Populate type with TypeScript not working

Do you want to request a feature or report a bug? bug

What is the current behavior? property in interface with type PopulatedDoc<interface & Document> has type any If the current behavior is a bug, please provide the steps to reproduce.

import mongoose, { Schema, model, Document, PopulatedDoc } from 'mongoose';
async function run() {
    mongoose.connect('mongodb://localhost:27017/test');
    // `child` is either an ObjectId or a populated document
    interface Parent {
        child?: PopulatedDoc<Child & Document>,
        name?: string
    }
    const ParentModel = model<Parent>('Parent', new Schema<Parent>({
        child: { type: 'ObjectId', ref: 'Child' },
        name: String
    }));

    interface Child {
        name?: string;
    }
    const childSchema: Schema = new Schema<Child>({ name: String });
    const ChildModel = model<Child>('Child', childSchema);

    const parent = await ParentModel.findOne({}).populate('child')
    parent!.child.name;
}

{
  "compilerOptions": {
    "target": "ES6",                      
    "module": "commonjs",                     
    "strict": true,                          
    "esModuleInterop": true,                 
    "forceConsistentCasingInFileNames": true 
  }
}

What is the expected behavior? it should support the type of given interface What are the versions of Node.js, Mongoose and MongoDB you are using? Note that “latest” is not a version. Node.js: 14.17.4 , Mongoose: 6.0.7 , MongoDB: 4.4.3

[sheerlox]

@vkarpov15 I’m running in the same issue as @judgegodwins regarding the populate method returning an intersection type:

ParentModel.findOne({})
  .populate<{ child: Child }>('child')
  .orFail()
  .then((doc) => {
    const t: string = doc.child.name
  })

The type of doc.child in the callback is Types.ObjectId & Child, while we expect Child | null. (iirc the null type should be automatically added since Mongoose might return it if the document was not found).

Even when using .populate<{ child: Child | null }>('child'), doc.child stays Types.ObjectId & Child.

Typescript 4.2.4 / Mongoose 6.0.13

[ahmedelshenawy25]

@thiagokisaki using your example above, there’s still no name property on child.