How do I get all matching sub array Objects in mongoDB

Question

I have following JSON

[
  {
    "_id": "5c87e621257db42508007f3b",
    "uuid": "8b03dba7-db96-40d0-8dd9-6a65efd6719a",
    "user_answers": [
      {
        "profile_section_code": "MY_PROFILE",
        "profile_question_code": "STANDARD_EDUCATION",
        "selected_answer": [
          "2"
        ]
      },
      {
        "profile_section_code": "MY_PROFILE",
        "profile_question_code": "ETHNICITY",
        "selected_answer": [
          "2"
        ]
      },
      {
        "profile_section_code": "FAMILY",
        "profile_question_code": "STANDARD_HHI_US",
        "selected_answer": [
          "11"
        ]
      },
      {
        "profile_section_code": "FAMILY",
        "profile_question_code": "STANDARD_HH_ASSETS",
        "selected_answer": [
          "5"
        ]
      },
      {
        "profile_section_code": "AUTOMOTIVE",
        "profile_question_code": "STANDARD_AUTO_DECISION_MAKER",
        "selected_answer": [
          "1"
        ]
      }
    ],
    "created_at": "2019-03-12T17:02:25.000Z"
  }
]

Complete JSON can be seen here: Link

I want to fetch all user_answers with "profile_section_code": "MY_PROFILE" Expected Result should be like this

{ "_id": "5c87e621257db42508007f3b", "uuid": "8b03dba7-db96-40d0-8dd9-6a65efd6719a", "user_answers": [ { "profile_section_code": "MY_PROFILE", "profile_question_code": "STANDARD_EDUCATION", "selected_answer": [ "2" ] }, { "profile_section_code": "MY_PROFILE", "profile_question_code": "ETHNICITY", "selected_answer": [ "2" ] }],"created_at": "2019-03-12T17:02:25.000Z" }

I tried $elemMatch in Projection but it returns the only 1st Matching array, I need something just like $elemMatch but should return all matching array. here's Fiddle for the same

I also tried using this Answer But it didn't work as it was returning only 1st matching subArray

Is there any way to do this using Projection only (I want to avoid Aggregation, as I have to implement this in PHP)
If Above is not possible then how can I implement this using aggregate?

Please let me know what I can do to fix this

Please refer https://stackoverflow.com/questions/3985214/retrieve-only-the-queried-element-in-an-object-array-in-mongodb-collection — Mani, Mar 12 '19 at 20:30

Mani · Accepted Answer · 2019-03-12T20:34:21.810

3

Use $filter to get your expected result. Also, it looks like aggregation pipeline is the only option to filter the records or it needs to be done at PHP code level.

[
    {
        '$addFields': {
            'user_answers': {
                '$filter': {
                    'input': '$user_answers', 
                    'as': 'user_answer', 
                    'cond': {
                        '$eq': [
                            '$$user_answer.profile_section_code', 'MY_PROFILE'
                        ]
                    }
                }
            }
        }
    }
]

edited Mar 12 '19 at 20:34

answered Mar 12 '19 at 20:26

Mani

1,471
1
13
19

Thanks It worked. One more help is needed - May I know if I have a heavy document, which would be better in this case Aggregation or Filtering through PHP. I understand its a Vague question because of various factors still what do you think? – Pankaj Jha Mar 13 '19 at 08:49
1

I would say, aggregation is the better option compared to doing it in PHP, because the aggregation framework filters the records from MongoDB and sends only the filtered records to the code but the other way all data sent to code and which is costlier than aggregation framework. – Mani Mar 13 '19 at 20:39

How do I get all matching sub array Objects in mongoDB

1 Answers1