How to hide the selected field which is necessary for the virtual field in the result data

[secreter]

In my case, I have a User schema and a Post schema, I want to populate a virtual field 'name' in User to the Post, when the 'nickname' is empty, use '**' concat the part of 'phoneNumber'。And never expose the 'phoneNumber' in post data。 But I find it difficult to achieve。Without selecting the 'phoneNumber' field, can't get the correct 'name'。 I need some help,Thanks.

// this is the user schema
const UserSchema = new mongoose.Schema(
    {
      nickname: {
        type: String
      },
      phoneNumber: {
        type: String,
      }
    },
    {
      toJSON: { virtuals: true },
      toObject: { virtuals: true }
    }
  );
// user may not set nickname, use '*' and part of phoneNumber
UserSchema.virtual('name').get(function() {
  return this.nickname||'**'+this.phoneNumber?.slice(-4);
});

In the Post schema , I want to auto populate the 'user' field，I expect return the name field and hide the phoneNumber field，but it seems can't achieve。

// only select 'name  ', hide 'phoneNumber'
{
    autopopulate: {
      select: 'nickname',
    }
}

In this case，the post.user.name return '**undefined'。 when I add the 'phoneNumber' field it works, but how can I hide the 'phoneNumber' field?

{
    autopopulate: {
      select: 'nickname phoneNumber',
    }
}

In this case，the post.user.name return 'Bob'。

[vkarpov15]

'name' is a virtual, not a field. You can't select: 'name'. You should do select: 'nickname' instead.

[secreter]

Sorry, it's a typo, I finally want the name virtual in Post data，and never expose the 'phoneNumber' in post data。

// user may not set nickname, use '*' and part of phoneNumber
UserSchema.virtual('name').get(function() {
  return this.nickname||'**'+this.phoneNumber?.slice(-4);
});

[vkarpov15]

Your best bet would be to add a getter that obfuscates the phone number. Something like:

const UserSchema = new mongoose.Schema(
    {
      nickname: {
        type: String
      },
      phoneNumber: {
        type: String,
        get(v) { return v == null ? v : v.slice(-4); }
      }
    },
    {
      toJSON: { virtuals: true },
      toObject: { virtuals: true }
    }
  );

More info on getters and setters in Mongoose: https://mongoosejs.com/docs/tutorials/getters-setters.html