Fixed filterExtendedOptions

pkg/restheadspec/handler.go

@@ -127,7 +127,7 @@ func (h *Handler) Handle(w common.ResponseWriter, r common.Request, params map[s
 
 	// Validate and filter columns in options (log warnings for invalid columns)
 	validator := common.NewColumnValidator(model)
-	options = filterExtendedOptions(validator, options)
+	options = h.filterExtendedOptions(validator, options, model)
 
 	// Add request-scoped data to context (including options)
 	ctx = WithRequestData(ctx, schema, entity, tableName, model, modelPtr, options)
@@ -2241,7 +2241,7 @@ func (h *Handler) setRowNumbersOnRecords(records any, offset int) {
 }
 
 // filterExtendedOptions filters all column references, removing invalid ones and logging warnings
-func filterExtendedOptions(validator *common.ColumnValidator, options ExtendedRequestOptions) ExtendedRequestOptions {
+func (h *Handler) filterExtendedOptions(validator *common.ColumnValidator, options ExtendedRequestOptions, model interface{}) ExtendedRequestOptions {
 	filtered := options
 
 	// Filter base RequestOptions
@@ -2265,12 +2265,30 @@ func filterExtendedOptions(validator *common.ColumnValidator, options ExtendedRe
 	// No filtering needed for ComputedQL keys
 	filtered.ComputedQL = options.ComputedQL
 
-	// Filter Expand columns
+	// Filter Expand columns using the expand relation's model
 	filteredExpands := make([]ExpandOption, 0, len(options.Expand))
+	modelType := reflect.TypeOf(model)
+	if modelType.Kind() == reflect.Ptr {
+		modelType = modelType.Elem()
+	}
+
 	for _, expand := range options.Expand {
 		filteredExpand := expand
-		// Don't validate relation name, only columns
-		filteredExpand.Columns = validator.FilterValidColumns(expand.Columns)
+
+		// Get the relationship info for this expand relation
+		relInfo := h.getRelationshipInfo(modelType, expand.Relation)
+		if relInfo != nil && relInfo.relatedModel != nil {
+			// Create a validator for the related model
+			expandValidator := common.NewColumnValidator(relInfo.relatedModel)
+			// Filter columns using the related model's validator
+			filteredExpand.Columns = expandValidator.FilterValidColumns(expand.Columns)
+		} else {
+			// If we can't find the relationship, log a warning and skip column filtering
+			logger.Warn("Cannot validate columns for unknown relation: %s", expand.Relation)
+			// Keep the columns as-is if we can't validate them
+			filteredExpand.Columns = expand.Columns
+		}
+
 		filteredExpands = append(filteredExpands, filteredExpand)
 	}
 	filtered.Expand = filteredExpands