Retrieving MongoDB Subdocuments with Node.js and Express.js

Question

I created a RESTful API using node.js, express.js, and mongodb. I started creating my routes by pulling documents from a MongoDB collection which work perfectly.

Example Collection Document

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

Works - and it also works if I do a .find({query}) instead of a generic find()

   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);
            });
        });
    };

But when I try to call a embedded document (i.e. subdocument) it using dot.notation it breaks.

*Doesn't Work*

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

Or even if I try

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

I get an error message saying.

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)

Can anybody help me find a workaround, or let me know if there are any errors with my approach.

Thanks!

Can you describe what's in the collection? Otherwise, I can't give you any more information that you can get from that error message. — Aaron Dufour
– Aaron Dufour, Commented Jun 4, 2013 at 19:52
That suggests that the json serializer is running into a circular argument — christkv
– christkv, Commented Aug 12, 2013 at 10:30

christkv · Accepted Answer · 2013-08-12 10:34:05Z

1

You've basically done this

> 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)

Somewhere in your code you are creating a self-referential object

answered Aug 12, 2013 at 10:34

community wiki

christkv

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Retrieving MongoDB Subdocuments with Node.js and Express.js

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related