How to aggregate distinct array field in mongodb?

@muriel.schmidt 

To aggregate distinct array field in MongoDB, you can use the $unwind and $group operators. Here's an example of how you can achieve this:

Suppose you have a collection called orders, and each document in this collection has an array field called products. To aggregate distinct products in this array field, you can use the following aggregation pipeline:

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db.orders.aggregate([
  { $unwind: "$products" },
  { $group: {
    _id: "$products",
    count: { $sum: 1 }
  }}
])

In this aggregation pipeline:

1. The $unwind operator is used to deconstruct the products array field, which creates a separate document for each element in the array.
2. The $group operator is then used to group the documents by the products field and calculate the count of each distinct product.

This will give you a result with distinct products in the products array field along with their respective counts.