Mongo DB request in Java Spring-data Mongo

Question

I have an array inside of document.

{
    "id" : "id_1",
    "name" : "name_1";
    "additionalData" : [
        {
             "additionalDataId" : "id_1_1",
             "additionalDataName" : "name_1_1",
             "longText" : "A long story about..."  
        },
        {
             "additionalDataId" : "id_1_2",
             "additionalDataName" : "name_1_2",
             "longText" : "A longer story about danger..."  
        },
        {
             "additionalDataId" : "id_1_3",
             "additionalDataName" : "name_1_3",
             "longText" : "A longer story about danger and courage"  
        },
    ]       
}

To retrieve element of array with name "name_1_2", I use mongo query.

db.collection.find( { name: "name_1"},
        { _id: 0, additionalData: { $elemMatch: { "additionalDataName": "name_1_2" } } 
    })

How to do the same using mongoTemplate?

I have tried

Aggregation aggregation = Aggregation.newAggregation(
    Aggregation.match(
            Criteria.where("name").is("name_1").and("additionalData.additionalDataName").is("name_1_2")
        ),
    Aggregation.project("additionalData"),

); mongoTemplate.aggregate(aggregation, "CustmObjects", Object.class);

And I also tried to use ArrayOperators.Filter.filter, I used this answer.

Aggregation aggregation = Aggregation.newAggregation(
        Aggregation.match(Criteria.where("name").is("name_1")),
        Aggregation.project("additionalData").and(
                ArrayOperators.Filter.filter("additionalData").as("item")
                        .by(ComparisonOperators.valueOf("item.additionalDataName").equalTo("name_1_2"))
        )
    );
mongoTemplate.aggregate(aggregation, "CustmObjects", Object.class);

https://stackoverflow.com/a/46769125/4587961

Anyway, the result I got, all elements of the array. Please, help!

$elemMatch projection is not available in aggregate(). Use a .find variant instead, or $filter just as demonstrated in the answers you link to. — Neil Lunn
– Neil Lunn, Commented Mar 5, 2019 at 23:47
I will write in 9 hours. Not at work now. It did not work with Aggregate and ArrayOperators.Filter — Yan Khonski
– Yan Khonski, Commented Mar 5, 2019 at 23:51
Okay, better to actually show what you tried so we can point out what exactly you did wrong anyway. Though I thought I did previously link you to a spring-mongo implementation of exactly that $filter usage. So a bit unsure what part you did not get right. Either that or I linked the wrong example :( — Neil Lunn
– Neil Lunn, Commented Mar 5, 2019 at 23:54

Mher Davtyan · Accepted Answer · 2020-05-07 08:17:33Z

1

If I understood the question correctly, this will give the desired results.

Query query = new Query(new Criteria().andOperator(
    Criteria.where("name").is("name_1"),
    Criteria.where("additionalData.additionalDataName").is("name_1_2")
));
query.fields().include("additionalData").exclude("_id");

List<Document> results = template.find(query, collectionName, org.bson.Document.class);

edited May 7, 2020 at 8:17

answered Apr 17, 2020 at 13:15

Mher Davtyan

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1 Comment

Coder17 Over a year ago

This is giving a list but question is to fetch this object - { "additionalDataId" : "id_1_2", "additionalDataName" : "name_1_2", "longText" : "A longer story about danger..." }

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