How to convert an interface{} to nested tree in Golang

The incoming interface{} will be converted to []map[string]interface{}.

Raw data type is []map[string]interface{} :

[
  {
    "ID": 1,
    "Name": "Root",
    "ParentID": 0,
    "Path": "Root"
  },
  {
    "ID": 2,
    "Name": "Ball",
    "ParentID": 1,
    "Path": "Root/Ball"
  },
  {
    "ID": 3,
    "Name": "Foot",
    "ParentID": 2,
    "Depth": 2,
    "Path": "Root/Ball/Foot"
  }
]

Hope to get type for json:

[
  {
    "ID": 1,
    "Name": "Root",
    "ParentID": 0,
    "Path": "Root",
    "Child": {
      "ID": 2,
      "Name": "Ball",
      "ParentID": 1,
      "Path": "Root/Ball",
      "Child": {
        "ID": 3,
        "Name": "Foot",
        "ParentID": 2,
        "Depth": 2,
        "Path": "Root/Ball/Foot"
      }
    }
  }
]

if methods of php:

$data = Raw data is array()...
    	
$result = array();
    	
$temp = array();
    	
foreach($data as $item) {
    if($item['ParentID'] == 0) {
        $result[$item['ID']] = $item;
        $temp[$item['ID']] =& $result[$item['ID']];
    }else {
        $temp[$item['ParentID']][$item['ID']] = $item;
        $temp[$item['ID']] =& $temp[$item['ParentID']][$item['ID']];
    }
}

return $result

golang is not run:

func tree(array interface{}) map[int]*[]map[string]interface{} {

	results := make(map[int]*map[string]interface{})
	temp := make(map[int]map[string]*map[string]interface{})
	for _, item := range maps(array) {

		id := int(item["ID"].(float64))
		pid := int(item["ParentID"].(float64))

		if pid == 0 {
			results[id] = item
			temp[id]["c"] = &results[id]
		} else {
			temp[pid]["c"] = item
			temp[id] = &temp[pid]["c"]
		}
	}
	return results
}

func maps(val interface{}) []map[string]interface{} {
	if b, err := json.Marshal(val); err == nil {
		var maps []map[string]interface{}
		json.Unmarshal(b, &maps)
		return maps
	}
	return nil
}

my english is not good.
only be expressed by way of code and google translation.
Hope to get everyone's help.

A good start would be to introduce

type Post struct {
  ID int
  Name string
  ParentID int
  Depth int
  Path string
}

var posts []Post

and use package encoding/json to Unmarshal the JSON list to a variable in Go.

Solution

package main
import (
"encoding/json"
"fmt"
)
var indata string = `[
{
"ID": 1,
"Name": "Root",
"ParentID": 0,
"Path": "Root"
},
{
"ID": 2,
"Name": "Ball",
"ParentID": 1,
"Path": "Root/Ball"
},
{
"ID": 3,
"Name": "Foot",
"ParentID": 2,
"Depth": 2,
"Path": "Root/Ball/Foot"
}
]`
type Node struct {
ID       int
Name     string
ParentID int
Depth    int
Path     string
Child    *Node
}
func main() {
nodes := []Node{}
err := json.Unmarshal([]byte(indata), &nodes)
if err != nil {
panic(err)
}
m := make(map[int]*Node)
for i, _ := range nodes {
//fmt.Printf("Setting m[%d] = <node with ID=%d>\n", n.ID, n.ID)
m[nodes[i].ID] = &nodes[i]
}
for i, n := range nodes {
//fmt.Printf("Setting <node with ID=%d>.Child to <node with ID=%d>\n", n.ID, m[n.ParentID].ID)
if m[n.ParentID] != nil {
m[n.ParentID].Child = &nodes[i]
}
}
outdata, err := json.Marshal(m[1])
if err != nil {
panic(err)
}
fmt.Println(string(outdata))
}

Go to https://play.golang.org/p/CMk1yhEOhd to test it.