Schema.path() always returns SchemaType and not the specific type of the supplied path

[satyamtg]

Prerequisites

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

Mongoose version

6.4.0

Node.js version

16.8.0

MongoDB server version

5.x

Description

When I try to run Schema.path() on a mongoose Schema, I always get the result as SchemaType. However, in the types, I see many specific classes that extend SchemaType and have extra methods such as discriminator. I don't know if I'm doing something wrong, but I assume that TypeScript won't throw errors if correct SchemaType is sent as the resultant type of path()

Steps to Reproduce

Sample code to reproduce -

import { Schema, model, SchemaType, Document, Model, Types, SchemaTypes } from 'mongoose';

interface IUser {
	name: string;
	email: string;
	organization: Types.ObjectId;
 }
 
 const userSchema = new Schema<IUser>({
	name: { type: String, required: true },
	email: { type: String, required: true },
	organization: { type: Schema.Types.ObjectId, ref: 'Organization' }
  });

const pathResult = userSchema.path('name'); // I always get SchemaType as the result

[RAY-EZ]

I also found this a bit confusing at first. But mongoose defines the path with the given Predefined Types eg String, Number, ObjectID.
mongoose.prototype.path here in example
they have passed second argument as Number. I also thought it should return Number while calling schema.path('path'). Calling schema.path('fullpath', Number) this creates a new path with name instance of SchemaNumber.

Anyway if you want get specific type out of SchemaType schema.path('parent.child').instance

[satyamtg]

@RAY-EZ can you please elaborate a bit with a code example? I do know there is a getter and a setter for path. However, can you explain what you mean by fullpath and then parent.child. Also, I get this TS error while using .instance as you suggested -

Property 'instance' does not exist on type 'SchemaType'.ts(2339)

[RAY-EZ]

@satyamtg I have tried every way to reproduce error. I think your typescript acting up restarting ts-server might help..

        ...
	name: { 
          firstName: {
               type: String, required: true 
               },
         lastName: {
         ...
  });

const pathResult = userSchema.path('name');

I modified your example a bit. suppose you have nested Path, like name has firstName. Now to access SchemaType
you would pass fullpath i.e name.firstName.

workaround to satisfy typescript
const pathResult = userSchema.path('name') as SchemaType<IUser>
I hope it works 🙂

[vkarpov15]

In 6.4.3 you'll be able to do userSchema.path<'name'>('name') to get back SchemaType<string>