How to find Distinct Data in MongoRepository-CodePudding

How to write Custom Query for Mongo DB to get the distinct data Need to write in Java but I need to check if is it possible with the query as well without using aggregation pipeline. Sample Data:

[
   {
      "id":1,
      "empName":"emp1",
      "emp_city":"city1"
   },
   {
      "id":2,
      "empName":"emp2",
      "emp_city":"city1"
   },
   {
      "id":3,
      "empName":"emp1",
      "emp_city":"city1"
   },
   {
      "id":4,
      "empName":"emp1",
      "emp_city":"city2"
   }
]

Expected Output:

[
   {
      "empName":"emp1",
      "emp_city":"city1"
   },
   {
      "empName":"emp1",
      "emp_city":"city2"
   },
   {
      "empName":"emp2",
      "emp_city":"city1"
   }
]

CodePudding user response：

For what you are trying to archive I would suggest using a group by, by the two fields (empName and emp_city),

Here you have and example https://sqlserverguides.com/mongodb-group-by-multiple-fields/

CodePudding user response：

use this :

db.collection.aggregate([
  {
    $group: {
      _id: {
        empName: "$empName",
        emp_city: "$emp_city"
      }
    }
  },
  {
    "$replaceRoot": {
      "newRoot": "$_id"
    }
  }
])

https://mongoplayground.net/p/d8i7iOuvfsR