mongoDB with API sample

https://dzone.com/articles/three-approaches-to-creating-a-sql-join-equivalent

Exaple of Join https://docs.mongodb.com/manual/reference/operator/aggregation/lookup/

db.orders.insert([ { "_id" : 1, "item" : "almonds", "price" : 12, "quantity" : 2 }, { "_id" : 2, "item" : "pecans", "price" : 20, "quantity" : 1 }, { "_id" : 3 } ])

db.inventory.insert([ { "_id" : 1, "sku" : "almonds", description: "product 1", "instock" : 120 }, { "_id" : 2, "sku" : "bread", description: "product 2", "instock" : 80 }, { "_id" : 3, "sku" : "cashews", description: "product 3", "instock" : 60 }, { "_id" : 4, "sku" : "pecans", description: "product 4", "instock" : 70 }, { "_id" : 5, "sku": null, description: "Incomplete" }, { "_id" : 6 } ])

db.orders.aggregate([ { $lookup: { from: "inventory", localField: "item", foreignField: "sku", as: "inventory_docs" } } ])

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db.orders.insert([ { "_id" : 10, "item" : "MON1003", "price" : 350, "quantity" : 2, "specs" : [ "27 inch", "Retina display", "1920x1080" ], "type" : "Monitor" } ])

db.inventory.insert([ { "_id" : 10, "sku" : "MON1003", "type" : "Monitor", "instock" : 120, "size" : "27 inch", "resolution" : "1920x1080" } ])

db.orders.aggregate([ { $unwind: "$specs" }, { $lookup: { from: "inventory", localField: "specs", foreignField: "size", as: "inventory_docs" } }, { $match: { "inventory_docs": { $ne: [] } } } ])