The server I'm talking to expects a message in the format:
{
"command": "subscribe",
"identifier": "{\"channel\": \"UserChannel\"}",
"data": "{\"key\": \"value\"}"
}
Where the identifier and data values is an escaped json string.
I have this so far:
struct ActionCableMessage<Message: Encodable>: Encodable {
let command: Command
let identifier: CableChannel
let data: Message?
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(command, forKey: .command)
try container.encode(identifier, forKey: .identifier) // ????
}
private enum CodingKeys: String, CodingKey {
case command, identifier, data
}
}
But I don't know what to do from here. I think I need a protocol that CableChannel and Message can conform to, with a provided extension func that implements encode (to encoder: Encoder), which ensures Encoder must be a JSONEncoder, and if so, uses that to rewrite it's own value as a escaped json string.
I also need to decode this back to the ActionCableMessage struct, but I haven't gotten that far yet.
I think I need a protocol that CableChannel and Message can conform to
Well, that protocol is Encodable (or Codable if you prefer).
// just implement these as you normally would
extension CableChannel : Encodable { ... }
extension Message : Encodable { ... }
Then in ActionCableMessage, you use another encoder to encode the inner objects to JSON data, then convert that to string, then encode that string:
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(command, forKey: .command)
let subencoder = JSONEncoder()
let identifierString = try String(data: subencoder.encode(identifer), encoding: .utf8)
try container.encode(identifierString, forKey: .identifier)
// do the same for "data"
}
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