$unwind deconstructs an array field from the input documents to output a document for each element. $facet processes multiple aggregation pipelines within a single stage on the same set of input documents.
MongoDB $unwind and $facet
Deconstruct array fields and execute multiple aggregation stages concurrently.
Key Takeaways: MongoDB $unwind and $facet
Mastering MongoDB $unwind and $facet helps you write clean and reliable MongoDB code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.
MongoDB $unwind and $facet Code Example
MongoDBdb.inventory.aggregate([
{ $unwind: "$tags" },
{ $group: { _id: "$tags", count: { $sum: 1 } } }
]);Output
Outputs tag frequency counts across inventory items
Run this example on your own computer. The "Get Started" lesson shows how to set it up.
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