Database

[{ "my_id": { "Product": "Pork Soup", "Protein": 100.0 } }, { "my_id": { "Product": "Duck Sandwich", "Protein": 1000.1 } }, { "my_id": { "Product": "Chicken Roll", "Protein": 100.69 } }, { "my_id": { "Product": "Disgusting Tofu", "Protein": 0.1 } }, { "my_id": { "Product": "Cardboard Casserole", "Protein": 50.0 } }]

Query

db.collection.aggregate([{ "$project": { "w": { "$split": ["$my_id.Product", " "] }, "Product": "$my_id.Product", "Protein": "$my_id.Protein" } }, { "$project": { "_id": 0, "Product": 1, "Protein": 1, "Category": { "$switch": { "branches": [{ "case": { "$in": ["Pork", "$w"] }, "then": "Pork" }, { "case": { "$in": ["Chicken", "$w"] }, "then": "Chicken" }, { "case": { "$in": ["Tofu", "$w"] }, "then": "Tofu" } ], "default": "NA" } } } } ])

Result