Return an associative array instead of a document array in mongoose

Question

Let's suppose I have a Word model with this schema

var Word = new Schema({
  name: { type: String, required: true },
  disambiguation: String,
  partOfSpeech: { type: ObjectId, ref: "PartOfSpeech", required: true },
  attributes: [{ type: ObjectId, ref: "Attribute"}],
  root: [{ type: ObjectId, ref: "Word"}],
  language: { type: ObjectId, ref: "Language", required: true }
});

I want to perform a query that returns an object, with word names as keys with and values as arrays of documents containing words with the corresponding name.

As an example, here is the sort of output I would like. Most fields are ommitted for brevity.

{
  stick: [{
    _id: "5024216f6df57b2b68834079",
    partOfSpeech: "noun"      
  }, {
    _id: "678451de6da54c2b68837345",
    partOfSpeech: "verb"
  }],
  dog: [{
    _id: "47cc67093475061e3d95369d",
    partOfSpeech: "noun"
  }]
}

This way, I can have random access to the list of words so I don't have to iterate over it repeatedly. Is there a built-in way to do this in mongoose?

JohnnyHK · Accepted Answer · 2012-09-03 00:45:36Z

2

You can't do this directly with Mongoose, but if you stream the results of a query you can build up your desired associative array pretty easily:

var stream = Word.find().stream(), results = {};
stream.on('data', function(doc) {
    if (results.hasOwnProperty(doc.name)) {
        results[doc.name].push(doc);
    } else {
        results[doc.name] = [doc];
    }
}).on('error', function(doc) {
    // Error handling...
}).on('close', function(doc) {
    // All done, results object is ready.
});

answered Sep 3, 2012 at 0:45

JohnnyHK

313k70 gold badges632 silver badges479 bronze badges

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

1 Comment

Izhaki Over a year ago

It seems this will simply return a single key with the document as its value, but not for the actual word entries (that will be plain objects, not key/value pairs). The stream simply gets one call to on('data'), with the whole document.

Erik · Accepted Answer · 2012-09-01 18:30:37Z

2

Word.find().lean().exec(function (err, docs) {
    // docs are plain javascript objects instead of model instances
});

answered Sep 1, 2012 at 18:30

Erik

14.9k49 gold badges141 silver badges223 bronze badges

1 Comment

Peter Olson Over a year ago

But it still returns an array instead of a key-value object

grantwparks · Accepted Answer · 2012-10-25 03:43:06Z

1

You can use a reduce function to "re-index" any array into a dictionary. I use underscore reduce in my example, but I would think with a little tweaking it could work directly in mongoose. http://techishard.wordpress.com/2012/04/22/reducing-an-array-of-objects-to-a-hash-using-a-property-as-key/

_.reduce (foo, function (reduced, item) {
 reduced[item.name] = item;
 return reduced;
}, {});

answered Oct 25, 2012 at 3:43

grantwparks

1,1639 silver badges13 bronze badges

Collectives™ on Stack Overflow

Return an associative array instead of a document array in mongoose

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Related