Spring Boot return only one random document from MongoDB Collection

Question

Imagine I have three documents in collection:

First one is:

Title: Myanmar
Category: escortedTours

Second one is:

Title: Barcelona
Category: independentTours

Third one is:

Title: Spain
Category: escortedTours

Now I want to create a method that will return me just ONE RANDOM document with category as escortedTours . So for every refresh page program need to return me one random document with escortedTours .

I create something like this but this return me all documents with category as escortedTours while I need one random element on every refresh.

Repo:

List<PackageHoliday> findByTypeOfPackageHoliday(String typeOfPackageHoliday);

ServiceImpl:

 @Override
public List<PackageHoliday> findByTypeOfPackageHoliday(String typeOfPackageHoliday) {
    return packageHolidayRepository.findByTypeOfPackageHoliday(typeOfPackageHoliday);
}

And controller:

  @GetMapping("/getEscortedTours")
public List<PackageHoliday> getByPackageHoliday() {
    return packageHolidayService.findByTypeOfPackageHoliday("escortedTours");
}

What and where I need to add/create so this will return me just one random document from collection with category as escortedTours

Answer 1

Try the $sample operator:

db.PackageHoliday.aggregate([
  {
    "$match": {
      Category: "escortedTours"
    }
  },
  {
    $sample: {
      size: 1
    }
  }
])

MongoPlayground