Mongoose: How to store multiple schema types in an mongoose subdocuments array

[AjitkumarB]

var modelSchema = new mongoose.Schema({
name: {
type: String
},
personas: [typeA | typeB] // need one of two types here(typeA schema,typeB schema)
});

var bigSchema = new mongoose.Schema({
title: {
type: String
},
model: modelSchema
})

[varunjayaraman]

You have to use a Mixed type: http://mongoosejs.com/docs/schematypes.html

Note: you will have to call doc.markModified() on the fields that you change if you go down this route.

[AjitkumarB]

Mixed type allows anything (without validating). As typeA and typeB are schemas and i want to validate them.
We can do this for normal schema using discriminators or "mongoose-schema-extend". But at subdocument level i didn't found any solution.

[varunjayaraman]

Yeah I don't think what you're asking for in terms of specifying a type like typeA | typeB is possible unless you compose your own custom schema for the subdocument or you used a Mixed type.

[vkarpov15]

= 4.8.0 supports this:

var eventSchema = new Schema({ message: String },
  { discriminatorKey: 'kind', _id: false });

var batchSchema = new Schema({ events: [eventSchema] });
batchSchema.path('events').discriminator('Clicked', new Schema({
  element: String
}, { _id: false }));
batchSchema.path('events').discriminator('Purchased', new Schema({
  product: String
}, { _id: false }));

var MyModel = db.model('gh2723', batchSchema);
var doc = {
  events: [
    { kind: 'Clicked', element: 'Test' },
    { kind: 'Purchased', product: 'Test2' }
  ]
};
MyModel.create(doc).
  then(function(doc) {
    // doc.events[0] has an 'element' property, doc.events[1] has a 'product' property
  });

[tomasdev]

Most use cases of this, can actually be simplified using multiple properties. For example, instead of

personas: [typeA | typeB]
 ```
you could do

personasTypeA: [typeA],
personasTypeB: [typeB]
```

In my case, it was files and folders (instead of having a flattened array of mixed file/folder, just separated them and I've let folders be recursive)

[r3wt]

@vkarpov15 will discrimantors work with a typed field such as in the following schema?

const TypesSchema = new Schema({ 
  type: {type:Number,enum:Object.values(constants.TYPES)} 
},{descriminatorKey:'type',_id:false});

I want to have a field called type with with types defined by the constants objects, and this field will be used to descriminate among the types schemas. each type has its own schema

[vkarpov15]

@r3wt I believe so. However, you should use type: String, because type: Number doesn't support enum

[r3wt]

@vkarpov15 i can't use String, because the constant values are int and strict equality is used everywhere. I just removed the enum for now

[vkarpov15]

@r3wt we'll have enum for numbers in 5.8.0, see #8139

[r3wt]

@r3wt we'll have enum for numbers in 5.8.0, see #8139

I appreciate it, but there was no way around it so we we ended up migrating all codebase to String and it is working without any issue now. I am glad to see this feature though, now i can save disk space by using more numeric enums for hardcoded values

[bbhopesh]

= 4.8.0 supports this:

var eventSchema = new Schema({ message: String },
  { discriminatorKey: 'kind', _id: false });

var batchSchema = new Schema({ events: [eventSchema] });
batchSchema.path('events').discriminator('Clicked', new Schema({
  element: String
}, { _id: false }));
batchSchema.path('events').discriminator('Purchased', new Schema({
  product: String
}, { _id: false }));

var MyModel = db.model('gh2723', batchSchema);
var doc = {
  events: [
    { kind: 'Clicked', element: 'Test' },
    { kind: 'Purchased', product: 'Test2' }
  ]
};
MyModel.create(doc).
  then(function(doc) {
    // doc.events[0] has an 'element' property, doc.events[1] has a 'product' property
  });

Hey @vkarpov15, I can't call discriminator method on schema, I need to create the model first but your example above shows otherwise. Can you please clarify?

[mkovel]

@bbhopesh Yes, you right Schema does have method discriminator, but
batchSchema.path('events') returns not a Schema, it method actually returns Schema | DocumentArrayPath. But @types/mongoose does not have right declaration, i guess.

You can find more info here

[vkarpov15]

@mkovel is correct, you can call discriminator() on certain schema types. FWIW batchSchema.path('events') does NOT return a schema, it returns a SchemaType