Mongodb select particular element form an nested document

Question

I have below MongoDB object structure. I would like to select aclpermissions based on values (using Spring MogoTemplate). e.g. if I pass "58dc0bea0cd182789fc62fab" it should return only aclpermissions.READ but if I pass "58dc0bd70cd182789fc62faa" it should return all the aclpermissions.

How to achieve that. if I have to modify data structure please suggests what to do and how to achieve that.

{
        "_id" : ObjectId("5900d6abb9eb284a78f5a350"),
        "_class" : "com.debopam.amsapp.model.AMSAppACL",
        "attrUniqueCode" : "USER",
        "attributeVersion" : 1,
        "aclpermissions" : {
                "CRT" : [
                        "58dc0bd70cd182789fc62faa"
                ],
                "READ" : [
                        "58dc0bd70cd182789fc62faa",
                        "58dc0bea0cd182789fc62fab"
                ],
                "UPD" : [
                        "58dc0bd70cd182789fc62faa"
                ],
                "DLT" : [
                        "58dc0bd70cd182789fc62faa"
                ]
        },
        "orgHierachyIdentifier" : "14",
        "orgid" : 14,
        "createDate" : ISODate("2017-04-26T17:19:39.026Z"),
        "lastModifiedDate" : ISODate("2017-04-26T17:19:39.026Z"),
        "createdBy" : "appadmin",
        "lastModifiedBy" : "appadmin"
}

Community · Accepted Answer · 2017-05-23 12:34:23Z

1

You can use the same updated structure from Mongodb Search nested array elements

You can use the below aggregation query with $filter array operator with $setIsSubset query operator, which compares and selects the nested document where input value is a subset of aclpermission.v.

 import static org.springframework.data.mongodb.core.aggregation.ArrayOperators.Filter.filter;
 import static org.springframework.data.mongodb.core.aggregation.Aggregation.*;
 import static java.util.Arrays.asList;

  Aggregation aggregation = newAggregation(
          match(Criteria.where("_id").is(new ObjectId("5900d6abb9eb284a78f5a350"))),
          project()
               .and(filter("aclpermissions")
                                .as("aclpermission")
                                .by(aggregationOperationContext -> new BasicDBObject("$setIsSubset", asList(asList("58dc0bd70cd182789fc62faa"), "$$aclpermission.v"))))
         .as("aclpermissions")
  );

 List<BasicDBObject> results = mongoTemplate.aggregate(aggregation, collectionName,  BasicDBObject.class).getMappedResults();

Mongo Shell query:

aggregate([ { "$match" : { "_id" : ObjectId("5900d6abb9eb284a78f5a350")}} , { "$project" : { "aclpermissions" : { "$filter" : { "input" : "$aclpermissions" , "as" : "aclpermission" , "cond" : { "$setIsSubset" : [ ["58dc0bd70cd182789fc62faa"], "$$aclpermission.v"]}}}}}])

Update:

The below query will $match documents with attrUniqueCode value equal to USER followed by $sort and $group the pick the latest document. $$ROOT is expression variable to access the whole document with $first to get the latest one.

 Aggregation aggregation = newAggregation(
         match(Criteria.where("attrUniqueCode").is("USER")),
         sort(new Sort(Sort.Direction.DESC, "attributeVersion")),
         group().first("$$ROOT").as("latest"),
         project("latest._id", "latest.attrUniqueCode", "latest.attributeVersion")
                        .and(filter("latest.aclpermissions")
                                .as("aclpermission")
                                .by(aggregationOperationContext -> new BasicDBObject("$setIsSubset", asList(asList("58dc0bd70cd182789fc62faa"), "$$aclpermission.v"))))
         .as("aclpermissions")
  );

Reference

https://docs.mongodb.com/manual/reference/aggregation-variables/ https://docs.mongodb.com/manual/reference/operator/aggregation/project/ https://docs.mongodb.com/manual/reference/operator/aggregation/filter/

edited May 23, 2017 at 12:34

CommunityBot

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answered Apr 28, 2017 at 17:54

s7vr

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5 Comments

Debopam Over a year ago

Thanks. Will test this and let you know.

Debopam Over a year ago

This works. but as I asked in stackoverflow.com/questions/43667611/… could you please let know how to integrate that. Considering for a "attrUniqueCode" there can be multiple "attributeVersion". How to select latest one i.e. record with the highest version.

s7vr Over a year ago

You are welcome. Updated to include the filter from the other post. See if it helps.

Debopam Over a year ago

Thanks it worked. But could you please explain to me what is happening here. $$ROOT, Project and filter etc.

s7vr Over a year ago

You are welcome. Add some more description and links

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