MongoDB - Spring Data fetch documents containing only requested fields(no more no less)

Question

I am using MongoDB with Spring Boot 2.0 and Spring Data. I have the following request to MongoDB

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "parameters": [
         {
            "name": "test-param-name1",
            "value": "test-param-value1"
         }
    ]
}

In MongoDB, for example I have following documents:

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "body" : "<response><rating>0.5</rating></response>",
    "parameters": [
      {
         "name": "test-param-name1",
         "value": "test-param-value1"
      },
      {
         "name": "test-param-name2",
         "value": "test-param-value2"
      }
     ]
}

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "body" : "<response><rating>0.5</rating></response>",
    "parameters": [
         {
            "name": "test-param-name1",
            "value": "test-param-value1"
         }
    ]
}

In my response I want to see only one document that strictly respond to the request search parameters and it have to be:

{
    "cra": "test-cra",
    "service": "test-service",
    "timestamp": "2012-04-23T18:25:43.511Z",
    "body" : "<response><rating>0.5</rating></response>",
    "parameters": [
             {
                 "name": "test-param-name1",
                 "value": "test-param-value1"
             }
    ]
}

Can I, with the help of Spring Data, build the query for getting only documents that strictly respond to my request fields (not with more or less fields)?

Answer 1

You can use MongoOperations, AggregationOperation and Aggregation to search on in array as follows:

    ApplicationContext ctx = new AnnotationConfigApplicationContext(MongoConfig.class);
    MongoOperations mongoOperation = (MongoOperations) ctx.getBean("mongoTemplate"); 

    AggregationOperation match = Aggregation.match(Criteria.where("cra").is("test-cra"));
    AggregationOperation unwind = Aggregation.unwind("parameters");
    AggregationOperation match2 = Aggregation.match(Criteria.where("parameters.value1").is("test-param-value1"));


    Aggregation aggregation = Aggregation.newAggregation(match, unwind, match2);

    AggregationResults<AggregateFactoryResult> output = mongoOperation.aggregate(aggregation, "tablename", AggregateFactoryResult.class);