Drop CodableBox, not required?

Directly store the Codable Swift value in the
property as an Any.

Disadvantage: We cannot set the `transformedValueClass`
in the transformer nor the `attributeValueClassName` in
the `Attribute` (which will stick to `Any`.
But that doesn't seem to confused CoreData.

Sources/ManagedModels/PersistentModel/PersistentModel+KVC.swift

@@ -232,14 +232,14 @@ public extension PersistentModel {
 
   func setValue<T>(forKey key: String, to value: T) where T: Codable {
     willChangeValue(forKey: key); defer { didChangeValue(forKey: key) }
-    setPrimitiveValue(CodableBox<T>(value), forKey: key)
+    setPrimitiveValue(value, forKey: key)
   }
 
   func setValue<T>(forKey key: String, to value: T)
          where T: Codable & AnyOptional
   {
     willChangeValue(forKey: key); defer { didChangeValue(forKey: key) }
-    if value.isSome { setPrimitiveValue(CodableBox<T>(value), forKey: key) }
+    if value.isSome { setPrimitiveValue(value, forKey: key) }
     else { setPrimitiveValue(nil, forKey: key) }
   }
 
@@ -249,10 +249,7 @@ public extension PersistentModel {
       fatalError("No box found for non-optional Codable value for key \(key)?")
     }
 
-    if let box = value as? CodableBox<T> {
-      guard let value = box.value else {
-        fatalError("Box has no value for non-optional Codable for key \(key)?")
-      }
+    if let value = value as? T {
       return value
     }
 
@@ -266,17 +263,13 @@ public extension PersistentModel {
       }
     }
 
-    guard let value = value as? T else {
-      fatalError("Unexpected value for key \(key)? \(value)")
-    }
-    assertionFailure("Codable value is directly stored? \(value)")
-    return value
+    fatalError("Codable value type doesn't match? \(value)")
   }
 
   func getValue<T>(forKey key: String) -> T where T: Codable & AnyOptional {
     willAccessValue(forKey: key); defer { didAccessValue(forKey: key) }
     guard let value = primitiveValue(forKey: key) else { return .noneValue }
-    if let box = value as? CodableBox<T> { return box.value ?? .noneValue }
+    if let value = value as? T { return value }
 
     if let data = value as? Data {
       assertionFailure("Unexpected Data as primitive!")
@@ -291,7 +284,7 @@ public extension PersistentModel {
     guard let value = value as? T else {
       fatalError("Unexpected value for key \(key)? \(value)")
     }
-    assertionFailure("Codable value is directly stored? \(value)")
-    return value
+    assertionFailure("Codable value type doesn't match? \(value)")
+    return .noneValue
   }
 }

Sources/ManagedModels/SchemaCompatibility/CodableTransformer.swift

@@ -0,0 +1,48 @@
+//
+//  Created by Helge Heß.
+//  Copyright © 2023 ZeeZide GmbH.
+//
+
+import Foundation
+import CoreData
+
+final class CodableTransformer<T: Codable>: ValueTransformer {
+
+  #if false
+  override class func transformedValueClass() -> AnyClass {
+    T.self // doesn't work
+  }
+  #endif
+  override class func allowsReverseTransformation() -> Bool { true }
+
+  override func transformedValue(_ value: Any?) -> Any? {
+    // value is the box
+    guard let value else { return nil }
+    guard let typed = value as? T else {
+      assertionFailure("Value to be transformed is not the right type? \(value)")
+      return nil
+    }
+    do {
+      return try JSONEncoder().encode(typed)
+    }
+    catch {
+      assertionFailure("Could not encode JSON value of property? \(error)")
+      return nil
+    }
+  }
+
+  override func reverseTransformedValue(_ value: Any?) -> Any? {
+    guard let value else { return nil }
+    guard let data = value as? Data else {
+      assert(value is Data, "Reverse value is not `Data`?")
+      return nil
+    }
+    do {
+      return try JSONDecoder().decode(T.self, from: data)
+    }
+    catch {
+      assertionFailure("Could not decode JSON value of property? \(error)")
+      return nil
+    }
+  }
+}

Sources/ManagedModels/SchemaCompatibility/NSAttributeDescription+Data.swift

@@ -40,8 +40,8 @@ extension CoreData.NSAttributeDescription: SchemaProperty {
 
       if let primitiveType = newValue as? CoreDataPrimitiveValue.Type {
         let config = primitiveType.coreDataValue
-        self.attributeType           = config.attributeType
-        self.isOptional              = config.isOptional
+        self.attributeType = config.attributeType
+        self.isOptional    = config.isOptional
         if let newClassName = config.attributeValueClassName {
           self.attributeValueClassName = newClassName
         }
@@ -55,8 +55,8 @@ extension CoreData.NSAttributeDescription: SchemaProperty {
           let rawType = type.RawValue.self
           if let primitiveType = rawType as? CoreDataPrimitiveValue.Type {
             let config = primitiveType.coreDataValue
-            self.attributeType           = config.attributeType
-            self.isOptional              = config.isOptional
+            self.attributeType = config.attributeType
+            self.isOptional    = config.isOptional
             if let newClassName = config.attributeValueClassName {
               self.attributeValueClassName = newClassName
             }
@@ -75,12 +75,14 @@ extension CoreData.NSAttributeDescription: SchemaProperty {
         self.isOptional    = newValue is any AnyOptional.Type
 
         func setValueClassName<T: Codable>(for type: T.Type) {
-          self.attributeValueClassName = NSStringFromClass(CodableBox<T>.self)
+          #if false // doesn't work
+          self.attributeValueClassName = NSStringFromClass(T.self)
+          #endif
 
-          let name = NSStringFromClass(CodableBox<T>.Transformer.self)
+          let name = NSStringFromClass(CodableTransformer<T>.self)
           if !ValueTransformer.valueTransformerNames().contains(.init(name)) {
             // no access to valueTransformerForName?
-            let transformer = CodableBox<T>.Transformer()
+            let transformer = CodableTransformer<T>()
             ValueTransformer
               .setValueTransformer(transformer, forName: .init(name))
           }

Tests/ManagedModelTests/CodablePropertiesTest.swift

@@ -32,15 +32,15 @@ final class CodablePropertiesTests: XCTestCase {
 
     let transformerName = try XCTUnwrap(
       ValueTransformer.valueTransformerNames().first(where: {
-        $0.rawValue.range(of: "CodableBox11TransformerVOO17ManagedModelTests8")
+        $0.rawValue.range(of: "CodableTransformerVOO17ManagedModelTests8")
         != nil
       })
     )
     let transformer = try XCTUnwrap(ValueTransformer(forName: transformerName))
     _ = transformer // to clear unused-wraning
 
-    XCTAssertTrue(attribute.valueType ==
-                  CodableBox<Fixtures.CodablePropertiesSchema.AccessSIP>.self)
+    XCTAssertTrue(attribute.valueType == Any.self)
+                  // Fixtures.CodablePropertiesSchema.AccessSIP.self
     XCTAssertNotNil(attribute.valueTransformerName)
     XCTAssertEqual(attribute.valueTransformerName, transformerName.rawValue)
   }
@@ -54,7 +54,7 @@ final class CodablePropertiesTests: XCTestCase {
     // CodableBox.
     let transformerName = try XCTUnwrap(
       ValueTransformer.valueTransformerNames().first(where: {
-        $0.rawValue.range(of: "CodableBox11TransformerVOO17ManagedModelTests8")
+        $0.rawValue.range(of: "CodableTransformerVOO17ManagedModelTests8")
         != nil
       })
     )
@@ -63,8 +63,8 @@ final class CodablePropertiesTests: XCTestCase {
 
     let attribute = try XCTUnwrap(entity.attributesByName["sip"])
     XCTAssertEqual(attribute.name, "sip")
-    XCTAssertTrue(attribute.valueType == 
-                  CodableBox<Fixtures.CodablePropertiesSchema.AccessSIP>.self)
+    XCTAssertTrue(attribute.valueType == Any.self)
+                  // Fixtures.CodablePropertiesSchema.AccessSIP.self)
     XCTAssertNotNil(attribute.valueTransformerName)
     XCTAssertEqual(attribute.valueTransformerName, transformerName.rawValue)
   }