how to implement multiple user on realm database in iOS? - ios

Question

I am a beginner on programming and especially on iOS development
currently I am trying to use realm as the local database in an ecommerce app. I have Product and WishList object of Realm like below
The product:
class Product : Object {
#objc dynamic var productID : Int = 0
#objc dynamic var name : String = ""
#objc dynamic var categoryID : Int = 0
#objc dynamic var categoryName : String = ""
#objc dynamic var unitPrice: Double = 0.0
#objc dynamic var quantityInCart = 0
#objc dynamic var quantityFromServer = 0
#objc dynamic var descriptionProduct : String = ""
#objc dynamic var hasBeenAddedToWishList : Bool = false
#objc dynamic var hasBeenAddedToCart : Bool = false
#objc dynamic var isNewProduct : Bool = false
#objc dynamic var productWeight : String = ""
#objc dynamic var weightUnit : String = ""
#objc dynamic var minimumOrderQuantity = 0
#objc dynamic var maximumOrderQuantity = 0
override static func primaryKey() -> String? {
return "productID"
}
}
the Wishlist:
class WishList : Object {
var products = List<Product>()
}
my app can change the user. so let say if User A put some products on the wishlist (populates the WishList object with the product), after that he performs Log Out,
then it will make the User B's wishlist object will already have object after User B login.
so I think I need to insert userID both on Product and Wishlist object, and I have to also remove the primary key on Product object.
override static func primaryKey() -> String? {
return "productID"
}
so when I perform query or filter from realm database I can filter based on productID and also userID.
do I have the correct approach using way like that ? or is there a better approach? because to I am not comfortable having userID as the property of Product object like code below:
class Product : Object {
#objc dynamic var userID : Int = 0 <--- like this
#objc dynamic var productID : Int = 0
#objc dynamic var name : String = ""
#objc dynamic var categoryID : Int = 0
#objc dynamic var categoryName : String = ""
#objc dynamic var unitPrice: Double = 0.0
#objc dynamic var quantityInCart = 0
#objc dynamic var quantityFromServer = 0
#objc dynamic var descriptionProduct : String = ""
}
class WishList : Object {
#objc dynamic var userID : Int = 0 <--- and like this
var products = List<Product>()
}
and with this approach, I will also have 'duplicate' Product data on Product object with the same productID, but the userID on the property of the Product is different

Answer 1

You shouldn't add userID to either the Product or the Wishlist. A Product should be independent of specific users, so it should have no relationship to a user. On the other hand, a Wishlist is specific to a user, but instead of manually having to query the userID property of a specific Wishlist, you should take advantage of Realm's built-in relationships and declare a one-to-one relationship between a User and a Wishlist (you can either declare the relationship on WishList or on User, both work just fine).
So your Product definition should be left unchanged with its primaryKey being intact as well. Your Wishlist should look like the following:
class WishList : Object {
#objc dynamic var user: User?
let products = List<Product>()
}
Or if you want to access the WishList of a specific User from the user, you can modify your User like so:
class User: Object {
#objc dynamic var wishList: WishList?
...
}