Retrieving array values from a find query in MongoDB database

To retrieve array values from a find query in MongoDB, use dot notation to access nested fields within array elements. This allows you to query specific properties of objects stored in arrays.

Syntax

db.collection.find({"arrayName.fieldName": "value"});

Sample Data

Let us create a collection with documents containing arrays of client details ?

db.demo38.insertMany([
    {"ClientDetails": [{"ClientId": 101, "ClientName": "Chris"}]},
    {"ClientDetails": [{"ClientId": 102, "ClientName": "David"}]},
    {"ClientDetails": [{"ClientId": 103, "ClientName": "Mike"}]}
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e176abccfb11e5c34d898d9"),
        ObjectId("5e176ac7cfb11e5c34d898da"),
        ObjectId("5e176ad0cfb11e5c34d898db")
    ]
}

Display all documents from the collection ?

db.demo38.find();

{ "_id": ObjectId("5e176abccfb11e5c34d898d9"), "ClientDetails": [{"ClientId": 101, "ClientName": "Chris"}] }
{ "_id": ObjectId("5e176ac7cfb11e5c34d898da"), "ClientDetails": [{"ClientId": 102, "ClientName": "David"}] }
{ "_id": ObjectId("5e176ad0cfb11e5c34d898db"), "ClientDetails": [{"ClientId": 103, "ClientName": "Mike"}] }

Example: Query Array Values Using Dot Notation

Following is the query to retrieve documents where the ClientName is "David" ?

db.demo38.find({"ClientDetails.ClientName": "David"});

{ "_id": ObjectId("5e176ac7cfb11e5c34d898da"), "ClientDetails": [{"ClientId": 102, "ClientName": "David"}] }

Key Points

• Use arrayName.fieldName syntax to query nested fields within arrays
• MongoDB automatically searches all elements in the array for the specified condition
• The query returns the entire document when a match is found

Conclusion

Dot notation provides a simple way to query array elements in MongoDB. Use arrayName.fieldName to search for specific values within nested objects in arrays.