InferSchemaType returns unknown value

[imranbarbhuiya]

Prerequisites

• I have written a descriptive issue title
• I have searched existing issues to ensure the bug has not already been reported

Mongoose version

>=8.0.2

Node.js version

20

MongoDB server version

Not needed

Typescript version (if applicable)

5.3.3

Description

I was updating Mongoose and found all the prop values of the schema types became unknown so I tried to check previous versions and found it's starting from 8.0.2, after checking commits and reverting them, and found this pr is causing the issue. It happens when the array of objects has a type as a prop, and also if the schema has a prop with the value SchemaTypes.Array. Using new Schema for subdocument fixes this but causes another issue with lean type for arrays, will create a new issue for that

Steps to Reproduce

export const UserSchema = new Schema(
    {
        reminders: {
            type: [
                {
                    type: { type: SchemaTypes.String },
                    date: { type: SchemaTypes.Date },
                    toggle: { type: SchemaTypes.Boolean },
                    notified: { type: SchemaTypes.Boolean },
                },
            ],
            default: [
                { type: 'vote', date: new Date(), toggle: false, notified: false },
                { type: 'daily', date: new Date(), toggle: false, notified: false },
                { type: 'drop', date: new Date(), toggle: false, notified: false },
                { type: 'claim', date: new Date(), toggle: false, notified: false },
                { type: 'work', date: new Date(), toggle: false, notified: false },
            ],
        },
        avatar: {
            type: SchemaTypes.String,
        },
    },
    { timestamps: true },
);

export type IUser = InferSchemaType<typeof UserSchema>;

Lemme know if I'm doing anything wrong with the schema. Or if it's a bug, I'll be happy to contribute, lemme me know how can I fix it.

Expected Behavior

It should give proper typings like before

_Originally posted by @imranbarbhuiya in #14095 (comment)

[vkarpov15]

You're right, this is due to the type: { type: SchemaTypes.String } property. Without type, everything compiles fine. We're investigating

[imranbarbhuiya]

You're right, this is due to the type: { type: SchemaTypes.String } property. Without type, everything compiles fine. We're investigating

the issue with nested type is fixed but now all the arrays are DocumentArray so I cant pass a normal array to this type, can't use .includes with normal types

export const UserSchema = new Schema({
	languages: [
		{
			name: SchemaTypes.String,
			spoken: SchemaTypes.Boolean,
		},
	],
	roles: [SchemaTypes.String],
});

export type IUser = InferSchemaType<typeof UserSchema>;

const a: IUser = {
	languages: [
		{
			name: 'English',
			spoken: true,
		},
	],
};

// Type '{ name: string; spoken: true; }' is not assignable to type 'Subdocument<ObjectId> & { name?: string | null | undefined; spoken?: boolean | null | undefined; }'.
//  Type '{ name: string; spoken: true; }' is missing the following properties from type 'Subdocument<ObjectId>': $isSingleNested, ownerDocument, parent, $parent, and 50 more.ts(2322)
// types.d.ts(63, 11): The expected type comes from property '0' which is declared here on type 'DocumentArray<{ name?: string | null | undefined; spoken?: boolean | null | undefined; }>'

a.roles.includes('a');
// Argument of type 'string' is not assignable to parameter of type 'Subdocument<ObjectId> & { get?: {} | null | undefined; set?: {} | null | undefined; prototype?: string | null | undefined; schemaName?: string | null | undefined; cast?: {} | ... 1 more ... | undefined; checkRequired?: {} | ... 1 more ... | undefined; }'.
//  Type 'string' is not assignable to type 'Subdocument<ObjectId>'.ts(2345)

[pavel-luhin]

Hi @imranbarbhuiya
Have you found any workaround? Mine is to pass object with array directly to create function. Maybe you found something else?

[vkarpov15]

We have a PR to fix a.roles.includes('a'); #14534.

For const a: IUser = { ... } that's unfortunately currently expected behavior. We'll bump up #13900 in priority, which will add a separate helper than can infer the raw document type, rather than inferSchemaType<>, which is meant to be more of an internal helper for Mongoose to figure out the hydrated document type.