CODEWITHSUNDEEP
iosswiftrealm
H4Hugo
H4Hugo

Reputation: 2650

How to set Realm primaryKey on a class "sub-property"

Say I have a class and its Realm representation that looks like this: 

class Dog {
    var identifier: String
    var age: Int
    ...

    override static func primaryKey() -> String? {
        return "identifier"
    }
}

Now here is what my new Identifier class looks like:

class Identifier {
    var functionalId: String
    var version: String
    ...
}

I need to replace my Dog's identifier String property to be an Identifier like this:

class Dog {
    var identifier: Identifier
    var age: Int
    ...

    override static func primaryKey() -> String? {
        return "identifier" // I need to change this
    }
}

but I'm having a hard time replacing the content of the primaryKey() method:

How do I tell Realm to look for an object's sub property for the primaryKey() ?

I tried something like:

override static func primaryKey() -> String? {
    return "identifier.functionalId"
}

But it seems that I was too naive, it won't work

** EDIT ** Following comments, here is the output of the crash I'm getting: 

Terminating app due to uncaught exception 'RLMException', reason: 'Primary key property 'identifier.functionalId' does not exist on object Dog

Sorry for bad English though, I couldn't find the words fir this simple problem, especially the title!

Upvotes: 2

Views: 398

Answers (2)

Kane Cheshire
Kane Cheshire

Reputation: 1712

How do I tell Realm to look for an object's sub property for the primaryKey()

You can't.

Looking at the errors you've mentioned:

If you try setting the primary key to:

override static func primaryKey() -> String? {
    return "identifier"
}

Then you get an error from Realm saying: Property 'identifier' cannot be made the primary key of 'Dog' because it is not a 'string' or 'int' property.

If you try setting the primary key to:

override static func primaryKey() -> String? {
    return "identifier.functionalId"
}

Then you get an error from Realm saying: Primary key property 'identifier.functionalId' does not exist on object Dog

This leads to the conclusion that the primary key must be of type String or Int, and it must be a property of Dog, not another class.

Upvotes: 0

davidethell
davidethell

Reputation: 12018

I've never tried this in Realm, but it might be possible using a dynamic variable for your primary key and a function that pulls the value from the sub-object:

var _identifier: Identifier

dynamic lazy var identifier: String = self.identifierValue()

override static func primaryKey() -> String? {
    return "identifier"
}

func identifierValue() -> String {
    return _identifier.functionalId
}

Upvotes: 1

Related Questions