[mongoose] Creating a model with no collection

I would like to have a child schema that is *only* used as a sub-schema within a parent.   They will never exist independently of the parent schema.  I would also like to be able to compile a model on that schema to get the benefits of Model, such as methods.   Is it considered "valid" to call mongoose.model() will null as the collection?  Is there a better way to do what I'm trying to do?

Here is some code to demonstrate what I'm talking about:

var mongoose = require('mongoose'),

    Schema = mongoose.Schema;

var ChildSchema = new Schema({

  name : String,

});

ChildSchema.methods.hello = function () {

  console.log('Hi my name is ' + this.name);

};

ChildSchema.pre('save', function (next) {

  console.log('save middleware called for ' + this.name);

  next();

});

// collection set to null because we will NEVER be saving

// Child objects.  They only exist within parent documents.

var Child = mongoose.model('Child', ChildSchema, null);

var ParentSchema = new Schema({

  title : String,

  children : [ ChildSchema ],

});

// collection is implicitly 'parents'

var Parent = mongoose.model('Parent', ParentSchema);

var c = new Child( { name : 'Bobby'} );

// output:

// Hi my name is Bobby

c.hello();

var p = new Parent({

  title : 'I am the parent',

  children : [ c ],

});

// output:

// save middleware called for Bobby

p.save();

Calling mongoose.model with collection=null is valid, but won't give you the result you expect. Mongoose will treat that as if you didn't pass a collection name at all, and thus just use the implicit collection name. Right now there unfortunately isn't a good way to do what you're trying to do without setting some collection name for the model, but this is definitely something worth considering for v4.0.



I think this is the same issue I am having, which I posted here https://github.com/LearnBoost/mongoose/issues/2534