Get specific elements from embedded array in MongoDB?

To get specific elements from an embedded array in MongoDB, use the $unwind operator to deconstruct the array, then $match with dot notation to filter elements based on specific criteria.

Syntax

db.collection.aggregate([
    { $unwind: "$arrayField" },
    { $match: { "arrayField.fieldName": value } },
    { $project: { _id: 0, arrayField: 1 } }
]);

Sample Data

db.demo641.insertOne({
    ProductId: 101,
    "ProductInformation": [
        {
            ProductName: "Product-1",
            "ProductPrice": 1000
        },
        {
            ProductName: "Product-2",
            "ProductPrice": 500
        },
        {
            ProductName: "Product-3",
            "ProductPrice": 2000
        },
        {
            ProductName: "Product-4",
            "ProductPrice": 3000
        }
    ]
});

{ "acknowledged" : true, "insertedId" : ObjectId("...") }

Display all documents from the collection ?

db.demo641.find();

{
    "_id" : ObjectId("5e9c31d46c954c74be91e6e2"), 
    "ProductId" : 101, 
    "ProductInformation" : [
        { "ProductName" : "Product-1", "ProductPrice" : 1000 },
        { "ProductName" : "Product-2", "ProductPrice" : 500 },
        { "ProductName" : "Product-3", "ProductPrice" : 2000 },
        { "ProductName" : "Product-4", "ProductPrice" : 3000 }
    ]
}

Example: Get Products with Specific Prices

Get products with prices 1000 or 2000 ?

db.demo641.aggregate([
    { $unwind: "$ProductInformation" },
    { $match: { "ProductInformation.ProductPrice": { $in: [1000, 2000] } } },
    { $project: { _id: 0, ProductInformation: 1 } }
]);

{
    "ProductInformation" : {
        "ProductName" : "Product-1",
        "ProductPrice" : 1000
    }
}
{
    "ProductInformation" : {
        "ProductName" : "Product-3",
        "ProductPrice" : 2000
    }
}

How It Works

• $unwind creates a separate document for each array element
• $match filters documents based on embedded field values
• $project shapes the output to show only required fields

Conclusion

Use $unwind followed by $match in an aggregation pipeline to extract specific elements from embedded arrays. This approach allows precise filtering based on nested field values.