Golang Create tree from MySQL

This is a creation in Article, where the information may have evolved or changed.

Golang Web develop always using the tree menu in our project.then so can be Reference resources.this article teach how T o Get tree menu in Web project.

1.show table of menu in MySQL database

```mysql> desc menu;+-------+-------------+------+-----+---------+-------+| Field | Type        | Null | Key | Default | Extra |+-------+-------------+------+-----+---------+-------+| id    | int(11)     | YES  |     | NULL    |       || name  | varchar(50) | YES  |     | NULL    |       || pid   | int(11)     | YES  |     | NULL    |       |+-------+-------------+------+-----+---------+-------+3 rows in set (0.00 sec)

```mysql> select * from menu;+------+------+------+| id   | name | pid  |+------+------+------+|    1 | aa   |    0 ||    2 | bb   |    1 ||    3 | cc   |    1 ||    4 | dd   |    2 ||    5 | ee   |    3 ||    6 | ee   |    4 |+------+------+------+6 rows in set (0.00 sec)```

2.base operation in golang,that include tree files thats call db.go/menu.go/main.go

db.gopackage modelimport (    "database/sql"    "fmt"    _ "github.com/go-sql-driver/mysql")var (    dbURL = "root:root@tcp(127.0.0.1:3306)/test?charset=utf8")func Tx(v_sql string, args ...interface{}) (*sql.Rows, error) {    db, err := sql.Open("mysql", dbURL)    defer db.Close()    stmt, err := db.Prepare(v_sql)    if err != nil {        fmt.Println("Tx err:", err)        return nil, err    }    return stmt.Query(args...)}

Menu.gopackage modelimport ("Database/sql" "FMT") const (querysql = "Select Id,name,pid from menu where pid =?") ) Type menu struct {curid int64 ' JSON: "Curid" ' Name string ' JSON: ' Name ' ' ParentID Int64 ' JSON: "Parent ID "' Child []*menu ' JSON:" Child,omitempty "'}func menuappend (M *menu) {fmt. Println (querysql) Child, err: = Menuinit (Querysql, M.curid) if err! = Nil {fmt.    Println ("Menuappend err:", err) return} M.child = Child for _, V: = Range M.child {menuappend (v) }}func LoadMenu () (*menu, error) {MS, Err: = Menuinit (querysql, 0) if err! = Nil {fmt. Println ("LoadMenu err:", err) return nil, err} root: = Ms[0] Menuappend (root) return root, Nil}func Me Nuinit (sql0 string, id Int64) ([]*menu, error) {rows, err: = Tx (sql0, id) if err! = Nil {fmt. Println ("Meneinit err:", err) return nil, err} MS: = Make ([]*menu, 0) for rows. Next () {m: = &menu{} var ID sql. NullInt64 var name sql. nullstring var pid sql. NullInt64 If Err = rows. Scan (&id, &name, &pid); Err! = Nil {fmt. PRINTLN ("Menuinit error:", err) return nil, err} if ID. Valid {M.curid = ID. Int64} if name. Valid {m.name = Name. String} if PID. Valid {m.parentid = pid. Int64} ms = Append (MS, m)} FMT. PRINTLN ("Current data:", MS) return MS, nil}

main.gopackage mainimport (    "encoding/json"    "fmt"    _ "github.com/go-sql-driver/mysql"    "model")func main() {    root, err := model.LoadMenu()    if err != nil {        fmt.Println("err:", err)    }    b, err := json.Marshal(root)    fmt.Println(string(b))}

3.run and get tree data from JSON

{  "curid": 1,   "name": "aa",   "parentid": 0,   "child": [    {      "curid": 2,       "name": "bb",       "parentid": 1,       "child": [        {          "curid": 4,           "name": "dd",           "parentid": 2,           "child": [            {              "curid": 6,               "name": "ee",               "parentid": 4            }          ]        }      ]    },     {      "curid": 3,       "name": "cc",       "parentid": 1,       "child": [        {          "curid": 5,           "name": "ee",           "parentid": 3        }      ]    }  ]}