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

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

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

type: {type: String}

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.