Nested Set for Go
Nested Set is an implementation of the Nested set model for Gorm.
This project is the Go version of awesome_nested_set, which uses the same data structure design, so it uses the same data together with awesome_nested_set.
Actually the original design is for this, the content managed by awesome_nested_set in our Rails application, the front-end Go API also needs to be maintained.
This is a Go version of the awesome_nested_set, and it built for compatible with awesome_nested_set.
What Go Nested Set can do?
For manage a nested tree node like this:
Video taken from BlueDoc, used by awesome_nested_set + react-dnd.
Installation
go get github.com/longbridgeapp/nested-set
Usage
Define the model
You must use nestedset Stuct tag to define your Gorm model like this:
Support struct tags:
id- int64 - Primary key of the nodeparent_id- sql.NullInt64 - ParentID column, null is rootlft- intrgt- intdepth- int - Depth of the nodechildren_count- Number of children
Optional:
scope- restricts what is to be considered a list. You can also setup scope by multiple attributes.
Example:
import (
"database/sql"
"github.com/longbridgeapp/nested-set"
)
// Category
type Category struct {
ID int64 `gorm:"PRIMARY_KEY;AUTO_INCREMENT" nestedset:"id"`
ParentID sql.NullInt64 `nestedset:"parent_id"`
UserType string `nestedset:"scope"`
UserID int64 `nestedset:"scope"`
Rgt int `nestedset:"rgt"`
Lft int `nestedset:"lft"`
Depth int `nestedset:"depth"`
ChildrenCount int `nestedset:"children_count"`
Title string
}Move Node
import nestedset "github.com/longbridgeapp/nested-set"
// create a new node root level last child
nestedset.Create(tx, &node, nil)
// create a new node as parent first child
nestedset.Create(tx, &node, &parent)
// nestedset.MoveDirectionLeft
// nestedset.MoveDirectionRight
// nestedset.MoveDirectionInner
nestedset.MoveTo(tx, node, to, nestedset.MoveDirectionLeft)Get Nodes with tree order
// With scope, limit tree in a scope
tx := db.Model(&Category{}).Where("user_type = ? AND user_id = ?", "User", 100)
// Get all nodes
categories, _ := tx.Order("lft asc").Error
// Get root nodes
categories, _ := tx.Where("parent_id IS NULL").Order("lft asc").Error
// Get childrens
categories, _ := tx.Where("parent_id = ?", parentCategory.ID).Order("lft asc").ErrorTesting
$ createdb nested-set-test
$ go test ./...-- 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