Is it possible to have a Mongoose Schema that resembles the following:

var categorySchema = new Schema({
    name : String
});

var childSchema = new Schema({
   name : String,
   category : {
      type : Schema.Types.ObjectId,
      ref : 'parent.categories'
   }
});

var parentSchema = new Schema({
    categories : [categorySchema],
    children : [childSchema]
});

Basically a child can only have a category that is contained by its parent. Is what I am trying to do possible? If not what is the cleanest way to do this?

Is it possible to have a Mongoose Schema that resembles the following:

var categorySchema = new Schema({
    name : String
});

var childSchema = new Schema({
   name : String,
   category : {
      type : Schema.Types.ObjectId,
      ref : 'parent.categories'
   }
});

var parentSchema = new Schema({
    categories : [categorySchema],
    children : [childSchema]
});

Basically a child can only have a category that is contained by its parent. Is what I am trying to do possible? If not what is the cleanest way to do this?

• javascript
• node.js
• mongodb
• mongoose

1 Answer 1

If there is only one field name in categorySchema, maybe you could just put it into parentSchema without population as below,

var childSchema = new Schema({
   name : String,
   category : {
      name: String
   }
});

var parentSchema = new Schema({
    categories : [{name: String}],
    children : [childSchema]
});

When try to insert new child into parent, you could query the parent firstly, then iterate categories to get existing one and add it to children, save the parent as last, sample codes as below

Parent.find({_id: parent._id})
      .exec(function(err, p) {
          if (err) throw err;
          var p = new Child({name: 'tt'});
          p.categories.forEach(function(c) {
              if (c /*find the match one*/) {
                  p.category = c; // assign the existing category to children
              }
          });
          // save this parent
          p.save(function(err) {...});
      });  

If there are many fields in categorySchema, maybe define it as individual schema could be one option, in case of there are many categories in Parent to make parent collection too large.

var categorySchema = new Schema({
    name : String,
    // other fields....
});
var Category = mongoose.model('Category', categorySchema);

var childSchema = new Schema({
   name : String,
   category : {type : Schema.Types.ObjectId, ref : 'Category'}
});

var parentSchema = new Schema({
    categories : [{type : Schema.Types.ObjectId, ref : 'Category'}],
    children : [childSchema]
});

The same logic when try to add new children to parent document as above.