CustomScalarType JSON example using AnyHashable fails due to Sendable requirement in v2

[AlexPan1992]

Question

extension MySchema {
    public enum CustomJSON: CustomScalarType, Hashable {
        case dictionary([String: AnyHashable])
        case array([AnyHashable])

        public init(_jsonValue value: JSONValue) throws {
            if let dict = value as? [String: AnyHashable] {
                self = .dictionary(dict)
            } else if let array = value as? [AnyHashable] {
                self = .array(array)
            } else {
                throw JSONDecodingError.couldNotConvert(value: value, to: CustomJSON.self)
            }
        }

        public var _jsonValue: JSONValue {
            switch self {
            case let .dictionary(json as AnyHashable),
                 let .array(json as AnyHashable):
                return json
            }
        }

        public static func == (lhs: CustomJSON, rhs: CustomJSON) -> Bool {
            lhs._jsonValue == rhs._jsonValue
        }

        public func hash(into hasher: inout Hasher) {
            hasher.combine(_jsonValue)
        }
    }
}

https://www.apollographql.com/docs/ios/custom-scalars#json-and-other-custom-scalars-with-multiple-return-types

CustomScalarType & JSONValue now requires conforming types to be Sendable, and AnyHashable cannot conform to Sendable.
This makes the documented example unusable in practice. A note or an updated example using a Sendable-compatible type would be very helpful.

[AlexPan1992]

I also saw the discussion in the comments of RFC: 2.0 API Changes – Swift Concurrency:

#3411 (comment)

It mentions the issue that AnyHashable cannot conform to Sendable, but I still don’t know how to resolve this problem in a CustomScalarType & JSONValue.

[AnthonyMDev]

Thanks for making this issue @AlexPan1992!

The import statement in the file needs to be update to:

@_spi(Execution) @_spi(Internal) import ApolloAPI

This is explained further in our 2.0 Migration Guide.

[github-actions]

Do you have any feedback for the maintainers? Please tell us by taking a one-minute survey. Your responses will help us understand Apollo iOS usage and allow us to serve you better.

[AlexPan1992]

Thanks for making this issue @AlexPan1992!

The import statement in the file needs to be update：

@_spi(Execution) @_spi(Internal) import ApolloAPI

This is explained further in our 2.0 Migration Guide.

Hi @AnthonyMDev

Thanks for the suggestion! I tried updating the import statement as you mentioned, but it didn’t work in my case.

[BobaFetters]

I know we had to move away from AnyHashable for things like our JSONValue typealias for this reason, and our typealias is now any Sendable & Hashable, so you could try that or use our JSONValue typealias to keep things cleaner.

[AnthonyMDev]

Ah I totally missed that part! @BobaFetters is correct. Was that able to help you resolve this?

[AlexPan1992]

Yes, the information provided by @BobaFetters was helpful.
Here’s the approach I tried:

I used mapValues { $0._jsonValue } from JSONEncodable to convert it into a JSONObject,
and also used AnySendableHashable.equatableCheck to write unit tests.

@_spi(Internal) @_spi(Execution) import ApolloAPI

public enum JSON: CustomScalarType, Hashable {

  case dictionary(JSONObject)

  public init(_jsonValue value: JSONValue) throws {
    if let dictionary = value as? JSONObject {
      self = .dictionary(dictionary)
    } else {
      throw JSONDecodingError.couldNotConvert(value: value, to: JSON.self)
    }
  }

  public var _jsonValue: JSONValue {
    switch self {
    case let .dictionary(jsonValue):
      return jsonValue as JSONValue
    }
  }

  public static func == (lhs: JSON, rhs: JSON) -> Bool {
    lhs._jsonValue.hashValue == rhs._jsonValue.hashValue
  }

  public func hash(into hasher: inout Hasher) {
    hasher.combine(_jsonValue)
  }
}

import AnyCodable
import ApolloGraphQL
@_spi(Internal) import ApolloAPI

extension Dictionary where Key == String, Value == AnyCodable {

  func convertJSON() -> JSON {
    let jsonObject = convertJSONEncodableDictionary().mapValues { $0._jsonValue }
    return .dictionary(jsonObject)
  }

  fileprivate func convertJSONEncodableDictionary() -> JSONEncodableDictionary {
    compactMapValues { convertToJSONEncodable($0.value) }
  }

  fileprivate func convertToJSONEncodable(_ value: Any) -> (any JSONEncodable)? {
    if let nestedDictionary = value as? [String: AnyCodable] {
      return nestedDictionary.convertJSONEncodableDictionary()
    } else if let jsonEncodableValue = value as? any JSONEncodable {
      return jsonEncodableValue
    } else {
      return nil
    }
  }

}

import AnyCodable
import XCTest
@_spi(Internal) import ApolloAPI
import ApolloGraphQL

final class DictionaryStringAnyCodableTests: XCTestCase {
  func testConvert_Value_To_AnyHashable() throws {
    let sut: [String: AnyCodable] = [
      "String": AnyCodable("123"),
      "Bool": AnyCodable(true),
      "Int": AnyCodable(Int(1)),
      "Int32": AnyCodable(Int32(32)),
      "Float": AnyCodable(Float(11)),
      "Double": AnyCodable(Int32(22)),
      "Array": AnyCodable(["1", "2"]),
      "Object": AnyCodable([
        "String": AnyCodable("123"),
        "Bool": AnyCodable(true),
        "Int": AnyCodable(Int(1)),
        "Int32": AnyCodable(Int32(32)),
        "Float": AnyCodable(Float(11)),
        "Double": AnyCodable(Int32(22)),
        "Array": AnyCodable(["1", "2"]),
        "Object": AnyCodable([
          "String": AnyCodable("123"),
          "Bool": AnyCodable(true),
          "Int": AnyCodable(Int(1)),
          "Int32": AnyCodable(Int32(32)),
          "Float": AnyCodable(Float(11)),
          "Double": AnyCodable(Int32(22)),
          "Array": AnyCodable(["1", "2"]),
          "Object": AnyCodable([
            "String": AnyCodable("123"),
            "Bool": AnyCodable(true),
            "Int": AnyCodable(Int(1)),
            "Int32": AnyCodable(Int32(32)),
            "Float": AnyCodable(Float(11)),
            "Double": AnyCodable(Int32(22)),
            "Array": AnyCodable(["1", "2"]),
          ])
        ])
      ]),
    ]

    let jsonEncodableResult: [String: any Sendable & Hashable] = [
      "String": "123" as any Sendable & Hashable,
      "Bool": true as any Sendable & Hashable,
      "Int": Int(1) as any Sendable & Hashable,
      "Int32": Int32(32) as any Sendable & Hashable,
      "Float": Float(11) as any Sendable & Hashable,
      "Double": Int32(22) as any Sendable & Hashable,
      "Array": ["1", "2"] as any Sendable & Hashable,
      "Object": [
        "String": "123" as any Sendable & Hashable,
        "Bool": true as any Sendable & Hashable,
        "Int": Int(1) as any Sendable & Hashable,
        "Int32": Int32(32) as any Sendable & Hashable,
        "Float": Float(11) as any Sendable & Hashable,
        "Double": Int32(22) as any Sendable & Hashable,
        "Array": ["1", "2"] as any Sendable & Hashable,
        "Object": [
          "String": "123" as any Sendable & Hashable,
          "Bool": true as any Sendable & Hashable,
          "Int": Int(1) as any Sendable & Hashable,
          "Int32": Int32(32) as any Sendable & Hashable,
          "Float": Float(11) as any Sendable & Hashable,
          "Double": Int32(22) as any Sendable & Hashable,
          "Array": ["1", "2"] as any Sendable & Hashable,
          "Object": [
            "String": "123" as any Sendable & Hashable,
            "Bool": true as any Sendable & Hashable,
            "Int": Int(1) as any Sendable & Hashable,
            "Int32": Int32(32) as any Sendable & Hashable,
            "Float": Float(11) as any Sendable & Hashable,
            "Double": Int32(22) as any Sendable & Hashable,
            "Array": ["1", "2"] as any Sendable & Hashable,
          ] as any Sendable & Hashable
        ] as any Sendable & Hashable
      ] as any Sendable & Hashable
    ]

    let sutJSONValue = sut.convertJSON()._jsonValue
    let jsonEncodableResultJSONValue = JSON.dictionary(jsonEncodableResult)._jsonValue
    let result = AnySendableHashable.equatableCheck(sutJSONValue, jsonEncodableResultJSONValue)
    XCTAssertTrue(result)
  }
}