java.lang.IllegalArgumentException: Expected unique result or null, but got more than one! - Spring Data Mongo

Question

I\'m usingSpring Boot v2.2.2.RELEASE and Spring Data MongoDB. In this example, I am looking perform group by department code and get all employees

Answer 1

Aggregations on repository methods do not support the Page return type. Please have a look at the Reference Documentation for supported return types (eg. List).

I created DATAMONGO-2506 to improve the error message in that case.

Answer 2

At least I was able to get the data with below query, but still struggling to make the data in the form of Pages

db.country.aggregate([
  {
    $group: {
      _id: "$departments.deptCd", matches: { $push: '$$ROOT' }
    },
    $facet: {}
  }
])

Reference from : Keeping field in mongodb group by and how to group in mongoDB and return all fields in result