Mongoose: Virtuals Populate options for sort / limit

[siboulet]

Thanks for this great new feature! Virtuals Populate are very useful in our case to dynamically populate from a TTL collection.

One issue though is it seems its not possible to limit the documents that are populated.

Suppose we have a User collection where user sessions are stored in a separate TTL collection. I want the 5 most recent sessions to be populated:

userSchema.virtual('sessions', {
  ref: 'Session',
  localField: '_id',
  foreignField: 'user',
  options: { sort: { date: -1 }, limit: 5 },
});

Currently it seems there is no way to pass the options.

Thanks

[vkarpov15]

Yeah right now you'd need to specify the options in the populate call itself, no support for options in virtual populate schema definition

```javascript
User.findOne().populate({ path: 'sessions', options: { sort: { date: -1 }, limit: 5 });
````