How to exclude _id without including other fields using the aggregation framework in MongoDB?

To exclude the _id field without explicitly including other fields in MongoDB's aggregation framework, use the $project stage with _id: 0 and selectively include only the fields you need.

Syntax

db.collection.aggregate([
    {
        $project: {
            _id: 0,
            "field1": 1,
            "field2": 1
        }
    }
]);

Sample Data

db.excludeIdDemo.insertMany([
    {"StudentFirstName": "John", "StudentAge": 21},
    {"StudentFirstName": "Robert", "StudentAge": 20},
    {"StudentFirstName": "Chris", "StudentAge": 24}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cd701a56d78f205348bc632"),
        ObjectId("5cd701af6d78f205348bc633"),
        ObjectId("5cd701b86d78f205348bc634")
    ]
}

Display All Documents

db.excludeIdDemo.find();

{ "_id" : ObjectId("5cd701a56d78f205348bc632"), "StudentFirstName" : "John", "StudentAge" : 21 }
{ "_id" : ObjectId("5cd701af6d78f205348bc633"), "StudentFirstName" : "Robert", "StudentAge" : 20 }
{ "_id" : ObjectId("5cd701b86d78f205348bc634"), "StudentFirstName" : "Chris", "StudentAge" : 24 }

Example: Exclude _id and Include Specific Fields

To exclude _id and show only StudentFirstName ?

db.excludeIdDemo.aggregate([
    {
        $project: {
            _id: 0,
            "StudentFirstName": 1
        }
    }
]);

{ "StudentFirstName" : "John" }
{ "StudentFirstName" : "Robert" }
{ "StudentFirstName" : "Chris" }

Key Points

• Set _id: 0 to exclude the _id field from the output.
• Use fieldName: 1 to explicitly include specific fields.
• In $project, you must either include fields (1) or exclude them (0), but not mix both except for _id.

Conclusion

The $project stage with _id: 0 effectively excludes the _id field while allowing selective inclusion of other fields. This approach gives you precise control over the output structure in aggregation pipelines.