java - MongoDB - spring data - how to pick objects from different arrays into array / list

Question

Object sample:

[
    {
        "name": "aaa",
        "list": [
            {
                "key": "val1"
            },
            {
                "key": "val2"
            },
            {
                "key": "val3"
            },
            {
                "key": "val4"
            }
        ]
    },
    {
        "name": "bbb",
        "list": [
            {
                "key": "val2"
            },
            {
                "key": "val4"
            },
            {
                "key": "val6"
            },
            {
                "key": "val8"
            }
        ]
    }
]

Query: list.key = val1 or val6

Actual results:

[
{"key":"val1"},
{"key":"val2"},
{"key":"val3"},
{"key":"val4"},
{"key":"val2"},
{"key":"val4"},
{"key":"val6"},
{"key":"val8"}
]

Expected results:

[
{"key":"val1"},
{"key":"val6"}
]

I need to pick all objects in list that equal to criteria.

@Query(value="{$or :{ 'listKey' : ?0},{ 'listKey' : ?1} }", fields="{ 'listKey' : 1}")
    public List<Object> findByListKey(String value,String value2); // val1 or val6 

Actually, it retrieves all objects of list in case it contains this value.

Any suggestions?

Answer 1

You need to project array documents using $ operator & for that you need to use $elemMatch in query.

Use this query

@Query(value="{ list: {$elemMatch: {$or: [{ 'key': ?0 }, { 'key': ?1 }]}}}", fields="{ 'list.$':1}")