

@@ -45,6 +45,62 @@ func GetPrimaryKeyName(model any) string {
 	return ""
 }
 
+// GetPrimaryKeyValue extracts the primary key value from a model instance
+// Returns the value of the primary key field
+func GetPrimaryKeyValue(model any) interface{} {
+	if model == nil || reflect.TypeOf(model) == nil {
+		return nil
+	}
+
+	val := reflect.ValueOf(model)
+	if val.Kind() == reflect.Pointer {
+		val = val.Elem()
+	}
+
+	if val.Kind() != reflect.Struct {
+		return nil
+	}
+
+	typ := val.Type()
+
+	// Try Bun tag first
+	for i := 0; i < typ.NumField(); i++ {
+		field := typ.Field(i)
+		bunTag := field.Tag.Get("bun")
+		if strings.Contains(bunTag, "pk") {
+			fieldValue := val.Field(i)
+			if fieldValue.CanInterface() {
+				return fieldValue.Interface()
+			}
+		}
+	}
+
+	// Fall back to GORM tag
+	for i := 0; i < typ.NumField(); i++ {
+		field := typ.Field(i)
+		gormTag := field.Tag.Get("gorm")
+		if strings.Contains(gormTag, "primaryKey") {
+			fieldValue := val.Field(i)
+			if fieldValue.CanInterface() {
+				return fieldValue.Interface()
+			}
+		}
+	}
+
+	// Last resort: look for field named "ID" or "Id"
+	for i := 0; i < typ.NumField(); i++ {
+		field := typ.Field(i)
+		if strings.ToLower(field.Name) == "id" {
+			fieldValue := val.Field(i)
+			if fieldValue.CanInterface() {
+				return fieldValue.Interface()
+			}
+		}
+	}
+
+	return nil
+}
+
 // GetModelColumns extracts all column names from a model using reflection
 // It checks bun tags first, then gorm tags, then json tags, and finally falls back to lowercase field names
 func GetModelColumns(model any) []string {

pkg/restheadspec/handler.go

@@ -584,22 +584,6 @@ func (h *Handler) handleCreate(ctx context.Context, w common.ResponseWriter, dat
 
 	logger.Info("Creating record in %s.%s", schema, entity)
 
-	// Check if data is a single map with nested relations
-	if dataMap, ok := data.(map[string]interface{}); ok {
-		if h.shouldUseNestedProcessor(dataMap, model) {
-			logger.Info("Using nested CUD processor for create operation")
-			result, err := h.nestedProcessor.ProcessNestedCUD(ctx, "insert", dataMap, model, make(map[string]interface{}), tableName)
-			if err != nil {
-				logger.Error("Error in nested create: %v", err)
-				h.sendError(w, http.StatusInternalServerError, "create_error", "Error creating record with nested data", err)
-				return
-			}
-			logger.Info("Successfully created record with nested data, ID: %v", result.ID)
-			h.sendResponseWithOptions(w, result.Data, nil, &options)
-			return
-		}
-	}
-
 	// Execute BeforeCreate hooks
 	hookCtx := &HookContext{
 		Context:   ctx,
@@ -622,87 +606,57 @@ func (h *Handler) handleCreate(ctx context.Context, w common.ResponseWriter, dat
 	// Use potentially modified data from hook context
 	data = hookCtx.Data
 
-	// Handle batch creation
-	dataValue := reflect.ValueOf(data)
-	if dataValue.Kind() == reflect.Slice || dataValue.Kind() == reflect.Array {
-		logger.Debug("Batch creation detected, count: %d", dataValue.Len())
+	// Normalize data to slice for unified processing
+	dataSlice := h.normalizeToSlice(data)
+	logger.Debug("Processing %d item(s) for creation", len(dataSlice))
 
-		// Check if any item needs nested processing
-		hasNestedData := false
-		for i := 0; i < dataValue.Len(); i++ {
-			item := dataValue.Index(i).Interface()
-			if itemMap, ok := item.(map[string]interface{}); ok {
+	// Process all items in a transaction
+	results := make([]interface{}, 0, len(dataSlice))
+	err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
+		// Create temporary nested processor with transaction
+		txNestedProcessor := common.NewNestedCUDProcessor(tx, h.registry, h)
+
+		for i, item := range dataSlice {
+			itemMap, ok := item.(map[string]interface{})
+			if !ok {
+				// Convert to map if needed
+				jsonData, err := json.Marshal(item)
+				if err != nil {
+					return fmt.Errorf("failed to marshal item %d: %w", i, err)
+				}
+				itemMap = make(map[string]interface{})
+				if err := json.Unmarshal(jsonData, &itemMap); err != nil {
+					return fmt.Errorf("failed to unmarshal item %d: %w", i, err)
+				}
+			}
+
+			// Extract nested relations if present (but don't process them yet)
+			var nestedRelations map[string]interface{}
 			if h.shouldUseNestedProcessor(itemMap, model) {
-					hasNestedData = true
-					break
-				}
-			}
-		}
-
-		if hasNestedData {
-			logger.Info("Using nested CUD processor for batch create with nested data")
-			results := make([]interface{}, 0, dataValue.Len())
-			err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
-				// Temporarily swap the database to use transaction
-				originalDB := h.nestedProcessor
-				h.nestedProcessor = common.NewNestedCUDProcessor(tx, h.registry, h)
-				defer func() {
-					h.nestedProcessor = originalDB
-				}()
-
-				for i := 0; i < dataValue.Len(); i++ {
-					item := dataValue.Index(i).Interface()
-					if itemMap, ok := item.(map[string]interface{}); ok {
-						result, err := h.nestedProcessor.ProcessNestedCUD(ctx, "insert", itemMap, model, make(map[string]interface{}), tableName)
+				logger.Debug("Extracting nested relations for item %d", i)
+				cleanedData, relations, err := h.extractNestedRelations(itemMap, model)
 				if err != nil {
-							return fmt.Errorf("failed to process item: %w", err)
+					return fmt.Errorf("failed to extract nested relations for item %d: %w", i, err)
 				}
-						results = append(results, result.Data)
+				itemMap = cleanedData
+				nestedRelations = relations
 			}
-				}
-				return nil
-			})
-			if err != nil {
-				logger.Error("Error creating records with nested data: %v", err)
-				h.sendError(w, http.StatusInternalServerError, "create_error", "Error creating records with nested data", err)
-				return
-			}
-
-			// Execute AfterCreate hooks
-			hookCtx.Result = map[string]interface{}{"created": len(results), "data": results}
-			hookCtx.Error = nil
-
-			if err := h.hooks.Execute(AfterCreate, hookCtx); err != nil {
-				logger.Error("AfterCreate hook failed: %v", err)
-				h.sendError(w, http.StatusInternalServerError, "hook_error", "Hook execution failed", err)
-				return
-			}
-
-			logger.Info("Successfully created %d records with nested data", len(results))
-			h.sendResponseWithOptions(w, results, nil, &options)
-			return
-		}
-
-		// Standard batch insert without nested relations
-		// Use transaction for batch insert
-		err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
-			for i := 0; i < dataValue.Len(); i++ {
-				item := dataValue.Index(i).Interface()
 
 			// Convert item to model type - create a pointer to the model
 			modelValue := reflect.New(reflect.TypeOf(model)).Interface()
-				jsonData, err := json.Marshal(item)
+			jsonData, err := json.Marshal(itemMap)
 			if err != nil {
-					return fmt.Errorf("failed to marshal item: %w", err)
+				return fmt.Errorf("failed to marshal item %d: %w", i, err)
 			}
 			if err := json.Unmarshal(jsonData, modelValue); err != nil {
-					return fmt.Errorf("failed to unmarshal item: %w", err)
+				return fmt.Errorf("failed to unmarshal item %d: %w", i, err)
 			}
 
-				query := tx.NewInsert().Model(modelValue).Table(tableName)
+			// Create insert query
+			query := tx.NewInsert().Model(modelValue).Table(tableName).Returning("*")
 
 			// Execute BeforeScan hooks - pass query chain so hooks can modify it
-				batchHookCtx := &HookContext{
+			itemHookCtx := &HookContext{
 				Context:   ctx,
 				Handler:   h,
 				Schema:    schema,
@@ -714,18 +668,32 @@ func (h *Handler) handleCreate(ctx context.Context, w common.ResponseWriter, dat
 				Writer:    w,
 				Query:     query,
 			}
-				if err := h.hooks.Execute(BeforeScan, batchHookCtx); err != nil {
-					return fmt.Errorf("BeforeScan hook failed: %w", err)
+			if err := h.hooks.Execute(BeforeScan, itemHookCtx); err != nil {
+				return fmt.Errorf("BeforeScan hook failed for item %d: %w", i, err)
 			}
 
 			// Use potentially modified query from hook context
-				if modifiedQuery, ok := batchHookCtx.Query.(common.InsertQuery); ok {
+			if modifiedQuery, ok := itemHookCtx.Query.(common.InsertQuery); ok {
 				query = modifiedQuery
 			}
 
+			// Execute insert and get the ID
 			if _, err := query.Exec(ctx); err != nil {
-					return fmt.Errorf("failed to insert record: %w", err)
+				return fmt.Errorf("failed to insert item %d: %w", i, err)
 			}
+
+			// Get the inserted ID
+			insertedID := reflection.GetPrimaryKeyValue(modelValue)
+
+			// Now process nested relations with the parent ID
+			if len(nestedRelations) > 0 {
+				logger.Debug("Processing nested relations for item %d with parent ID: %v", i, insertedID)
+				if err := h.processChildRelationsWithParentID(ctx, txNestedProcessor, "insert", nestedRelations, model, insertedID); err != nil {
+					return fmt.Errorf("failed to process nested relations for item %d: %w", i, err)
+				}
+			}
+
+			results = append(results, modelValue)
 		}
 		return nil
 	})
@@ -736,8 +704,15 @@ func (h *Handler) handleCreate(ctx context.Context, w common.ResponseWriter, dat
 		return
 	}
 
-		// Execute AfterCreate hooks for batch creation
-		hookCtx.Result = map[string]interface{}{"created": dataValue.Len()}
+	// Execute AfterCreate hooks
+	var responseData interface{}
+	if len(results) == 1 {
+		responseData = results[0]
+		hookCtx.Result = results[0]
+	} else {
+		responseData = results
+		hookCtx.Result = map[string]interface{}{"created": len(results), "data": results}
+	}
 	hookCtx.Error = nil
 
 	if err := h.hooks.Execute(AfterCreate, hookCtx); err != nil {
@@ -746,57 +721,8 @@ func (h *Handler) handleCreate(ctx context.Context, w common.ResponseWriter, dat
 		return
 	}
 
-		h.sendResponse(w, map[string]interface{}{"created": dataValue.Len()}, nil)
-		return
-	}
-
-	// Single record creation - create a pointer to the model
-	modelValue := reflect.New(reflect.TypeOf(model)).Interface()
-	jsonData, err := json.Marshal(data)
-	if err != nil {
-		logger.Error("Error marshaling data: %v", err)
-		h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
-		return
-	}
-	if err := json.Unmarshal(jsonData, modelValue); err != nil {
-		logger.Error("Error unmarshaling data: %v", err)
-		h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
-		return
-	}
-
-	query := h.db.NewInsert().Model(modelValue).Table(tableName)
-
-	// Execute BeforeScan hooks - pass query chain so hooks can modify it
-	hookCtx.Data = modelValue
-	hookCtx.Query = query
-	if err := h.hooks.Execute(BeforeScan, hookCtx); err != nil {
-		logger.Error("BeforeScan hook failed: %v", err)
-		h.sendError(w, http.StatusBadRequest, "hook_error", "Hook execution failed", err)
-		return
-	}
-
-	// Use potentially modified query from hook context
-	if modifiedQuery, ok := hookCtx.Query.(common.InsertQuery); ok {
-		query = modifiedQuery
-	}
-
-	if _, err := query.Exec(ctx); err != nil {
-		logger.Error("Error creating record: %v", err)
-		h.sendError(w, http.StatusInternalServerError, "create_error", "Error creating record", err)
-		return
-	}
-
-	// Execute AfterCreate hooks for single record creation
-	hookCtx.Result = modelValue
-	hookCtx.Error = nil
-
-	if err := h.hooks.Execute(AfterCreate, hookCtx); err != nil {
-		logger.Error("AfterCreate hook failed: %v", err)
-		h.sendError(w, http.StatusInternalServerError, "hook_error", "Hook execution failed", err)
-		return
-	}
-
-	h.sendResponseWithOptions(w, modelValue, nil, &options)
+	logger.Info("Successfully created %d record(s)", len(results))
+	h.sendResponseWithOptions(w, responseData, nil, &options)
 }
 
 func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id string, idPtr *int64, data interface{}, options ExtendedRequestOptions) {
@@ -814,46 +740,6 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 
 	logger.Info("Updating record in %s.%s", schema, entity)
 
-	// Convert data to map first for nested processor check
-	dataMap, ok := data.(map[string]interface{})
-	if !ok {
-		jsonData, err := json.Marshal(data)
-		if err != nil {
-			logger.Error("Error marshaling data: %v", err)
-			h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
-			return
-		}
-		if err := json.Unmarshal(jsonData, &dataMap); err != nil {
-			logger.Error("Error unmarshaling data: %v", err)
-			h.sendError(w, http.StatusBadRequest, "invalid_data", "Invalid data format", err)
-			return
-		}
-	}
-
-	// Check if we should use nested processing
-	if h.shouldUseNestedProcessor(dataMap, model) {
-		logger.Info("Using nested CUD processor for update operation")
-		// Ensure ID is in the data map
-		var targetID interface{}
-		if id != "" {
-			targetID = id
-		} else if idPtr != nil {
-			targetID = *idPtr
-		}
-		if targetID != nil {
-			dataMap["id"] = targetID
-		}
-		result, err := h.nestedProcessor.ProcessNestedCUD(ctx, "update", dataMap, model, make(map[string]interface{}), tableName)
-		if err != nil {
-			logger.Error("Error in nested update: %v", err)
-			h.sendError(w, http.StatusInternalServerError, "update_error", "Error updating record with nested data", err)
-			return
-		}
-		logger.Info("Successfully updated record with nested data, rows: %d", result.AffectedRows)
-		h.sendResponseWithOptions(w, result.Data, nil, &options)
-		return
-	}
-
 	// Execute BeforeUpdate hooks
 	hookCtx := &HookContext{
 		Context:   ctx,
@@ -877,8 +763,8 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 	// Use potentially modified data from hook context
 	data = hookCtx.Data
 
-	// Convert data to map (again if modified by hooks)
-	dataMap, ok = data.(map[string]interface{})
+	// Convert data to map
+	dataMap, ok := data.(map[string]interface{})
 	if !ok {
 		jsonData, err := json.Marshal(data)
 		if err != nil {
@@ -893,25 +779,46 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 		}
 	}
 
-	query := h.db.NewUpdate().Table(tableName).SetMap(dataMap)
-	pkName := reflection.GetPrimaryKeyName(model)
-	// Apply ID filter
-	switch {
-	case id != "":
-		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(pkName)), id)
-	case idPtr != nil:
-		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(pkName)), *idPtr)
-	default:
+	// Determine target ID
+	var targetID interface{}
+	if id != "" {
+		targetID = id
+	} else if idPtr != nil {
+		targetID = *idPtr
+	} else {
 		h.sendError(w, http.StatusBadRequest, "missing_id", "ID is required for update", nil)
 		return
 	}
 
+	// Process nested relations if present
+	err := h.db.RunInTransaction(ctx, func(tx common.Database) error {
+		// Create temporary nested processor with transaction
+		txNestedProcessor := common.NewNestedCUDProcessor(tx, h.registry, h)
+
+		// Extract nested relations if present (but don't process them yet)
+		var nestedRelations map[string]interface{}
+		if h.shouldUseNestedProcessor(dataMap, model) {
+			logger.Debug("Extracting nested relations for update")
+			cleanedData, relations, err := h.extractNestedRelations(dataMap, model)
+			if err != nil {
+				return fmt.Errorf("failed to extract nested relations: %w", err)
+			}
+			dataMap = cleanedData
+			nestedRelations = relations
+		}
+
+		// Ensure ID is in the data map for the update
+		dataMap["id"] = targetID
+
+		// Create update query
+		query := tx.NewUpdate().Table(tableName).SetMap(dataMap)
+		pkName := reflection.GetPrimaryKeyName(model)
+		query = query.Where(fmt.Sprintf("%s = ?", common.QuoteIdent(pkName)), targetID)
+
 		// Execute BeforeScan hooks - pass query chain so hooks can modify it
 		hookCtx.Query = query
 		if err := h.hooks.Execute(BeforeScan, hookCtx); err != nil {
-		logger.Error("BeforeScan hook failed: %v", err)
-		h.sendError(w, http.StatusBadRequest, "hook_error", "Hook execution failed", err)
-		return
+			return fmt.Errorf("BeforeScan hook failed: %w", err)
 		}
 
 		// Use potentially modified query from hook context
@@ -919,7 +826,27 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 			query = modifiedQuery
 		}
 
+		// Execute update
 		result, err := query.Exec(ctx)
+		if err != nil {
+			return fmt.Errorf("failed to update record: %w", err)
+		}
+
+		// Now process nested relations with the parent ID
+		if len(nestedRelations) > 0 {
+			logger.Debug("Processing nested relations for update with parent ID: %v", targetID)
+			if err := h.processChildRelationsWithParentID(ctx, txNestedProcessor, "update", nestedRelations, model, targetID); err != nil {
+				return fmt.Errorf("failed to process nested relations: %w", err)
+			}
+		}
+
+		// Store result for hooks
+		hookCtx.Result = map[string]interface{}{
+			"updated": result.RowsAffected(),
+		}
+		return nil
+	})
+
 	if err != nil {
 		logger.Error("Error updating record: %v", err)
 		h.sendError(w, http.StatusInternalServerError, "update_error", "Error updating record", err)
@@ -927,19 +854,15 @@ func (h *Handler) handleUpdate(ctx context.Context, w common.ResponseWriter, id
 	}
 
 	// Execute AfterUpdate hooks
-	responseData := map[string]interface{}{
-		"updated": result.RowsAffected(),
-	}
-	hookCtx.Result = responseData
 	hookCtx.Error = nil
-
 	if err := h.hooks.Execute(AfterUpdate, hookCtx); err != nil {
 		logger.Error("AfterUpdate hook failed: %v", err)
 		h.sendError(w, http.StatusInternalServerError, "hook_error", "Hook execution failed", err)
 		return
 	}
 
-	h.sendResponseWithOptions(w, responseData, nil, &options)
+	logger.Info("Successfully updated record with ID: %v", targetID)
+	h.sendResponseWithOptions(w, hookCtx.Result, nil, &options)
 }
 
 func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id string, data interface{}) {
@@ -1199,6 +1122,196 @@ func (h *Handler) handleDelete(ctx context.Context, w common.ResponseWriter, id
 	h.sendResponse(w, responseData, nil)
 }
 
+// normalizeToSlice converts data to a slice. Single items become a 1-item slice.
+func (h *Handler) normalizeToSlice(data interface{}) []interface{} {
+	if data == nil {
+		return []interface{}{}
+	}
+
+	dataValue := reflect.ValueOf(data)
+	if dataValue.Kind() == reflect.Slice || dataValue.Kind() == reflect.Array {
+		result := make([]interface{}, dataValue.Len())
+		for i := 0; i < dataValue.Len(); i++ {
+			result[i] = dataValue.Index(i).Interface()
+		}
+		return result
+	}
+
+	// Single item - return as 1-item slice
+	return []interface{}{data}
+}
+
+// extractNestedRelations extracts nested relations from data, returning cleaned data and relations
+// This does NOT process the relations, just separates them for later processing
+func (h *Handler) extractNestedRelations(
+	data map[string]interface{},
+	model interface{},
+) (map[string]interface{}, map[string]interface{}, error) {
+	// Get model type for reflection
+	modelType := reflect.TypeOf(model)
+	for modelType != nil && (modelType.Kind() == reflect.Ptr || modelType.Kind() == reflect.Slice || modelType.Kind() == reflect.Array) {
+		modelType = modelType.Elem()
+	}
+
+	if modelType == nil || modelType.Kind() != reflect.Struct {
+		return data, nil, fmt.Errorf("model must be a struct type, got %v", modelType)
+	}
+
+	// Separate relation fields from regular fields
+	cleanedData := make(map[string]interface{})
+	relations := make(map[string]interface{})
+
+	for key, value := range data {
+		// Skip _request field
+		if key == "_request" {
+			continue
+		}
+
+		// Check if this field is a relation
+		relInfo := h.GetRelationshipInfo(modelType, key)
+		if relInfo != nil {
+			logger.Debug("Found nested relation field: %s (type: %s)", key, relInfo.RelationType)
+			relations[key] = value
+		} else {
+			cleanedData[key] = value
+		}
+	}
+
+	return cleanedData, relations, nil
+}
+
+// processChildRelationsWithParentID processes nested relations with a parent ID
+func (h *Handler) processChildRelationsWithParentID(
+	ctx context.Context,
+	processor *common.NestedCUDProcessor,
+	operation string,
+	relations map[string]interface{},
+	parentModel interface{},
+	parentID interface{},
+) error {
+	// Get model type for reflection
+	modelType := reflect.TypeOf(parentModel)
+	for modelType != nil && (modelType.Kind() == reflect.Ptr || modelType.Kind() == reflect.Slice || modelType.Kind() == reflect.Array) {
+		modelType = modelType.Elem()
+	}
+
+	if modelType == nil || modelType.Kind() != reflect.Struct {
+		return fmt.Errorf("model must be a struct type, got %v", modelType)
+	}
+
+	// Process each relation
+	for relationName, relationValue := range relations {
+		if relationValue == nil {
+			continue
+		}
+
+		// Get relationship info
+		relInfo := h.GetRelationshipInfo(modelType, relationName)
+		if relInfo == nil {
+			logger.Warn("No relationship info found for %s, skipping", relationName)
+			continue
+		}
+
+		// Process this relation with parent ID
+		if err := h.processChildRelationsForField(ctx, processor, operation, relationName, relationValue, relInfo, modelType, parentID); err != nil {
+			return fmt.Errorf("failed to process relation %s: %w", relationName, err)
+		}
+	}
+
+	return nil
+}
+
+// processChildRelationsForField processes a single nested relation field
+func (h *Handler) processChildRelationsForField(
+	ctx context.Context,
+	processor *common.NestedCUDProcessor,
+	operation string,
+	relationName string,
+	relationValue interface{},
+	relInfo *common.RelationshipInfo,
+	parentModelType reflect.Type,
+	parentID interface{},
+) error {
+	if relationValue == nil {
+		return nil
+	}
+
+	// Get the related model
+	field, found := parentModelType.FieldByName(relInfo.FieldName)
+	if !found {
+		return fmt.Errorf("field %s not found in model", relInfo.FieldName)
+	}
+
+	// Get the model type for the relation
+	relatedModelType := field.Type
+	if relatedModelType.Kind() == reflect.Slice {
+		relatedModelType = relatedModelType.Elem()
+	}
+	if relatedModelType.Kind() == reflect.Ptr {
+		relatedModelType = relatedModelType.Elem()
+	}
+
+	// Create an instance of the related model
+	relatedModel := reflect.New(relatedModelType).Elem().Interface()
+
+	// Get table name for related model
+	relatedTableName := h.getTableNameForRelatedModel(relatedModel, relInfo.JSONName)
+
+	// Prepare parent IDs for foreign key injection
+	parentIDs := make(map[string]interface{})
+	if relInfo.ForeignKey != "" && parentID != nil {
+		baseName := strings.TrimSuffix(relInfo.ForeignKey, "ID")
+		baseName = strings.TrimSuffix(strings.ToLower(baseName), "_id")
+		parentIDs[baseName] = parentID
+	}
+
+	// Process based on relation type and data structure
+	switch v := relationValue.(type) {
+	case map[string]interface{}:
+		// Single related object
+		_, err := processor.ProcessNestedCUD(ctx, operation, v, relatedModel, parentIDs, relatedTableName)
+		if err != nil {
+			return fmt.Errorf("failed to process single relation: %w", err)
+		}
+
+	case []interface{}:
+		// Multiple related objects
+		for i, item := range v {
+			if itemMap, ok := item.(map[string]interface{}); ok {
+				_, err := processor.ProcessNestedCUD(ctx, operation, itemMap, relatedModel, parentIDs, relatedTableName)
+				if err != nil {
+					return fmt.Errorf("failed to process relation item %d: %w", i, err)
+				}
+			}
+		}
+
+	case []map[string]interface{}:
+		// Multiple related objects (typed slice)
+		for i, itemMap := range v {
+			_, err := processor.ProcessNestedCUD(ctx, operation, itemMap, relatedModel, parentIDs, relatedTableName)
+			if err != nil {
+				return fmt.Errorf("failed to process relation item %d: %w", i, err)
+			}
+		}
+
+	default:
+		return fmt.Errorf("unsupported relation data type: %T", relationValue)
+	}
+
+	return nil
+}
+
+// getTableNameForRelatedModel gets the table name for a related model
+func (h *Handler) getTableNameForRelatedModel(model interface{}, defaultName string) string {
+	if provider, ok := model.(common.TableNameProvider); ok {
+		tableName := provider.TableName()
+		if tableName != "" {
+			return tableName
+		}
+	}
+	return defaultName
+}
+
 // qualifyColumnName ensures column name is fully qualified with table name if not already
 func (h *Handler) qualifyColumnName(columnName, fullTableName string) string {
 	// Check if column already has a table/schema prefix (contains a dot)

pkg/restheadspec/handler_nested_test.go

@@ -0,0 +1,393 @@
+package restheadspec
+
+import (
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+// Test models for nested CRUD operations
+type TestUser struct {
+	ID    int64      `json:"id" bun:"id,pk,autoincrement"`
+	Name  string     `json:"name"`
+	Posts []TestPost `json:"posts" gorm:"foreignKey:UserID"`
+}
+
+type TestPost struct {
+	ID       int64         `json:"id" bun:"id,pk,autoincrement"`
+	UserID   int64         `json:"user_id"`
+	Title    string        `json:"title"`
+	Comments []TestComment `json:"comments" gorm:"foreignKey:PostID"`
+}
+
+type TestComment struct {
+	ID      int64  `json:"id" bun:"id,pk,autoincrement"`
+	PostID  int64  `json:"post_id"`
+	Content string `json:"content"`
+}
+
+func (TestUser) TableName() string    { return "users" }
+func (TestPost) TableName() string    { return "posts" }
+func (TestComment) TableName() string { return "comments" }
+
+// Test extractNestedRelations function
+func TestExtractNestedRelations(t *testing.T) {
+	// Create handler
+	registry := &mockRegistry{
+		models: map[string]interface{}{
+			"users":    TestUser{},
+			"posts":    TestPost{},
+			"comments": TestComment{},
+		},
+	}
+	handler := NewHandler(nil, registry)
+
+	tests := []struct {
+		name               string
+		data               map[string]interface{}
+		model              interface{}
+		expectedCleanCount int
+		expectedRelCount   int
+	}{
+		{
+			name: "User with posts",
+			data: map[string]interface{}{
+				"name": "John Doe",
+				"posts": []map[string]interface{}{
+					{"title": "Post 1"},
+				},
+			},
+			model:              TestUser{},
+			expectedCleanCount: 1, // name
+			expectedRelCount:   1, // posts
+		},
+		{
+			name: "Post with comments",
+			data: map[string]interface{}{
+				"title": "Test Post",
+				"comments": []map[string]interface{}{
+					{"content": "Comment 1"},
+					{"content": "Comment 2"},
+				},
+			},
+			model:              TestPost{},
+			expectedCleanCount: 1, // title
+			expectedRelCount:   1, // comments
+		},
+		{
+			name: "User with nested posts and comments",
+			data: map[string]interface{}{
+				"name": "Jane Doe",
+				"posts": []map[string]interface{}{
+					{
+						"title": "Post 1",
+						"comments": []map[string]interface{}{
+							{"content": "Comment 1"},
+						},
+					},
+				},
+			},
+			model:              TestUser{},
+			expectedCleanCount: 1, // name
+			expectedRelCount:   1, // posts (which contains nested comments)
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			cleanedData, relations, err := handler.extractNestedRelations(tt.data, tt.model)
+			if err != nil {
+				t.Errorf("extractNestedRelations() error = %v", err)
+				return
+			}
+
+			if len(cleanedData) != tt.expectedCleanCount {
+				t.Errorf("Expected %d cleaned fields, got %d: %+v", tt.expectedCleanCount, len(cleanedData), cleanedData)
+			}
+
+			if len(relations) != tt.expectedRelCount {
+				t.Errorf("Expected %d relation fields, got %d: %+v", tt.expectedRelCount, len(relations), relations)
+			}
+
+			t.Logf("Cleaned data: %+v", cleanedData)
+			t.Logf("Relations: %+v", relations)
+		})
+	}
+}
+
+// Test shouldUseNestedProcessor function
+func TestShouldUseNestedProcessor(t *testing.T) {
+	registry := &mockRegistry{
+		models: map[string]interface{}{
+			"users": TestUser{},
+			"posts": TestPost{},
+		},
+	}
+	handler := NewHandler(nil, registry)
+
+	tests := []struct {
+		name     string
+		data     map[string]interface{}
+		model    interface{}
+		expected bool
+	}{
+		{
+			name: "Data with nested posts",
+			data: map[string]interface{}{
+				"name": "John",
+				"posts": []map[string]interface{}{
+					{"title": "Post 1"},
+				},
+			},
+			model:    TestUser{},
+			expected: true,
+		},
+		{
+			name: "Data without nested relations",
+			data: map[string]interface{}{
+				"name": "John",
+			},
+			model:    TestUser{},
+			expected: false,
+		},
+		{
+			name: "Data with _request field",
+			data: map[string]interface{}{
+				"_request": "insert",
+				"name":     "John",
+			},
+			model:    TestUser{},
+			expected: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := handler.shouldUseNestedProcessor(tt.data, tt.model)
+			if result != tt.expected {
+				t.Errorf("shouldUseNestedProcessor() = %v, expected %v", result, tt.expected)
+			}
+		})
+	}
+}
+
+// Test normalizeToSlice function
+func TestNormalizeToSlice(t *testing.T) {
+	registry := &mockRegistry{}
+	handler := NewHandler(nil, registry)
+
+	tests := []struct {
+		name     string
+		input    interface{}
+		expected int // expected slice length
+	}{
+		{
+			name:     "Single object",
+			input:    map[string]interface{}{"name": "John"},
+			expected: 1,
+		},
+		{
+			name: "Slice of objects",
+			input: []map[string]interface{}{
+				{"name": "John"},
+				{"name": "Jane"},
+			},
+			expected: 2,
+		},
+		{
+			name: "Array of interfaces",
+			input: []interface{}{
+				map[string]interface{}{"name": "John"},
+				map[string]interface{}{"name": "Jane"},
+				map[string]interface{}{"name": "Bob"},
+			},
+			expected: 3,
+		},
+		{
+			name:     "Nil input",
+			input:    nil,
+			expected: 0,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := handler.normalizeToSlice(tt.input)
+			if len(result) != tt.expected {
+				t.Errorf("normalizeToSlice() returned slice of length %d, expected %d", len(result), tt.expected)
+			}
+		})
+	}
+}
+
+// Test GetRelationshipInfo function
+func TestGetRelationshipInfo(t *testing.T) {
+	registry := &mockRegistry{}
+	handler := NewHandler(nil, registry)
+
+	tests := []struct {
+		name         string
+		modelType    reflect.Type
+		relationName string
+		expectNil    bool
+	}{
+		{
+			name:         "User posts relation",
+			modelType:    reflect.TypeOf(TestUser{}),
+			relationName: "posts",
+			expectNil:    false,
+		},
+		{
+			name:         "Post comments relation",
+			modelType:    reflect.TypeOf(TestPost{}),
+			relationName: "comments",
+			expectNil:    false,
+		},
+		{
+			name:         "Non-existent relation",
+			modelType:    reflect.TypeOf(TestUser{}),
+			relationName: "nonexistent",
+			expectNil:    true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := handler.GetRelationshipInfo(tt.modelType, tt.relationName)
+			if tt.expectNil && result != nil {
+				t.Errorf("Expected nil, got %+v", result)
+			}
+			if !tt.expectNil && result == nil {
+				t.Errorf("Expected non-nil relationship info")
+			}
+			if result != nil {
+				t.Logf("Relationship info: FieldName=%s, JSONName=%s, RelationType=%s, ForeignKey=%s",
+					result.FieldName, result.JSONName, result.RelationType, result.ForeignKey)
+			}
+		})
+	}
+}
+
+// Mock registry for testing
+type mockRegistry struct {
+	models map[string]interface{}
+}
+
+func (m *mockRegistry) Register(name string, model interface{}) {
+	m.RegisterModel(name, model)
+}
+
+func (m *mockRegistry) RegisterModel(name string, model interface{}) error {
+	if m.models == nil {
+		m.models = make(map[string]interface{})
+	}
+	m.models[name] = model
+	return nil
+}
+
+func (m *mockRegistry) GetModelByEntity(schema, entity string) (interface{}, error) {
+	if model, ok := m.models[entity]; ok {
+		return model, nil
+	}
+	return nil, fmt.Errorf("model not found: %s", entity)
+}
+
+func (m *mockRegistry) GetModelByName(name string) (interface{}, error) {
+	if model, ok := m.models[name]; ok {
+		return model, nil
+	}
+	return nil, fmt.Errorf("model not found: %s", name)
+}
+
+func (m *mockRegistry) GetModel(name string) (interface{}, error) {
+	return m.GetModelByName(name)
+}
+
+func (m *mockRegistry) HasModel(schema, entity string) bool {
+	_, ok := m.models[entity]
+	return ok
+}
+
+func (m *mockRegistry) ListModels() []string {
+	models := make([]string, 0, len(m.models))
+	for name := range m.models {
+		models = append(models, name)
+	}
+	return models
+}
+
+func (m *mockRegistry) GetAllModels() map[string]interface{} {
+	return m.models
+}
+
+// TestMultiLevelRelationExtraction tests extracting deeply nested relations
+func TestMultiLevelRelationExtraction(t *testing.T) {
+	registry := &mockRegistry{
+		models: map[string]interface{}{
+			"users":    TestUser{},
+			"posts":    TestPost{},
+			"comments": TestComment{},
+		},
+	}
+	handler := NewHandler(nil, registry)
+
+	// Test data with 3 levels: User -> Posts -> Comments
+	testData := map[string]interface{}{
+		"name": "John Doe",
+		"posts": []map[string]interface{}{
+			{
+				"title": "First Post",
+				"comments": []map[string]interface{}{
+					{"content": "Great post!"},
+					{"content": "Thanks for sharing!"},
+				},
+			},
+			{
+				"title": "Second Post",
+				"comments": []map[string]interface{}{
+					{"content": "Interesting read"},
+				},
+			},
+		},
+	}
+
+	// Extract relations from user
+	cleanedData, relations, err := handler.extractNestedRelations(testData, TestUser{})
+	if err != nil {
+		t.Fatalf("Failed to extract relations: %v", err)
+	}
+
+	// Verify user data is cleaned
+	if len(cleanedData) != 1 || cleanedData["name"] != "John Doe" {
+		t.Errorf("Expected cleaned data to contain only name, got: %+v", cleanedData)
+	}
+
+	// Verify posts relation was extracted
+	if len(relations) != 1 {
+		t.Errorf("Expected 1 relation (posts), got %d", len(relations))
+	}
+
+	posts, ok := relations["posts"]
+	if !ok {
+		t.Fatal("Expected posts relation to be extracted")
+	}
+
+	// Verify posts is a slice with 2 items
+	postsSlice, ok := posts.([]map[string]interface{})
+	if !ok {
+		t.Fatalf("Expected posts to be []map[string]interface{}, got %T", posts)
+	}
+
+	if len(postsSlice) != 2 {
+		t.Errorf("Expected 2 posts, got %d", len(postsSlice))
+	}
+
+	// Verify first post has comments
+	if _, hasComments := postsSlice[0]["comments"]; !hasComments {
+		t.Error("Expected first post to have comments")
+	}
+
+	t.Logf("Successfully extracted multi-level nested relations")
+	t.Logf("Cleaned data: %+v", cleanedData)
+	t.Logf("Relations: %d posts with nested comments", len(postsSlice))
+}