MongoDB object property check if $exists with certain value in nested array - node.js

Question

I have a DB collection like this.
{
"name" : "test",
"gender" : "male",
"attributes" : [
{
"field_id" : "123",
"field_value" : "['Public']"
},
{
"field_id" : "124",
"field_value" : "true"
},
{
"field_id" : "125",
"field_value" : "['Single']"
},
]
},
{
"name" : "test2",
"gender" : "male",
"attributes" : [
{
"field_id" : "125",
"field_value" : "['Married']"
},
]
},
{
"name" : "test3",
"gender" : "male",
"attributes" : [
{
"field_id" : "123",
"field_value" : "['Public']"
},
{
"field_id" : "125",
"field_value" : "['Married']"
},
]
},
{
"name" : "test4",
"gender" : "male",
"attributes" : [
{
"field_id" : "123",
"field_value" : "['Private']"
},
]
},
{
"name" : "test4",
"gender" : "male",
"attributes" : [
]
}
]
I want to fetch all records which have field_id as 123 and field_value as "Public"; + records in which field_id
123 doesn't exist under attributes.
I tried
var condition = { "attributes" : {$elemMatch:{field_id:"123",field_value:{ $in:["Public"] }}}};
queryObj.push(condition);
this works fine to fetch records having field_id as 123 and field_value as Public
But I also want to get records in which field_id as 123 doesn't exists, I tried this
var condition1 =
{ "attributes" : {$elemMatch:{field_id:"123",$exists:false}}}
queryObj.push(condition1);
but it returns an error as it's not right syntax.
Please guide how do I fetch as desired.
This is the expected output, As these records have only Public Value for 123 field_id or field_id as 123 DOES NOT EXIST in these.
[
{
"name" : "test",
"gender" : "male",
"attributes" : [
{
"field_id" : "123",
"field_value" : "['Public']"
},
{
"field_id" : "124",
"field_value" : "true"
},
{
"field_id" : "125",
"field_value" : "['Single']"
},
]
},
{
"name" : "test3",
"gender" : "male",
"attributes" : [
{
"field_id" : "123",
"field_value" : "['Public']"
},
{
"field_id" : "125",
"field_value" : "['Married']"
},
]
},
{
"name" : "test2",
"gender" : "male",
"attributes" : [
{
"field_id" : "125",
"field_value" : "['Married']"
},
]
},
{
"name" : "test4",
"gender" : "male",
"attributes" : [
]
}
]

Answer 1

you should use two $elemMatch with $or operator.
your query should be something like this.
db.collection.find({
$or: [
{
"attributes": {
"$elemMatch": {
field_id: "123",
field_value: "['Public']"
}
}
},
{
"attributes": {
"$not": {
"$elemMatch": {
field_id: "123"
}
}
}
}
]
})
working example: https://mongoplayground.net/p/CP3HSKmNpKM