Rekursive Funktion in node.js mit q Bibliothek

Question

Ich muss JSON vorbereiten, indem Sie die Daten aus MYSQL. Ich habe Daten in MYSQl in der Baumstruktur. Ich versuche, rekursive Funktion zu machen JSON vorzubereiten, um die Anforderung aber immer Fehler gerecht zu werden, habe ich folgende zwei Dateien

main.js

/* jshint node: true */ 
"use strict"; 

var db = require('./helpers/db'); 
var list_worker = require('./workers/list'); 
var Q = require("q"); 

module.exports = function (app) { 
/** 
* return the profiles list 
*/ 
app.get('/api/lists/get_list_tree_by_user/:user_id', function (req, res) { 

    list_worker.fetch_list_tree(req.params.user_id, 0).done(function (out) { 
     console.log(out); 
     res.send(out); 
    }); 
}); 
}; 

list.js

/* jshint node: true */ 
"use strict"; 

var db = require('../helpers/db'); 
var Q = require("q"); 
var output = { 
    data: [] 
}; 

var fetch_list_tree = function (user_id, list_id) { 

// prepare query to fetch lists assosiated with a user. 
var query = "SELECT b.`id`, b.`name` FROM `lists_users` a JOIN `lists` b ON(a.`list_id` = b.`id`) WHERE a.`user_id` = " + user_id + " AND a.`user_role` = 'owner' AND b.`parent_id` = " + list_id + " AND b.`deleted` = 'N';"; 

return db.query(query).then(function (result) { 

    if (result.length > 0) { 
     var lists = result.map(function (list, index) { 

      output.data[index] = { 
       label: list.name, 
       data: { 
        id: list.id 
       } 
      }; 

      return fetch_list_tree(user_id, list.id).then(function (leaf_childs) { 
       output.data[index].children = []; 
       output.data[index].children.push(leaf_childs); 
       return leaf_childs; 
      }); 
     }); 

     return Q.all(lists).then(function (data) { 
      return output; 
     }, function (err) { 
      throw err; 
     }); 
    } else { 
     return []; 
    } 
}, function (err) { 
    throw err; 
}); 
}; 

module.exports = { 
    fetch_list_tree: fetch_list_tree 
}; 

Daten in der Datenbank ich habe ist Artikel 1 Punkt 1.1 Artikel 1.1.1 Artikel 2

Ausgang Ich möchte { "label": "item 1", "data": { "id": "1" }, "children": [{ "label": "item 1.1", "data": { "id": "2" }, "children": [{ "label": "item 1.1.1", "data": { "id": "3" }, "children": [] }] }] }

ich folgende Fehlermeldung

TypeError: Converting circular structure to JSON

Answer 1

Versuchen Änderung this.fetch_list_tree zu exports.fetch_list_tree bin immer.

this != module.exports on line 28 => undefined