Mongoose, CastError: Cast to Array failed for value when trying to save a model that contains a model

Question

I am trying to create the model for my mongodb database using mongoose. This is what I am trying to do:

var Class = mongoose.model(\'Class\', {className: St         


        

Answer 1

Explicitly defining the type rule on a property called type is allowed and won't throw an error. like this:

type: {type: String}

Answer 2

By default, if you have an object with key 'type' in your schema, mongoose will interpret it as a type declaration.

// Mongoose interprets this as 'loc is a String'
var schema = new Schema({ loc: { type: String, coordinates: [Number] } });

Changing the typeKey:

var schema = new Schema({
  // Mongoose interpets this as 'loc is an object with 2 keys, type and coordinates'
  loc: { type: String, coordinates: [Number] },
  // Mongoose interprets this as 'name is a String'
  name: { $type: String }
}, { typeKey: '$type' }); // A '$type' key means this object is a type declaration

Link: http://mongoosejs.com/docs/guide.html#typeKey

Answer 3

Just for Update

Now Mongoose supports subdocuments, which are the documented way to nest arrays,

var arraySchema = new Schema({
    property: String
});

var objectSchema = new Schema({
    arrays: [arraySchema]
});

Sources

http://mongoosejs.com/docs/schematypes.html

Answer 4

I got a similar issue using mongoose 5.7.0+ using double nested schema.

Except it wasn't related to the keyword type but a mongoose validation bug.

https://github.com/Automattic/mongoose/issues/8472

Temporary workaround: Use Schema.Types.Mixed for the subschema

Answer 5

Try changing the class definition to :

var classSchema = mongoose.Schema({className: String, marks: [{type: Number}], grades: [{type: Number}]});
var userSchema = mongoose.Schema({email: String, classes: [classSchema] });
var User = mongoose.model('User',userSchema);

This is required since mongoose is not able to parse the object without a related schema. Now when you create a new Schema for the internal class object and refer it in the main userSchema mongoose should be able to parse your object.

Answer 6

Man, I had a similar issue creating an Schema like this:

QuestionnaireSchema = mongoose.Schema({
    formId: Number,
    name: String,
    questions: [
        {
            type: String,
            title: String,
            alternatives:[{
                label: String,
                value: "Mixed"
            }]
        }
    ]
});

My mistake was that I am using "type" as a field name and this is reserved word in mongoose.

I just change:

type: String,

to

formType: String,

and that works.

see: https://github.com/Automattic/mongoose/issues/1760