Retrieving array values from a find query in MongoDB?

To retrieve array values from a MongoDB find query, use dot notation to access array fields and their nested properties. This allows you to query specific elements within arrays and filter documents based on array content.

Syntax

db.collection.find({"arrayField.nestedProperty": "value"});

Sample Data

db.retrievingArrayDemo.insertMany([
    {
        "UserDetails": [
            { "UserName": "John", "UserAge": 23 }
        ],
        "UserCountryName": "AUS",
        "UserLoginDate": new ISODate(),
        "UserMessage": "Hello"
    },
    {
        "UserDetails": [
            { "UserName": "Sam", "UserAge": 24 }
        ],
        "UserCountryName": "UK", 
        "UserLoginDate": new ISODate(),
        "UserMessage": "Bye"
    }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5ce9718478f00858fb12e920"),
        ObjectId("5ce9718478f00858fb12e921")
    ]
}

Example 1: Display All Documents

db.retrievingArrayDemo.find().pretty();

{
    "_id" : ObjectId("5ce9718478f00858fb12e920"),
    "UserDetails" : [
        {
            "UserName" : "John",
            "UserAge" : 23
        }
    ],
    "UserCountryName" : "AUS",
    "UserLoginDate" : ISODate("2019-05-25T16:47:00.211Z"),
    "UserMessage" : "Hello"
}
{
    "_id" : ObjectId("5ce9718478f00858fb12e921"),
    "UserDetails" : [
        {
            "UserName" : "Sam",
            "UserAge" : 24
        }
    ],
    "UserCountryName" : "UK",
    "UserLoginDate" : ISODate("2019-05-25T16:47:00.670Z"),
    "UserMessage" : "Bye"
}

Example 2: Query Array Values Using Dot Notation

Retrieve documents where UserCountryName is "UK" and UserDetails array contains a user named "Sam" :

db.retrievingArrayDemo.find({
    "UserCountryName": "UK",
    "UserDetails.UserName": "Sam"
}).pretty();

{
    "_id" : ObjectId("5ce9718478f00858fb12e921"),
    "UserDetails" : [
        {
            "UserName" : "Sam",
            "UserAge" : 24
        }
    ],
    "UserCountryName" : "UK",
    "UserLoginDate" : ISODate("2019-05-25T16:47:00.670Z"),
    "UserMessage" : "Bye"
}

Key Points

• Use dot notation (arrayField.property) to access nested properties within arrays
• MongoDB automatically searches through all array elements for matching values
• Multiple conditions can be combined to filter documents precisely

Conclusion

Dot notation provides a simple way to query array values in MongoDB. Use "arrayField.nestedProperty" syntax to filter documents based on array content and retrieve specific data efficiently.