How can I filter sub-documents from MongoDB with SpringBoot?

Question

I have documents in a collection such as :

{
  "login":"xxx",
  "someAttribute":"someValue",
  "subDocs":[
    {
      "data": "val1",
      "subDocNestedArray":["WWW","AAAA"]
    },
    {
      "data": "val2",
      "subDocNestedArray":["AAAA"]
    },
    {
      "data": "val3",
      "subDocNestedArray":["ZZZ"]
    }
    ]
}

I retrieve all documents that match login="xxx" and subDocNestedArray="AAAA" but want only subDocs matching along other properties of the root document, ex :

{
  "login":"xxx",
  "someAttribute":"someValue",
  "subDocs":[
    {
      "data": "val1",
      "subDocNestedArray":["WWW","AAAA"]
    },
    {
      "data": "val2",
      "subDocNestedArray":["AAAA"]
    }
    ]
}

I have tried with :

Aggregation.unwind("$subDocs"),
Aggregation.match(Criteria.where("subDocs.subDocNestedArray").is("AAAA")),
Aggregation.group("$_id")

that results in missing fields

{
  "login": null,
  "someAttribute": null,
  "subDocs":[
    {
      "data": "val1",
      "subDocNestedArray":["WWW","AAAA"]
    },
    {
      "data": "val2",
      "subDocNestedArray":["AAAA"]
    }
    ]
}

I did not manage to find the syntax using "redact".

Any clue ?

Make my MongoDB query return filtered results

What's the purpose of the $unwind and $group? Do you get the desired results if you only those stages completely? — user20042973, Jun 12 '23 at 14:30

score 1 · Answer 1 · answered Jun 13 '23 at 09:00

1

You can try this:

MatchOperation match = match(Criteria.where("login").is("xxx").and("subDocs.subDocNestedArray").is("AAAA"));
AddFieldsOperation addField = AddFieldsOperation.addField("subDocs").withValueOf(ArrayOperators.Filter.filter("subDocs").as("item").by(ArrayOperators.In.arrayOf("$$item.subDocNestedArray").containsValue("AAAA")));
Aggregation agg = Aggregation.newAggregation(match, addField);
AggregationResults<XYZClass> aggResults = mongoTemplate.aggregate(agg, "CollectionName",XYZClass.class);

In this, we have a $match stage to filter documents, and then an addFields stage, to filter the subDocs array. Please test it out.

answered Jun 13 '23 at 09:00

Charchit Kapoor

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Works fine, thank you. I discovered the Filter operator but did not understand its syntax., I had no idea of the AddFieldsOperation part – pibou Jun 14 '23 at 09:46
1

Filter creates an expression, whereas AddFields is an aggregation stage, it can add new fields to the document or update existing fields as well. @pibou – Charchit Kapoor Jun 14 '23 at 15:12

How can I filter sub-documents from MongoDB with SpringBoot?

1 Answers1