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.
For manage a nested tree node like this:
Video taken from BlueDoc, used by awesome_nested_set + react-dnd.
go get github.com/longbridgeapp/nested-set 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 }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)// 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").Error$ 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;MIT