Merge pull request #14 from calebx/main

make sure we can not move node into slot related to its descendants

Author: griffinqiu

README.md

@@ -105,6 +105,16 @@ $ createdb nested-set-test
 $ go test ./...
 ```
 
+```SQL
+-- some useful sql to check status
+SELECT n.id,
+CONCAT(REPEAT('. . ', (COUNT(p.id) - 1)::int), n.title) AS t,
+n.title, n.lft, n.rgt, n.depth, n.children_count
+FROM categories AS n, categories AS p
+WHERE (n.lft BETWEEN p.lft AND p.rgt)
+GROUP BY n.id ORDER BY n.lft;
+```
+
 ## License
 
 MIT

nested_set.go

@@ -14,6 +14,7 @@ import (
 // MoveDirection means where the node is going to be located
 type MoveDirection int
 
+// MoveDirections ...
 const (
 	// MoveDirectionLeft : MoveTo(db, a, n, MoveDirectionLeft) => a|n|...
 	MoveDirectionLeft MoveDirection = -1
@@ -229,6 +230,11 @@ func MoveTo(db *gorm.DB, node, to interface{}, direction MoveDirection) error {
 		return err
 	}
 
+	err = moveIsValid(targetNode, toNode)
+	if err != nil {
+		return err
+	}
+
 	var right, depthChange int
 	var newParentID sql.NullInt64
 	if direction == MoveDirectionLeft || direction == MoveDirectionRight {
@@ -248,6 +254,15 @@ func MoveTo(db *gorm.DB, node, to interface{}, direction MoveDirection) error {
 	return moveToRightOfPosition(tx, targetNode, right, depthChange, newParentID)
 }
 
+func moveIsValid(node, to nestedItem) error {
+	validLft, validRgt := node.Lft, node.Rgt
+	if (to.Lft >= validLft && to.Lft <= validRgt) || (to.Rgt >= validLft && to.Rgt <= validRgt) {
+		return fmt.Errorf("in valid move target: %v => %v", node, to)
+	}
+
+	return nil
+}
+
 func moveToRightOfPosition(tx *gorm.DB, targetNode nestedItem, position, depthChange int, newParentID sql.NullInt64) error {
 	return tx.Transaction(func(tx *gorm.DB) (err error) {
 		oldParentID := targetNode.ParentID

nested_set_test.go

@@ -258,6 +258,24 @@ func TestMoveToInner(t *testing.T) {
 	assertNodeEqual(t, blouses, 19, 20, 2, 0, womens.ID)
 }
 
+func TestMoveIsInvalid(t *testing.T) {
+	initData()
+	err := MoveTo(db, womens, dresses, MoveDirectionInner)
+	assert.NotEmpty(t, err)
+	reloadCategories()
+	assertNodeEqual(t, womens, 10, 21, 1, 3, clothing.ID)
+
+	err = MoveTo(db, womens, dresses, MoveDirectionLeft)
+	assert.NotEmpty(t, err)
+	reloadCategories()
+	assertNodeEqual(t, womens, 10, 21, 1, 3, clothing.ID)
+
+	err = MoveTo(db, womens, dresses, MoveDirectionRight)
+	assert.NotEmpty(t, err)
+	reloadCategories()
+	assertNodeEqual(t, womens, 10, 21, 1, 3, clothing.ID)
+}
+
 func assertNodeEqual(t *testing.T, target Category, left, right, depth, childrenCount int, parentID int64) {
 	nullInt64ParentID := sql.NullInt64{Valid: false}
 	if parentID > 0 {