node.js 中树结构的递归

Question

任务是在 node.js 中递归地构建一个树形结构。也就是说，我使用一组幻灯片，其中可能还包括其他子甲板。我是函数式编程的新手，我一直在理解我需要做什么。我知道，有更高级的方法来控制流量，但如果可能的话，我想一开始尝试以嵌套方式进行。我现在拥有的：

1. server.js 调用一个 api 并返回一个 json 对象：

   router.get('/deck/tree/:rev_id', function(req, res) {       
       var Deck = require('./models/deck');
       var deck = new Deck(connection);
       deck.getTree(req.params.rev_id ,function (tree) {res.json(tree)});      
   });
   

2. 在甲板模块中，我有几个功能： 2.a 获取牌组标题的函数：

   this.getTitle = function(rev_id, callback){
       var sql = "SELECT title FROM ?? WHERE ?? = ?";
       var inserts = ['deck_revision', 'id', rev_id];
       sql = mysql.format(sql, inserts);
       connection.query(sql, function(err, results) {
       if (err) throw err;
   
       callback(results[0].title);
       }); 
   };
   

2.b 获取甲板“直接”子代的函数：

this.getChildren = function(acc, callback){
    acc.children = [];
    var sql = "SELECT item_id AS id, item_type AS type FROM ?? WHERE ?? = ? ORDER BY position";
        var inserts = ['deck_content', 'deck_revision_id', acc.id];
        sql = mysql.format(sql, inserts);
        connection.query(sql, function(err, results) {
            if (err) throw err;
            results.forEach(function(res_item){
                acc.children.push({'id': res_item.id, 'type': res_item.type});
                if (acc.children.length === results.length){
                    callback(acc);
                }
            });
        });     
};

1. 应该建立树的功能（暂时不起作用）：

   var results = [];
   this.getTree = function(id, callback) {
       var acc = {};   
       var deck = this;
       var new_slide = new Slide(connection);
       deck.getTitle(id, function (title_str) {
           acc.title = title_str;
           acc.id = id;
           acc.type = 'deck';
           deck.getChildren(acc, function(new_acc){
               new_acc.children.forEach(function(element){
                   if (element.type === 'deck'){
   
         // I suppose the help is needed here!    
   
                       deck.getTree(element.id, function(new_element){
                           results.push(new_element);
                           if(results.length === new_acc.children.length) {
                               callback(results);
                           }
                       });
   
                   }else{
                       new_slide.getTitle(element.id, function(title_str){
                           element.title = title_str;
                           results.push(element);
                           if(results.length === new_acc.children.length) {
                               callback(results);
                           }
                       });
   
                   }
   

Answer 1

如果有人感兴趣，这里是我/已经使它工作的方式：

 this.getChildren = function(id, callback){
    var sql = "SELECT item_id AS id, item_type AS type, position FROM ?? WHERE ?? = ? ORDER BY position";
    var inserts = ['deck_content', 'deck_revision_id', id];
    sql = mysql.format(sql, inserts);
    connection.query(sql, function(err, results) {
        if (err) throw err;
        callback(results);
    }); 
};

 this.getTree = function(id, acc, callback) {
    deck = new Deck(connection);
    var new_slide = new Slide(connection);
    deck.getTitle(id, function (title_str) {
        acc.title = title_str;
        acc.id = id;
        acc.type = 'deck';
        acc.children = [];
        deck.getChildren(acc.id, function(children){
            children.forEach(function(element){
                if (element.type === 'deck'){
                    deck.getTree(element.id, element, function(new_element){
                        acc.children[new_element.position - 1] = new_element;
                        var size = acc.children.filter(function(value) { return value !== null }).length;
                        if (size === children.length){
                            callback(acc);
                        }
                    });                            
                }
                else{
                    new_slide.getTitle(element.id, function(title_str){
                        element.title = title_str;
                        acc.children[element.position - 1] = element;
                        var size = acc.children.filter(function(value) { return value !== null }).length;
                        if(size === children.length) {
                            callback(acc);
                        }
                    });                            
                }
            });                    
        });
    });
};