node.js - 使用 Node.js 和 Express.js 检索 MongoDB 子文档

Question

我使用 node.js、express.js 和 mongodb 创建了一个 RESTful API。我开始通过从运行良好的 MongoDB 集合中提取文档来创建我的路由。

示例集合文档

{ 
"_id" : ObjectId("51ace8c04cc8ea865df0923e"), 
"title" : "Some Example Title", 
"producer" : 
 { 
  "company" : "Your Company Name"
 } 
}

有效 - 如果我执行 .find({query}) 而不是通用的 find()，它也有效

   app.get('/something', something.findAll);
    exports.findAll = function(req, res) {
        db.collection('something', function(err, collection) {
            collection.find().toArray(function(err, items) {
                res.contentType('json');
                res.header("Access-Control-Allow-Origin", "*");
                res.header('Access-Control-Allow-Methods', 'GET, PUT');
                res.header('Access-Control-Allow-Headers', 'Content-Type, Authorization');
                res.send(items);
            });
        });
    };

但是，当我尝试使用点符号调用嵌入文档(即子文档)时，它会中断。

*不起作用*

db.something.find( { 'producer.company': 'ABC123' } )

或者即使我尝试

db.something.find( {producer: {company: 'ABC123'} } );

我收到一条错误消息。

TypeError: Converting circular structure to JSON
    at Object.stringify (native)
    at ServerResponse.res.json (../lib/response.js:185:19)
    at ServerResponse.res.send (..//lib/response.js:117:21)
    at ../routes/recipes.js:81:8
    at Collection.find (../node_modules/mongodb/lib/mongodb/collection.js:931:5)
    at ../routes/recipes.js:73:14
    at Db.collection (../lib/mongodb/db.js:462:44)
    at exports.findByCat (../routes/recipes.js:72:5)
    at callbacks (../node_modules/express/lib/router/index.js:161:37)
    at param (../node_modules/express/lib/router/index.js:135:11)

谁能帮我找到解决方法，或者让我知道我的方法是否有任何错误。

谢谢!

Answer 1

你基本上做到了这一点

> var a = {a:1}
undefined
> a.b = a
{ a: 1, b: [Circular] }
> JSON.stringify(a)
TypeError: Converting circular structure to JSON
    at Object.stringify (native)
    at repl:1:7
    at REPLServer.self.eval (repl.js:110:21)
    at Interface.<anonymous> (repl.js:239:12)
    at Interface.EventEmitter.emit (events.js:95:17)
    at Interface._onLine (readline.js:202:10)
    at Interface._line (readline.js:531:8)
    at Interface._ttyWrite (readline.js:760:14)
    at ReadStream.onkeypress (readline.js:99:10)
    at ReadStream.EventEmitter.emit (events.js:98:17)

您在代码中的某处创建了一个自引用对象