北京顺义黑马前端就业133期

db.inventory2.aggregate( [ { $unwind: "$sizes" } ] ) db.inventory2.aggregate( [ { $unwind: { path: "$sizes" } } ] )

结果

{ "_id" : 1, "item" : "ABC", "price" : NumberDecimal("80"), "sizes" : "S" }{ "_id" : 1, "item" : "ABC", "price" : NumberDecimal("80"), "sizes" : "M" }{ "_id" : 1, "item" : "ABC", "price" : NumberDecimal("80"), "sizes" : "L" }{ "_id" : 3, "item" : "IJK", "price" : NumberDecimal("160"), "sizes" : "M" }