✅ Node.js MongoDB Join (Using $lookup)

MongoDB does not support SQL-style joins, but it has a powerful aggregation operator called $lookup that allows joining two collections.

⭐ Example Collections

customers collection:

orders collection:

We will join customers and orders using:

⭐ 1. Basic Join Example

⭐ Output Example

⭐ 2. Join + Match (LIKE WHERE + JOIN)

Get only customers from Surat with their orders:

⭐ 3. Join + Unwind (Flatten array)

$unwind converts the joined array into individual documents.

⭐ 4. Join With Projection (Select Specific Fields)

⭐ 5. Multiple Joins

You can join more than 2 collections:

⭐ 6. Full Working Example (Node.js)