使用 Mongoose 将平面数据转换为 mongodb 中的层次结构

Question

我创建了一个具有以下属性的模型：

1. 身份证
2. 孩子们
3. 父母

如果父级设置为空，文档将被视为顶级父级。每个文档可能有也可能没有子列表，其中仅包含其他文档的 ID。

db.categories.insert( { _id: "MongoDB", children: [],name: '', parent: 'Databases'} )
db.categories.insert( { _id: "dbm", children: [], parent: 'Databases' } )
db.categories.insert( { _id: "Databases", children: [ "MongoDB", "dbm" ], parent: 'Programming' } )
db.categories.insert( { _id: "Languages", children: [], parent: 'Programming' } )
db.categories.insert( { _id: "Programming", children: [ "Databases", "Languages" ],parent: 'books' } )
db.categories.insert( { _id: "Books", children: [ "Programming" ],parent: null } )

从上面的模型中，我需要生成这样的输出：

{
    name: "books",
    nodes: [
        {
            name: "Programming",
            nodes: [
                {
                    name: "Databases",
                    nodes: [
                        {
                            name: "MonogoDB"
                        },
                        {
                            name: "dbm"
                        }
                    ]
                },
                {
                    name: "Languages"
                }
            ]
        }
    ]
}

到目前为止我已经尝试过了，但是由于 findByID() 的异步性质，我没有得到想要的结果。请提出更改建议。

myDoc.find({
    parent: null
  }, function (err, topics) {
    if (err) {
      return handleError(res, err);
    }
    var docTree = [];
    _.each(document, function(parentDoc) {
       var doc = {};
       doc.text = parentDoc.name;
      doc.nodes = [];
      _.each(parentDoc.children, function(child) {
        doc.nodes.push(processChildren(child));
      });
      docTree.push(doc);

    });



function processChildren(child) {

  myDoc.findById(child, function (err,item) {
    var doc = {};
    doc.name = item._doc.name;
    doc.nodes = [];
    if (item._doc.children === null) {
      return topic;
    } else {
      _.each(item._doc.children, function (chld) {
        processChildren(chld);
      });
    }
    return doc;
  });

};

Answer 1

您可以尝试在 find() 方法之后调用 lean() 方法，因为启用了精简选项的查询返回的文档是纯 JavaScript 对象。然后，您可以操纵这些对象以获得所需的层次结构。以下内容可能无法给出确切的预期结果，但会将您推向正确的方向：

Model.find({}).lean().exec(function (err, docs) {
    if (err) {
      return handleError(res, err);
    }
    var i, len, temp, top_level, id, parent, hierarchical, nodePendingObj, doc, _id, _parent, _children;
    i = 0;
    top_level = [];
    temp = {};
    obj = {};
    nodePendingObj = {};
    _id = '_id';
    _parent = 'parent';
    _children = 'children';

    _.each(docs, function(doc) {
        id = doc['_id'];
        parent = doc[_parent];
        temp[id] = doc;
        if (parent === undefined || parent === null) {      
            obj["name"] = id;
            obj["nodes"] = doc[_children];
            top_level.push(obj);
        } 
        else {
            if (temp[parent] !== undefined) {           
                if (temp[parent][_children] === undefined) {
                    temp[parent][_children] = [];
                }
                var o = {};
                o["name"] = id;
                if (doc[_children].length !== 0) o["nodes"] = doc[_children];
                temp[parent][_children].push(o);
            } else {            
                if (nodePendingObj[parent] === undefined) {
                    nodePendingObj[parent] = [];
                }
                var o = {};
                o["name"] = id;
                if (doc[_children].length !== 0) o["nodes"] = doc[_children];
                nodePendingObj[parent].push(o);             
            }    
            delete doc[_parent];
        }

        if (nodePendingObj[id] !== undefined) {     

            var len = nodePendingObj[id].length;
            if (doc[_children] === undefined) {
                doc[_children] = [];
            }
            while (len-- > 0) {
                doc[_children].push(nodePendingObj[id].shift());
            }
        }
    });

    if (top_level.length === 1) {
        hierarchical = top_level[0];
    } else if (top_level.length > 1) {
        hierarchical = {};
        hierarchical[_children] = top_level;
    } else {
        hierarchical = {};
    }
    console.log(JSON.stringify(hierarchical));
});

查看下面的演示。

var documents = [
	{
		"_id" : "MongoDB",
		"children" : [],
		"name" : "",
		"parent" : "Databases"
	},{
		"_id" : "dbm",
		"children" : [],
		"parent" : "Databases"
	},{
		"_id" : "Databases",
		"children" : [ 
			"MongoDB", 
			"dbm"
		],
		"parent" : "Programming"
	},{
		"_id" : "Languages",
		"children" : [],
		"parent" : "Programming"
	},{
		"_id" : "Programming",
		"children" : [ 
			"Databases", 
			"Languages"
		],
		"parent" : "books"
	},{
		"_id" : "books",
		"children" : [ 
			"Programming"
		],
		"parent" : null
	}
];
var i, len, temp, top_level, id, parent, hierarchical, nodePendingObj, doc, _id, _parent, _children;
i = 0;
top_level = [];
temp = {};
obj = {};
nodePendingObj = {};
_id = '_id';
_parent = 'parent';
_children = 'children';


_.each(documents, function(doc) {	
	id = doc['_id'];
	parent = doc[_parent];
	temp[id] = doc;
	if (parent === undefined || parent === null) {		
		obj["name"] = id;
		obj["nodes"] = doc[_children];
		top_level.push(obj);
	} 
	else {
		if (temp[parent] !== undefined) {			
			if (temp[parent][_children] === undefined) {
				temp[parent][_children] = [];
			}
			var o = {};
			o["name"] = id;
			if (doc[_children].length !== 0) o["nodes"] = doc[_children];
			temp[parent][_children].push(o);
		} else {			
			if (nodePendingObj[parent] === undefined) {
				nodePendingObj[parent] = [];
			}
			var o = {};
			o["name"] = id;
			if (doc[_children].length !== 0) o["nodes"] = doc[_children];
			nodePendingObj[parent].push(o);
			
		}    
		delete doc[_parent];
	}
	
	if (nodePendingObj[id] !== undefined) {		
		
		var len = nodePendingObj[id].length;
		if (doc[_children] === undefined) {
			doc[_children] = [];
		}
		while (len-- > 0) {
			doc[_children].push(nodePendingObj[id].shift());
		}
	}
});

if (top_level.length === 1) {
	hierarchical = top_level[0];
} else if (top_level.length > 1) {
	hierarchical = {};
	hierarchical[_children] = top_level;
} else {
	hierarchical = {};
}

pre.innerHTML = JSON.stringify(hierarchical, null, 4);

<script src="//cdnjs.cloudflare.com/ajax/libs/underscore.js/1.7.0/underscore-min.js"></script>
<pre id="pre"></pre>