Mongodb circuit design

Question

I am confused, the best format for the following case:

Name: Pretty nice hot dog
Stock: 10
Weight: 0.1 grams
Price: 2 dollars

Name: An ordinary dumbbell
Stock: 5
Weight: 4 kilograms
Price: 667.98 yens

It:

db.item.save ({"_id" : 1, "name" : "Pretty nice hot dog", "stock" : 10, "weight" : {"value" : 0.1, "unit" : "gram"}, "price" : {"value" : 2, "unit" : "dollar"}})
db.item.save ({"_id" : 2, "name" : "An ordinary dumbbell", "stock" : 5, "weight" : {"value" : 4, "unit" : "kilogram"}, "price" : {"value" : 667.98, "unit" : "yen"}})

Or that:

db.unit.save ({"_id" : 1, "name" : "dollar"})
db.unit.save ({"_id" : 2, "name" : "yen"})
db.unit.save ({"_id" : 4, "name" : "gram"})
db.unit.save ({"_id" : 5, "name" : "kilogram"})

db.item.save ({"_id" : 1, "name" : "Pretty nice hot dog", "stock" : 10, "weight" : {"value" : 0.1, "unit" : [new DBRef ("unit", 4)]}, "price" : [new DBRef ("unit", 1)]})
db.item.save ({"_id" : 2, "name" : "An ordinary dumbbell", "stock" : 5, "weight" : {"value" : 4, "unit" : [new DBRef ("unit", 5)]}, "price" : [new DBRef ("unit", 2)]})

The values ​​of the "unit" field are immutable, I do not know whether to put it in a separate collection.

thank

Answer 1

I would say no. If you do not need flexibility in the request for units (all items with a certain cost), I would not do that. And if you need to, you can always use card reduction to later receive all items of a certain value.

Answer 2

Read the Design Diagram from MongoDb docs. This is your case.