Populate a query in Mongoose with Schema First approach and NestJS

Question

First off I want to say this question is similar to this one which references this one. I have the exact same question as the second link except a notable difference. I'm trying to extend a class generated by NestJS which defines a property.

I'm using NestJs with the Schema first approach found here. I'm also generating a classes file based on my GraphQL Schema.

Here is the Schema:

type Location {
  name: String!
  owner: User!
}

Which generates the class:

export class Location {
    name: string;
    owner: User;
}

Now, I want to extend this class so I don't have to repeat the data (there are a lot more fields not shown). I also I want to add fields that live on a document but are not in the schema (_id in this example). Here is my LocationDocument and my schema.

export interface LocationDocument extends Location, Document {
  _id: Types.ObjectId
}

export const LocationSchema: Schema = new Schema(
  {
    name: {
      type: String,
      required: true,
    },
    owner: {
      type: Types.ObjectId,
      ref: 'User',
    }
);

Now here is my issue. The generated Location class from the GraphQL schema defines the owner property as a User type. But in reality it's a just a mongodb id until it is populated by Mongoose. So it could be a Types.ObjectId or a User on a UserDocument. So I attempted to define it as:

export interface LocationDocument extends Location, Document {
  _id: Types.ObjectId
  owner: User | Types.ObjectId;
}

But this throws an error in the compiler that LocationDocument incorrectly extends Location. This makes sense. Is there any way to extend the User Class but say that owner property can be a User Type (once populated by Mongoose) or a mongo object ID (as is stored in the database).

Diesel Diesel · Accepted Answer · 2019-07-17T13:11:20

I decided that having a property that can be both types, while easy with Mongoose and JS, isn't the typed way. In my schema I have an owner which is a User type. In my database and the document which extends it, I have an OwnerId. So to people accessing the API, they don't care about the ownerId for the relationship. But in my resolver, I use the Id. One is a Mongo ID type, the other is a User type.

Populate a query in Mongoose with Schema First approach and NestJS

1 Answers