Get attribute list from MongoDB object?

To get attribute list from MongoDB object, use a for...in loop to iterate through the document properties and extract each key and value along with their data types.

Syntax

var document = db.collection.findOne();
for (key in document) {
    var value = document[key];
    print(key + "(" + typeof(value) + "): " + value);
}

Create Sample Data

db.getAttributeListDemo.insertOne({
    "StudentId": 101,
    "StudentName": "John",
    "StudentAdmissionDate": new ISODate('2019-01-12'),
    "StudentSubjects": ["MongoDB", "Java", "MySQL"]
});

{
    "acknowledged": true,
    "insertedId": ObjectId("5cbdfcc9ac184d684e3fa269")
}

Display Document

db.getAttributeListDemo.find().pretty();

{
    "_id": ObjectId("5cbdfcc9ac184d684e3fa269"),
    "StudentId": 101,
    "StudentName": "John",
    "StudentAdmissionDate": ISODate("2019-01-12T00:00:00Z"),
    "StudentSubjects": [
        "MongoDB",
        "Java",
        "MySQL"
    ]
}

Extract Attribute List

var myDocument = db.getAttributeListDemo.findOne();
for (myKey in myDocument) {
    var originalValue = myDocument[myKey];
    print(myKey + "(" + typeof(originalValue) + "): " + originalValue);
}

_id(object): 5cbdfcc9ac184d684e3fa269
StudentId(number): 101
StudentName(string): John
StudentAdmissionDate(object): Sat Jan 12 2019 05:30:00 GMT+0530 (India Standard Time)
StudentSubjects(object): MongoDB,Java,MySQL

Key Points

• The for...in loop iterates through all enumerable properties of the document
• typeof() returns the JavaScript data type of each field value
• Arrays and dates appear as "object" type in the output

Conclusion

Use a for...in loop with findOne() to extract all document attributes, their data types, and values. This method provides a complete overview of the document structure and field types.