`Codable` conformance modify generated camel-cased `Swift` fields from `serde`

[setoelkahfi]

I managed to be able to generate the Codable conformance in swift binding (with generate_codable_conformance = true option) with cargo swift, but the generated fields are camelCased by default, so the parsing is failed.:

#[derive(Serialize, Deserialize, Debug, Record)]
#[tsync]
pub struct ContentResponse {
    pub code: i32,
    pub message: String,
    #[serde(rename = "songProviders")] // Doesn't work
    pub song_providers: Vec<SongProvider>,
}

Swift generated code:

public struct ContentResponse {
    public var code: Int32
    public var message: String
    public var songProviders: [SongProvider]

    // Default memberwise initializers are never public by default, so we
    // declare one manually.
    public init(code: Int32, message: String, songProviders: [SongProvider]) {
        self.code = code
        self.message = message
        self.songProviders = songProviders
    }
}

#if compiler(>=6)
extension ContentResponse: Sendable {}
#endif


extension ContentResponse: Equatable, Hashable {
    public static func ==(lhs: ContentResponse, rhs: ContentResponse) -> Bool {
        if lhs.code != rhs.code {
            return false
        }
        if lhs.message != rhs.message {
            return false
        }
        if lhs.songProviders != rhs.songProviders {
            return false
        }
        return true
    }

    public func hash(into hasher: inout Hasher) {
        hasher.combine(code)
        hasher.combine(message)
        hasher.combine(songProviders)
    }
}

extension ContentResponse: Codable {}

That shouldn't be a problem if the Codable conformance provides the CodingKeys that handle said behaviour. Docs.

My uniffi.toml file:

[bindings.swift]
generate_codable_conformance = true

I cannot make the full networking layer of my app work with uniffi with tokio and reqwest, so I'm trying to at least reuse the data model. My setup is that I have a workspace with main package is the network layer (reqwest + tokio + uniffi), and a model crate with the data model used by the main crate:

crate_networking
- crates
   - model
      - src
         Cargo.toml
         uniffi.toml
- CrateNetworking // cargo swift package
- generated // uniffi
- src
Cargo.toml

Any way to keep the snake case field by default?

[mhammond]

That sounds like a simple bug in uniffi - can you please give more context or an example of what's going wrong for you?

[setoelkahfi]

I updated the question.

[setoelkahfi]

I tried to override the Codable conformances for my Record types like so:

public struct ContentResponse {
    public var code: Int32
    public var message: String
    public var songProviders: [SongProvider]

    // Default memberwise initializers are never public by default, so we
    // declare one manually.
    public init(code: Int32, message: String, songProviders: [SongProvider]) {
        self.code = code
        self.message = message
        self.songProviders = songProviders
    }
}
// ---
// More conformances and generated code 
// ---

extension ContentResponse: Codable {
    enum CodingKeys: String, CodingKey {
        case code, message, songProviders = "song_providers"
    }
}

extension SongProvider: Codable {
    enum CodingKeys: String, CodingKey {
        case id, name, description, claimed
        case providerId = "provider_id"
        case providerType = "provider_type"
        case imageUrl = "image_url"
        case audioFile = "audio_file"
        case audioFileStatus = "audio_file_status"
        case createdAt = "crated_at"
        case updatedAt = "updated_at"
    }
}

extension AudioFile: Codable {
    enum CodingKeys: String, CodingKey {
        case id, name, status, results
        case imageUrl = "image_url"
        case audioMetadata = "audio_metadata"
    }
}

extension User: Codable {
    enum CodingKeys: String, CodingKey {
        case id, email, username, name, about
        case gravatarUrl = "gravatar_url"
        case followersCount = "followers_count"
        case followingCount = "following_count"
        case favoriteAudioFiles = "favorite_audio_files"
        case semitoneBalance = "semitone_balance"
    }
}

extension ResultFile: Codable {
    enum CodingKeys: String, CodingKey {
        case id, filename, onset, user
        case sourceFile = "source_file"
        case audioFileId = "audio_file_id"
    }
}

Now I get Expected to decode Dictionary<String, Any> but found a string instead. error.

My Swift networking code:

import Foundation
import CrateNetworking

func carousel(
    apiHost: String,
    limit: Int32,
    offset: Int32
) async throws -> ContentResponse {
    /// Configure the URL for our request.
    let url = URL(string: "https://\(apiHost)/api/v1/carousel?limit=\(limit)&offset=\(offset)")!
    
    /// Create a URLRequest for the POST request.
    var request = URLRequest(url: url)
    
    /// Configure the HTTP method.
    request.httpMethod = "GET"

    /// Configure the proper content-type value to JSON.
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    
    /// Use URLSession to fetch the data asynchronously.
    let (data, _) = try await URLSession.shared.data(for: request)
    
    print(data.prettyPrintedJSONString ?? "Couldn't create a .json string.")
    
    /// Decode the JSON response
    let decodedResponse = try JSONDecoder().decode(ContentResponse.self, from: data)
    
    return decodedResponse
}

[Sajjon]

My Swift networking code:

import Foundation
import CrateNetworking

func carousel(
apiHost: String,
limit: Int32,
offset: Int32
) async throws -> ContentResponse {
...
}

Please paste the raw JSON so that we can debug it, thanks!

[setoelkahfi]

@Sajjon there you go

{
  "code": 200,
  "message": "OK",
  "song_providers": [
    {
      "id": 13461,
      "user_id": 407,
      "song_id": null,
      "provider_id": "4wOS66tqt0eidueOYSAHv5",
      "provider_type": "spotify",
      "name": "Buurman",
      "preview_url": "https://p.scdn.co/mp3-preview/79b32a86de2d7f6bb513f79fdc71b8158de71e92?cid=01ed55117d294377aef8716d4e057a42",
      "created_at": "2023-09-02T21:25:44.458Z",
      "updated_at": "2023-09-02T21:25:44.458Z",
      "description": null,
      "image_url": null,
      "status": "published",
      "song_provider_group_id": null,
      "audio_file_status": "idle",
      "claimed": false,
      "audio_file": null,
      "path": "/id-id/songs-bridge/buurman-13461",
      "type": "Jembatan lagu",
      "created": "kurang lebih 2 tahun yang lalu"
    },
    {
      "id": 18372,
      "user_id": 1397,
      "song_id": null,
      "provider_id": "001VMKfkHZrlyj7JlQbQFL",
      "provider_type": "spotify",
      "name": "Await The King's Justice",
      "preview_url": null,
      "created_at": "2024-02-29T23:52:26.601Z",
      "updated_at": "2024-02-29T23:52:26.601Z",
      "description": null,
      "image_url": null,
      "status": "published",
      "song_provider_group_id": null,
      "audio_file_status": "idle",
      "claimed": false,
      "audio_file": null,
      "path": "/id-id/songs-bridge/await-the-king-s-justice-18372",
      "type": "Jembatan lagu",
      "created": "lebih dari 1 tahun yang lalu"
    }
  ]
}

I have working apps using Swift conformances directly now instead of generated conformances from uniffi. So, at least I can reuse the types.

I tried digging into the the RecordTemplate.swift file, I think the Codable conformance needs custom handling to overcome the snake case to camel case nature of Rust and Swift.

[Sajjon]

@setoelkahfi you made a typo in your JSON key overwrite case createdAt = "crated_at"

This unit test passed:

Click me

import Testing
import Foundation

@Test func example() async throws {
    let data = json.data(using: .utf8)!
    let model = try JSONDecoder().decode(ContentResponse.self, from: data)
    #expect(model.songProviders.count == 2)
}

public struct SongProvider {
    let id: Int
    let name: String
    let description: String?
    let claimed: Bool
    let providerId: String
    let providerType: String
    let imageUrl: String?
    let audioFile: String?
    let audioFileStatus: String
    let createdAt: String
    let updatedAt: String
}

public struct ContentResponse {
    public var code: Int32
    public var message: String
    public var songProviders: [SongProvider]

    // Default memberwise initializers are never public by default, so we
    // declare one manually.
    public init(code: Int32, message: String, songProviders: [SongProvider]) {
        self.code = code
        self.message = message
        self.songProviders = songProviders
    }
}
// ---
// More conformances and generated code
// ---

extension ContentResponse: Codable {
    enum CodingKeys: String, CodingKey {
        case code, message, songProviders = "song_providers"
    }
}

extension SongProvider: Codable {
    enum CodingKeys: String, CodingKey {
        case id, name, description, claimed
        case providerId = "provider_id"
        case providerType = "provider_type"
        case imageUrl = "image_url"
        case audioFile = "audio_file"
        case audioFileStatus = "audio_file_status"
        case createdAt = "created_at"
        case updatedAt = "updated_at"
    }
}

struct AudioFile {
    let id: Int
    let name: String
    let status: String
    let results: String
    let imageUrl: String
    let audioMetadata: String
}

extension AudioFile: Codable {
    enum CodingKeys: String, CodingKey {
        case id, name, status, results
        case imageUrl = "image_url"
        case audioMetadata = "audio_metadata"
    }
}

struct User {
    let id: Int
    let email: String
    let username: String
    let name: String
    let about: String
    let gravatarUrl: String
    let followersCount: String
    let followingCount: String
    let favoriteAudioFiles: String
    let semitoneBalance: String
}

extension User: Codable {
    enum CodingKeys: String, CodingKey {
        case id, email, username, name, about
        case gravatarUrl = "gravatar_url"
        case followersCount = "followers_count"
        case followingCount = "following_count"
        case favoriteAudioFiles = "favorite_audio_files"
        case semitoneBalance = "semitone_balance"
    }
}

struct ResultFile {
    let id: String
    let filename: String
    let onset: String
    let user: String
    let sourceFile: String
    let audioFileId: String
}

extension ResultFile: Codable {
    enum CodingKeys: String, CodingKey {
        case id, filename, onset, user
        case sourceFile = "source_file"
        case audioFileId = "audio_file_id"
    }
}


private let json = """
{
  "code": 200,
  "message": "OK",
  "song_providers": [
    {
      "id": 13461,
      "user_id": 407,
      "song_id": null,
      "provider_id": "4wOS66tqt0eidueOYSAHv5",
      "provider_type": "spotify",
      "name": "Buurman",
      "preview_url": "https://p.scdn.co/mp3-preview/79b32a86de2d7f6bb513f79fdc71b8158de71e92?cid=01ed55117d294377aef8716d4e057a42",
      "created_at": "2023-09-02T21:25:44.458Z",
      "updated_at": "2023-09-02T21:25:44.458Z",
      "description": null,
      "image_url": null,
      "status": "published",
      "song_provider_group_id": null,
      "audio_file_status": "idle",
      "claimed": false,
      "audio_file": null,
      "path": "/id-id/songs-bridge/buurman-13461",
      "type": "Jembatan lagu",
      "created": "kurang lebih 2 tahun yang lalu"
    },
    {
      "id": 18372,
      "user_id": 1397,
      "song_id": null,
      "provider_id": "001VMKfkHZrlyj7JlQbQFL",
      "provider_type": "spotify",
      "name": "Await The King's Justice",
      "preview_url": null,
      "created_at": "2024-02-29T23:52:26.601Z",
      "updated_at": "2024-02-29T23:52:26.601Z",
      "description": null,
      "image_url": null,
      "status": "published",
      "song_provider_group_id": null,
      "audio_file_status": "idle",
      "claimed": false,
      "audio_file": null,
      "path": "/id-id/songs-bridge/await-the-king-s-justice-18372",
      "type": "Jembatan lagu",
      "created": "lebih dari 1 tahun yang lalu"
    }
  ]
}
"""

[setoelkahfi]

@setoelkahfi you made a typo in your JSON key overwrite case createdAt = "crated_at"

This unit test passed:

Click me

Thanks for debugging it. It apparently the enum parsing that caused the error. But now I got the same error for my LoginResponse. I think I'll keep my Swift Codable conformance version for now. It's still too unstable to use the generated one.

Swift enum Codable conformance

ProviderType:

extension ProviderType: Codable {

    public func encode(to encoder: any Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case .youtube:
            try container.encode("youtube")
        case .spotify:
            try container.encode("spotify")
        case .apple:
            try container.encode("apple")
        }
    }

    public init(from decoder: any Decoder) throws {
        let container = try decoder.singleValueContainer()
        let value = try container.decode(String.self)

        switch value.lowercased() {
        case "youtube":
            self = .youtube
        case "spotify":
            self = .spotify
        case "apple":
            self = .apple
        default:
            throw DecodingError.dataCorruptedError(
                in: container,
                debugDescription: "Invalid ProviderType value: \(value)"
            )
        }
    }
}

AudioFileStatus:

extension AudioFileStatus: Codable {

    public func encode(to encoder: any Encoder) throws {
        var container = encoder.singleValueContainer()
        switch self {
        case .idle:
            try container.encode("idle")
        case .processing:
            try container.encode("processing")
        case .error:
            try container.encode("error")
        case .done:
            try container.encode("done")
        }
    }

    public init(from decoder: any Decoder) throws {
        let container = try decoder.singleValueContainer()
        let value = try container.decode(String.self)

        switch value.lowercased() {
        case "idle":
            self = .idle
        case "processing":
            self = .processing
        case "error":
            self = .error
        case "done":
            self = .done
        default:
            throw DecodingError.dataCorruptedError(
                in: container,
                debugDescription: "Invalid AudioFileStatus value: \(value)"
            )
        }
    }
}

`LoginResponse` struct

/**
 * Install tsync with cargo install tsync.
 * Regenerate this file from the crate_networking directory.
 * Regenerate for splitfire-desktop and splitfire-web.
 * Command:
 * `tsync -i ./src -o ./../../frontend/splitfire-desktop/lib/crate_networking/types.ts`
 * `tsync -i ./src -o ./../../frontend/splitfire-web/lib/crate_networking/types.ts``
 */
public struct LoginResponse {
    public var code: Int32
    public var message: String
    public var accessToken: String?
    public var user: User?

    // Default memberwise initializers are never public by default, so we
    // declare one manually.
    public init(code: Int32, message: String, accessToken: String?, user: User?) {
        self.code = code
        self.message = message
        self.accessToken = accessToken
        self.user = user
    }
}

// More code

extension LoginResponse: Codable {
    enum CodingKeys: String, CodingKey {
        case code, message, accessToken = "access_token", user
    }
}

{
  "message" : "OK",
  "user" : {
    "followers_count" : 12,
    "semitone_balance" : 6400,
    "favorite_audio_files" : [
      {
        "status" : "done",
        "length" : 80.256009070000005,
        "id" : 291,
        "created_at" : "2024-08-10T21:56:32.319Z",
        "song_provider_id" : 8066,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/nvPlHk4Xpvo\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:50:14.741Z",
        "progress" : 100,
        "name" : "Dewa - 1000 Bintang | Official Audio",
        "audio_metadata" : {
          "length" : {
            "seconds" : 80.256009070000005,
            "milliseconds" : 80256.00907,
            "mmss" : "01:20"
          }
        }
      },
      {
        "status" : "done",
        "length" : 54.066666669999996,
        "id" : 311,
        "created_at" : "2024-08-20T06:34:41.897Z",
        "song_provider_id" : 21764,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/lXuwcDEORPM\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:50:35.546Z",
        "progress" : 100,
        "name" : "1000 Bintang",
        "audio_metadata" : {
          "length" : {
            "seconds" : 54.066666669999996,
            "milliseconds" : 54066.666669999999,
            "mmss" : "00:54"
          }
        }
      },
      {
        "status" : "done",
        "length" : 211.33333332999999,
        "id" : 324,
        "created_at" : "2024-08-24T05:45:55.689Z",
        "song_provider_id" : 16625,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/yCZlVXl_Vu4\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:49:48.989Z",
        "progress" : 100,
        "name" : "Siapa Yang Pantas",
        "audio_metadata" : {
          "length" : {
            "seconds" : 211.33333332999999,
            "milliseconds" : 211333.33332999999,
            "mmss" : "03:31"
          }
        }
      },
      {
        "status" : "done",
        "length" : 206.17333332999999,
        "id" : 325,
        "created_at" : "2024-08-24T06:08:09.306Z",
        "song_provider_id" : 16675,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/Bwa7XYeqpwE\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:50:22.253Z",
        "progress" : 100,
        "name" : "Outsider",
        "audio_metadata" : {
          "length" : {
            "seconds" : 206.17333332999999,
            "milliseconds" : 206173.33332999999,
            "mmss" : "03:26"
          }
        }
      },
      {
        "status" : "done",
        "length" : 204.74666667,
        "id" : 302,
        "created_at" : "2024-08-13T17:19:24.081Z",
        "song_provider_id" : 21380,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/pQpIkMiYQHw\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:50:51.817Z",
        "progress" : 100,
        "name" : "Sk8er Boi",
        "audio_metadata" : {
          "length" : {
            "seconds" : 204.74666667,
            "milliseconds" : 204746.66667000001,
            "mmss" : "03:24"
          }
        }
      },
      {
        "status" : "done",
        "length" : 324.39999999999998,
        "id" : 327,
        "created_at" : "2024-08-24T06:46:36.698Z",
        "song_provider_id" : 16971,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/GAZ6GRO_1wE\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:50:22.578Z",
        "progress" : 100,
        "name" : "Dua Sedjoli",
        "audio_metadata" : {
          "length" : {
            "seconds" : 324.39999999999998,
            "milliseconds" : 324400,
            "mmss" : "05:24"
          }
        }
      },
      {
        "status" : "done",
        "length" : 231.93333333000001,
        "id" : 328,
        "created_at" : "2024-08-25T22:00:42.226Z",
        "song_provider_id" : 17636,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/ZHLNudYcQ0c\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:50:06.354Z",
        "progress" : 100,
        "name" : "The Zephyr Song",
        "audio_metadata" : {
          "length" : {
            "seconds" : 231.93333333000001,
            "milliseconds" : 231933.33333000002,
            "mmss" : "03:51"
          }
        }
      },
      {
        "status" : "done",
        "length" : 217.52458050000001,
        "id" : 344,
        "created_at" : "2024-09-01T15:05:45.601Z",
        "song_provider_id" : 21792,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/zgvKBDvLwC0\/hqdefault.jpg",
        "updated_at" : "2024-09-01T17:20:44.240Z",
        "progress" : 100,
        "name" : "Voices",
        "audio_metadata" : {
          "length" : {
            "seconds" : 217.52458050000001,
            "milliseconds" : 217524.58050000001,
            "mmss" : "03:37"
          }
        }
      },
      {
        "status" : "done",
        "length" : 209.36000000000001,
        "id" : 348,
        "created_at" : "2024-09-09T20:42:21.437Z",
        "song_provider_id" : 21804,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/jdMexFig-JA\/hqdefault.jpg",
        "updated_at" : "2024-09-09T21:07:04.294Z",
        "progress" : 100,
        "name" : "Radio",
        "audio_metadata" : {
          "length" : {
            "seconds" : 209.36000000000001,
            "milliseconds" : 209360,
            "mmss" : "03:29"
          }
        }
      },
      {
        "status" : "done",
        "length" : 269,
        "id" : 323,
        "created_at" : "2024-08-24T04:29:17.067Z",
        "song_provider_id" : 16704,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/D4INE2zO9OU\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:49:52.805Z",
        "progress" : 100,
        "name" : "Can't Stop",
        "audio_metadata" : {
          "length" : {
            "seconds" : 269,
            "milliseconds" : 269000,
            "mmss" : "04:29"
          }
        }
      },
      {
        "status" : "done",
        "length" : 223.5,
        "id" : 345,
        "created_at" : "2024-09-01T18:06:44.643Z",
        "song_provider_id" : 21837,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/VWuRAOaZghE\/hqdefault.jpg",
        "updated_at" : "2024-09-05T16:42:49.521Z",
        "progress" : 100,
        "name" : "Film Favorit",
        "audio_metadata" : {
          "length" : {
            "seconds" : 223.5,
            "milliseconds" : 223500,
            "mmss" : "03:43"
          }
        }
      },
      {
        "status" : "done",
        "length" : 244.89333332999999,
        "id" : 330,
        "created_at" : "2024-08-27T18:58:08.894Z",
        "song_provider_id" : 21401,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/mHSfJq8X0Kg\/hqdefault.jpg",
        "updated_at" : "2024-08-30T10:49:46.887Z",
        "progress" : 100,
        "name" : "Aku Percaya Kamu",
        "audio_metadata" : {
          "length" : {
            "seconds" : 244.89333332999999,
            "milliseconds" : 244893.33332999999,
            "mmss" : "04:04"
          }
        }
      },
      {
        "status" : "done",
        "length" : 201.26666667000001,
        "id" : 334,
        "created_at" : "2024-08-30T09:18:12.528Z",
        "song_provider_id" : 16997,
        "image_url" : "https:\/\/i.ytimg.com\/vi\/_myRrkpR9_0\/hqdefault.jpg",
        "updated_at" : "2024-08-30T09:30:17.574Z",
        "progress" : 100,
        "name" : "Fortune Faded",
        "audio_metadata" : {
          "length" : {
            "seconds" : 201.26666667000001,
            "milliseconds" : 201266.66667000001,
            "mmss" : "03:21"
          }
        }
      }
    ],
    "id" : 1,
    "email" : "setoelkahfi@gmail.com",
    "username" : "setoelkahfi",
    "following_count" : 14,
    "about" : "Lha opo",
    "name" : "Seto",
    "gravatar_url" : "https:\/\/secure.gravatar.com\/avatar\/70dbaf4b2a2b682c8b26aedf82b498e2"
  },
  "code" : 200
}

Feel free to close this issue if it's not relevant anymore.