RealmProperty cannot decode null values

[miklselsoe]

After RealmOptional was deprecated, I changed all my RealmOptional<Type> properties to RealmProperty<Type?>

I have a few places where I relied on RealmOptional being Codable. With RealmProperty also being Codable, I thought it was safe to change the property definitions. Unfortunately, while RealmOptional was able to decode null values, RealmProperty cannot:

Swift.DecodingError.valueNotFound(Swift.Optional<Swift.Double>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "fromKm", intValue: nil)], debugDescription: "Expected Optional<Double> but found null value instead.", underlyingError: nil))

Looking at the implementation for the two types, it is evident that RealmProperty ignores null values, while RealmOptional does not:

extension RealmProperty: Codable where Value: Codable {
    public convenience init(from decoder: Decoder) throws {
        self.init()
        // `try decoder.singleValueContainer().decode(Value?.self)` incorrectly
        // rejects null values: https://bugs.swift.org/browse/SR-7404
        let container = try decoder.singleValueContainer()
        self.value = try container.decode(Value.self)
    }

    public func encode(to encoder: Encoder) throws {
        try self.value.encode(to: encoder)
    }
}https://github.com/realm/realm-cocoa/blob/v10.9.0/RealmSwift/RealmProperty.swift#L70-L76

extension RealmOptional: Codable where Value: Codable {
    public convenience init(from decoder: Decoder) throws {
        self.init()
        // `try decoder.singleValueContainer().decode(Value?.self)` incorrectly
        // rejects null values: https://bugs.swift.org/browse/SR-7404
        let container = try decoder.singleValueContainer()
        self.value = container.decodeNil() ? nil : try container.decode(Value.self)
    }

    public func encode(to encoder: Encoder) throws {
        try self.value.encode(to: encoder)
    }
}https://github.com/realm/realm-cocoa/blob/v10.9.0/RealmSwift/Optional.swift#L78-L84

I think this is a bug. I wonder if there is a better workaround than reverting to RealmOptional?

Version of Realm and Tooling

Realm framework version: 10.8.0

Xcode version: 12.5.1

iOS/OSX version: 14.6

Dependency manager + version: Carthage 0.38.0

[leemaguire]

Hi @miklselsoe

I will look into this for you.

[miklselsoe]

Are these two issues related?
#7332

[leemaguire]

Hi @miklselsoe The problems are not interdependant on one another.