How to use $objectToArray in SpringMongo?

Question

In the following query, I'm trying to use $objectToArray mongo aggregated function in a SgringMongo. Can someone help me, please?

I couldn't find any way to convert it to a SpringMongo query

db.getCollection('application').aggregate([
    {$project: {
        people: {$objectToArray: '$applicants.people'},
        doc: '$$ROOT'
        }
    },
    {$match:{'people.v.personName.firstName':  /.*ad.*/i, 'people.v.disabled': true}},
    {$replaceRoot: {newRoot: '$doc'}}
])

Answer 1

In short this is the way:

var aggregation = newAggregation(
   Application.class,
   project().and(ObjectOperators.valueOf("applicants.people")
            .toArray())
            .as("people"));

mongoTemplate.aggregate(aggregation, Application.class, OutputModel.class);

it will generate for you an aggregation with following stage:

[
    {
      "$project": {
        "people": {
          "$objectToArray": "$applicants.people"
        }
      }
    }
]

DETAILS

Assume that you have following model:

@Document(collection = "application")
@TypeAlias(alue = "application")
@AllArgsConstructor // lombok annotation
public class Application {
  String id;
  Applicants applicants;

  @Value  // lombok annotation
  public static class Applicants {
    Map<String, Person> people;
  }

  @Value
  public static class Person {
    PersonName personName;
    boolean disabled;
  }

  @Value
  public static class PersonName {
    String firstName;
    String lastName;
  }
}

Example of documents in MongoDB for above can be:

{
    "_id" : "id-1",
    "applicants" : {
        "people" : {
            "person1" : {
                "personName" : {
                    "firstName" : "Ziemowit",
                    "lastName" : "Stolarczyk"
                },
                "disabled" : true
            },
            "person2" : {
                "personName" : {
                    "firstName" : "Denio",
                    "lastName" : "Pimentel"
                },
                "disabled" : false
            }
        }
    },
    "_class" : "application"
}

Generated projection by code from top will give you as an output:

{
    "_id" : "id-1",
    "people" : [
        {
            "k" : "person2",
            "v" : {
                "personName" : {
                    "firstName" : "Denio",
                    "lastName" : "Pimentel"
                },
                "disabled" : false
            }
        },
        {
            "k" : "person1",
            "v" : {
                "personName" : {
                    "firstName" : "Ziemowit",
                    "lastName" : "Stolarczyk"
                },
                "disabled" : true
            }
        }
    ]
}

Answer 2

Try:

Document doc = new Document ("people", ObjectOperators.valueOf("$applicants.people").toArray().toDocument(Aggregation.DEFAULT_CONTEXT));

it will give as:

{"people": {$objectToArray: '$applicants.people'}}