load tags into tree, display them as tree with depth 2, ordered

tags/tags.go

@@ -4,47 +4,43 @@ import (
     "database/sql"	
 	_ "github.com/lib/pq"
 	"fmt"
-	"strings"
-	"strconv"
 )
 
 type Tag struct {
+    Id int
     Name string
     Parent sql.NullInt64
-    Children []int
+    Children []*Tag
 }
 
-var Tags map[int]*Tag
+var Tags []*Tag
 
 func LoadTags(db *sql.DB) {
-    Tags = make(map[int]*Tag)
-   	rows, err := db.Query("select tags.tag_id, tags.name, tags.parent_id, array_agg(distinct(parent_of.tag_id)) as children from tags left join tags as parent_of on parent_of.parent_id=tags.tag_id group by tags.tag_id")
+    Tags = []*Tag{}
+   	//rows, err := db.Query("select tags.tag_id, tags.name, tags.parent_id, array_agg(distinct(parent_of.tag_id)) as children from tags left join tags as parent_of on parent_of.parent_id=tags.tag_id group by tags.tag_id")
+   	rows, err := db.Query("select tags.tag_id, tags.name, tags.parent_id from tags order by tag_id,tags.parent_id desc")
     if err != nil {
         fmt.Println("DB Error loading tags:", err)
         return
     }	
 	
-	for rows.Next() {
-		tag := &Tag{Children: nil}
+	var flatMap map[int]*Tag = make(map[int]*Tag)
 	
-		var children sql.NullString
-		var tag_id int
-		err = rows.Scan(&tag_id, &tag.Name, &tag.Parent, &children)
+	for rows.Next() {
+		tag := &Tag{Children: []*Tag{}}
+
+		err = rows.Scan(&tag.Id, &tag.Name, &tag.Parent)
 		if err != nil {
 			fmt.Println("tags DB Error: ", err)
 		}
 		
-		if children.Valid {
-			var childrenStr = children.String[1 : len(children.String)-1]
-			if childrenStr != "NULL" {
-				pids := strings.Split(childrenStr, ",")
-				for _, spid := range pids {
-					pid, _ := strconv.Atoi(spid)
-					tag.Children = append(tag.Children, pid)
-				}	
-			}
-		}
+		flatMap[tag.Id] = tag
 		
-		Tags[tag_id] = tag
+		if tag.Parent.Valid {
+		    pid := int(tag.Parent.Int64)
+		    flatMap[pid].Children = append(flatMap[pid].Children, tag)
+		} else {
+		    Tags = append(Tags, tag)
+		}    
 	}
 }

templates/pages/add.html

@@ -21,5 +21,8 @@
 
 
 {{define "option-tag"}}
-    <option>{{.Name}}</option>        
+    <option value="{{.Id}}">{{if .Parent.Valid}}-{{end}}{{.Name}}</option>
+    {{range $child := .Children}}
+        {{template "option-tag" $child}}
+     {{end}}            
 {{end}}