Virtual

@propertyWrapper
public struct Virtual<V> : AttributeKeyPathStringConvertible, FieldAttributeProtocol

The containing type for computed property values. Because this value is not persisted to the backing store, any type is supported. Field.Virtual properties are not allowed to have initial values, including nil for optional types.

class Animal: CoreStoreObject {

    @Field.Virtual(
        "pluralName",
        customGetter: { (object, field) in
            return object.$species.value + "s"
        }
    )
    var pluralName: String

    @Field.Stored("species")
    var species: String = ""
}

Important

Field properties are required to be used as @propertyWrappers. Any other declaration not using the @Field.Virtual(...) var syntax will be ignored.

  • Initializes the metadata for the property. Field.Virtual properties are not allowed to have initial values, including nil for optional types.

    class Person: CoreStoreObject {

    @Field.Virtual(
        "pluralName",
        customGetter: { (object, field) in
            return object.$species.value + "s"
        }
    )
    var pluralName: String

    @Field.Stored("species")
    var species: String = ""
}

    Declaration

    Swift

    public init(
    _ keyPath: KeyPathString,
    customGetter: @escaping (_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>) -> V,
    customSetter: ((_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>, _ newValue: V) -> Void)? = nil,
    affectedByKeyPaths: @autoclosure @escaping () -> Set<KeyPathString> = [])

    Parameters

    keyPath

    the permanent attribute name for this property.
    customGetter

    use this closure as an “override” for the default property getter. The closure receives a ObjectProxy<O>, which acts as a type-safe proxy for the receiver. When accessing the property value from ObjectProxy<O>, make sure to use field.primitiveValue instead of field.value, which would unintentionally execute the same closure again recursively. Do not make assumptions on the thread/queue that the closure is executed on; accessors may be called from NSError logs for example.
    customSetter

    use this closure as an “override” for the default property setter. The closure receives a ObjectProxy<O>, which acts as a fast, type-safe KVC interface for CoreStoreObject. The reason a CoreStoreObject instance is not passed directly is because the Core Data runtime is not aware of CoreStoreObject properties’ static typing, and so loading those info everytime KVO invokes this accessor method incurs a cumulative performance hit (especially in KVO-heavy operations such as ListMonitor observing.) When accessing the property value from ObjectProxy<O>, make sure to use field.primitiveValue instead of field.value, which would unintentionally execute the same closure again recursively.
    affectedByKeyPaths

    a set of key paths for properties whose values affect the value of the receiver. This is similar to NSManagedObject.keyPathsForValuesAffectingValue(forKey:).

AnyKeyPathStringConvertible

  • Declaration

    Swift

    public var cs_keyPathString: String { get }

KeyPathStringConvertible

AttributeKeyPathStringConvertible

Available where V: FieldOptionalType

  • Initializes the metadata for the property. Field.Virtual properties are not allowed to have initial values, including nil for optional types.

    class Person: CoreStoreObject {

    @Field.Virtual(
        "pluralName",
        customGetter: { (object, field) in
            return object.$species.value + "s"
        }
    )
    var pluralName: String?

    @Field.Stored("species")
    var species: String = ""
}

    Declaration

    Swift

    public init(
    _ keyPath: KeyPathString,
    customGetter: ((_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>) -> V)? = nil,
    customSetter: ((_ object: ObjectProxy<O>, _ field: ObjectProxy<O>.FieldProxy<V>, _ newValue: V) -> Void)? = nil,
    affectedByKeyPaths: @autoclosure @escaping () -> Set<KeyPathString> = [])

    Parameters

    keyPath

    the permanent attribute name for this property.
    customGetter

    use this closure as an “override” for the default property getter. The closure receives a ObjectProxy<O>, which acts as a type-safe proxy for the receiver. When accessing the property value from ObjectProxy<O>, make sure to use field.primitiveValue instead of field.value, which would unintentionally execute the same closure again recursively. Do not make assumptions on the thread/queue that the closure is executed on; accessors may be called from NSError logs for example.
    customSetter

    use this closure as an “override” for the default property setter. The closure receives a ObjectProxy<O>, which acts as a fast, type-safe KVC interface for CoreStoreObject. The reason a CoreStoreObject instance is not passed directly is because the Core Data runtime is not aware of CoreStoreObject properties’ static typing, and so loading those info everytime KVO invokes this accessor method incurs a cumulative performance hit (especially in KVO-heavy operations such as ListMonitor observing.) When accessing the property value from ObjectProxy<O>, make sure to use field.primitiveValue instead of field.value, which would unintentionally execute the same closure again recursively.
    affectedByKeyPaths

    a set of key paths for properties whose values affect the value of the receiver. This is similar to NSManagedObject.keyPathsForValuesAffectingValue(forKey:).