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This is a document I want to search. Collection is CustmObjects. This is one CustomObject

{
    "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 a document with name name_1 is easy.

final nameToSearchBy = "name_1";

Query query = new Query();
Criteria criteria = Criteria.where("name").is(nameToSearchBy);
query.addCriteria(criteria);
mongoTemplate.findOne(query, CustomObject.class, "CUSTOM_OBJECTS_COLLECTION");

Now my question. How to retrieve additionalData with name "id_1_2"? I do not need to retrieve the whole document, only an entry in the array.

Of course, I can retrive a whole document and iterate through its additionalData values in java program. But I want to delegate this job to database server.

I 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);

It returns all elements of the array. I need only one matching element.

Update

This is what I want to do Retrieve only the queried element in an object array in MongoDB collection

db.find({shapes: {"$elemMatch": {name: "name_1_2"}}}, ... )

As I understand, what the second part is projection to select fields. I need all the fields from array element.

{"shapes.color": 1}

The second link Spring data Match and Filter Nested Array

The result I want to get is this

{
     "additionalDataId" : "id_1_2",
     "additionalDataName" : "name_1_2",
     "longText" : "A long story about..."  
}

is more comlex, it has array inside of element which is inside of array. Please, I need something more simple and working.

Yan Khonski
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    can you provide more details : Do you want to retrieve whole documents where at least one array element have "additionalDataName" : "name_1_2", or do you want to ertrieve only entry of array that matches that condition? – matthPen Mar 05 '19 at 12:44
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    here's the query in js : db.collection.find( { name: "name_1"}, { _id: 0, additionalData: { $elemMatch: { "additionalDataName": "name_1_2" } } }) – matthPen Mar 05 '19 at 22:04
  • 1
    open a new question : "how to translate this in java / spring boot?" Cannot answer here. – matthPen Mar 05 '19 at 23:15
  • Please, https://stackoverflow.com/questions/55013224/mongo-db-request-in-java-spring-data-mongo – Yan Khonski Mar 05 '19 at 23:28

0 Answers0