Iterate a cursor and print a document in MongoDB?

To iterate a cursor and print documents in MongoDB, use the forEach() method with printjson. This approach allows you to process each document individually and format the output for better readability.

Syntax

db.collection.find().forEach(printjson);

Create Sample Data

Let's create a collection with student documents ?

db.cursorDemo.insertMany([
    {"StudentFullName": "John Smith", "StudentAge": 23},
    {"StudentFullName": "John Doe", "StudentAge": 21},
    {"StudentFullName": "Carol Taylor", "StudentAge": 20},
    {"StudentFullName": "Chris Brown", "StudentAge": 24}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5cc7f0d08f9e6ff3eb0ce442"),
        ObjectId("5cc7f0df8f9e6ff3eb0ce443"),
        ObjectId("5cc7f0eb8f9e6ff3eb0ce444"),
        ObjectId("5cc7f0f88f9e6ff3eb0ce445")
    ]
}

Method 1: Using forEach() with printjson

Iterate through all documents and print them using printjson ?

db.cursorDemo.find().forEach(printjson);

{
    "_id": ObjectId("5cc7f0d08f9e6ff3eb0ce442"),
    "StudentFullName": "John Smith",
    "StudentAge": 23
}
{
    "_id": ObjectId("5cc7f0df8f9e6ff3eb0ce443"),
    "StudentFullName": "John Doe",
    "StudentAge": 21
}
{
    "_id": ObjectId("5cc7f0eb8f9e6ff3eb0ce444"),
    "StudentFullName": "Carol Taylor",
    "StudentAge": 20
}
{
    "_id": ObjectId("5cc7f0f88f9e6ff3eb0ce445"),
    "StudentFullName": "Chris Brown",
    "StudentAge": 24
}

Method 2: Using Projection with forEach()

Display only specific fields like "StudentFullName" and "StudentAge" (excluding _id) ?

db.cursorDemo.find({}, {"StudentFullName": 1, "StudentAge": 1, "_id": 0}).forEach(printjson);

{"StudentFullName": "John Smith", "StudentAge": 23}
{"StudentFullName": "John Doe", "StudentAge": 21}
{"StudentFullName": "Carol Taylor", "StudentAge": 20}
{"StudentFullName": "Chris Brown", "StudentAge": 24}

Key Points

• forEach(printjson) processes each document individually with proper JSON formatting.
• Use projection ({"field": 1, "_id": 0}) to display only specific fields.
• printjson automatically formats the output for better readability.

Conclusion

The forEach(printjson) method provides an efficient way to iterate through MongoDB cursors and print formatted documents. Combine it with projection to display only the required fields.