Last Updated: February 23, 2018
· edtheprogrammer

Saving Sub-Documents With Mongoose

I'm pretty new to mongoDB and the popular ORM Mongoose. And I just spent way too much time trying to figure out the proper way to save sub-documents in mongoose. The mongoose documentation shows you how to assign values to each property of a sub-document when pushing it onto the sub-document array, but how often will you do that? If you are using Mongoose, you probably have a model for the sub-document and you are probably passing that around between your controllers and models. So how does one persist a model of a sub-document to the parent document? Here is an example:

First, the model and schema stuff:

var Schema = mongoose.Schema;
var ObjectId = Schema.ObjectId;

var childSchema = new Schema({
     foo: String

var Child = mongoose.model('Child',childSchema);

model['Child'] = Child;

var parentSchema = new Schema({
    parent_foo: String
    ,children: [model["Child"].schema]

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

model['Parent'] = Parent;

And here is an example of how to save the sub-document (assuming myParent is an object of type Parent and myChild is an object of type Child):



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Why did you need this line of code?

model['Child'] = Child;

Couldn't you just do this in the parent?

,children: [Child.schema]

over 1 year ago ·

bighi, you don't need it.

side note--i had been stuck because i was (apparently) misreading the docs, thinking that "children" was somehow an actual method that was available. Wasn't 'til i saw your full example that they were just referring to the specific child field (meaning you can have multiple children and refer to them separatly---DERP)

over 1 year ago ·

The mongoose document about this feature is too damn bad explained. Reading this article, I understand that you can't add a children schema to it's parent without create a children model first. That should be explained by official mongoose docs.

7 days ago ·