I want to encode Dictionary to json with JSONEncoder. It seems like a Request, receive a dictionary as parameter and encode it to json as http body. The code is looks like this:
let dict = ["name": "abcde"]
protocol Request {
var params: [String: Encodable] { get set }
func encode<T>(_ value: T) throws -> Data where T : Encodable
}
extension Request {
func encode<T>(_ value: T) throws -> Data where T : Encodable {
return try JSONEncoder().encode(value)
}
var body: Data? {
if let encoded = try? self.encode(self.params) {
return encoded
}
return nil
}
}
struct BaseRequest: Request {
var params: [String : Encodable]
}
let req = BaseRequest(params: dict)
let body = req.body
But this code occurs error
Fatal error: Dictionary<String, Encodable> does not conform to Encodable because Encodable does not conform to itself. You must use a concrete type to encode or decode.
How could I make this encodable?
You have to introduce type erasure as follows:
struct AnyEncodable: Encodable {
let value: Encodable
init(value: Encodable) {
self.value = value
}
func encode(to encoder: Encoder) throws {
try value.encode(to: encoder)
}
}
struct Model: Encodable {
var params: [String: AnyEncodable]
}
let encoder = JSONEncoder()
encoder.outputFormatting = .prettyPrinted
let json = try! encoder.encode(
Model(
params: [
"hello" : AnyEncodable.init(value: "world")
]
).params
)
print(String(data: json, encoding: .utf8))
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