How to query all items in MongoDB?

To query all items in a MongoDB collection, use the find() method. This method retrieves all documents from a collection when called without parameters, or you can specify query criteria and projection options to filter results.

Syntax

db.collection.find()
db.collection.find(query, projection)

Create Sample Data

Let us first create a collection with documents ?

db.queryAllItemsDemo.insertMany([
    {
        "StudentDetails": {
            "StudentName": "John",
            "StudentSubject": ["MongoDB", "MySQL"],
            "StudentSubjectPrice": [4000, 6000]
        },
        "OtherDetails": {
            "UserAge": 29,
            "UserCountryName": "US"
        }
    },
    {
        "StudentDetails": {
            "StudentName": "Alice",
            "StudentSubject": ["Python", "Java"],
            "StudentSubjectPrice": [3500, 5500]
        },
        "OtherDetails": {
            "UserAge": 25,
            "UserCountryName": "Canada"
        }
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cef74ecef71edecf6a1f69f"),
        ObjectId("5cef74ecef71edecf6a1f6a0")
    ]
}

Method 1: Query All Documents

Display all documents from a collection with the help of find() method ?

db.queryAllItemsDemo.find().pretty();

{
    "_id": ObjectId("5cef74ecef71edecf6a1f69f"),
    "StudentDetails": {
        "StudentName": "John",
        "StudentSubject": [
            "MongoDB",
            "MySQL"
        ],
        "StudentSubjectPrice": [
            4000,
            6000
        ]
    },
    "OtherDetails": {
        "UserAge": 29,
        "UserCountryName": "US"
    }
}
{
    "_id": ObjectId("5cef74ecef71edecf6a1f6a0"),
    "StudentDetails": {
        "StudentName": "Alice",
        "StudentSubject": [
            "Python",
            "Java"
        ],
        "StudentSubjectPrice": [
            3500,
            5500
        ]
    },
    "OtherDetails": {
        "UserAge": 25,
        "UserCountryName": "Canada"
    }
}

Method 2: Query with Projection

Query all items but display only specific fields using projection ?

db.queryAllItemsDemo.find({}, {StudentDetails: 1}).pretty();

{
    "_id": ObjectId("5cef74ecef71edecf6a1f69f"),
    "StudentDetails": {
        "StudentName": "John",
        "StudentSubject": [
            "MongoDB",
            "MySQL"
        ],
        "StudentSubjectPrice": [
            4000,
            6000
        ]
    }
}
{
    "_id": ObjectId("5cef74ecef71edecf6a1f6a0"),
    "StudentDetails": {
        "StudentName": "Alice",
        "StudentSubject": [
            "Python",
            "Java"
        ],
        "StudentSubjectPrice": [
            3500,
            5500
        ]
    }
}

Conclusion

The find() method is the primary way to query all items in MongoDB. Use it without parameters to get all documents, or add projection to control which fields are returned in the results.