Convert mongodb shell command to java code

Question

I'm new in mongodb and spring, i need to convert the following query to java code but i didn't find how to do it.

db.collection.aggregate([
{
  $project: {
    members: {
      $concatArrays: [
        [
          {
            "userID": "$userID",
            "userType": "$userType"
          }
        ],
        {
          $reduce: {
            input: "$clients",
            initialValue: [],
            in: {
              $concatArrays: [
                "$$value",
                [
                  {
                    userID: "$$this.userID",
                    userType: "$$this.userType"
                  }
                ],
                "$$this.members"
              ]
            }
          }
        }
      ]
    }
  }
},
{
  $unwind: "$members"
},
{
  $replaceRoot: {
    newRoot: "$members"
  }
}
])

I m stack in the $project part, i didn't find how to implement it in spring. Can someone help me?

Rajat Goel · Accepted Answer · 2019-07-19 06:05:43Z

1

For use cases, where you find it hard to write a query in spring MongoDB java format, You can use the JSON/JavaScript code directly like this:

String jsonExpression = "{\"members\":{\"$concatArrays\":[[{\"userID\":\"$userID\",\"userType\":\"$userType\"}],{\"$reduce\":{\"input\":\"$clients\",\"initialValue\":[],\"in\":{\"$concatArrays\":[\"$$value\",[{\"userID\":\"$$this.userID\",\"userType\":\"$$this.userType\"}],\"$$this.members\"]}}}]}}";
AggregationOperation project = Aggregation.project().and(context -> context.getMappedObject(Document.parse(jsonExpression))).as("difference");

You can refer to my other answer here : Difference between "now" and a given date

answered Jul 19, 2019 at 6:05

Rajat Goel

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