Swift 4 generics with struct - swift

Question

I'm trying to use generics with Codable protocol, but I'm getting an error.
Cannot invoke 'decode' with an argument list of type '([T.Type], from: Data)
static func getRequest<T>(model: T.Type, url: String, parameters: [String: Any]? = nil, headers: [String: String]? = nil, data: #escaping (Any?, Any?, Error?) -> ()) -> Alamofire.DataRequest {
return Alamofire.request(url, method: .get, parameters: parameters, encoding: URLEncoding.default, headers: headers)
.validate(contentType: [RequestHelper.HeaderKeys.contentTypeJson])
.responseJSON { (response) in
print(response)
switch response.result {
case .success:
let responseData = response.data!
do {
print(model)
print(T.self)
let decodable = try JSONDecoder().decode([model].self, from: responseData)
data(response.response?.allHeaderFields, decodable, nil)
} catch let error {
data(nil, nil, error)
}
case .failure(let requestError):
data(nil, nil, requestError)
print(requestError)
}
}
}
I need pass my struct model to this method
How can I fix this? Does anyone could help me?

Answer 1

decode() can only take a type that is Decodable. You need to specify that in your method signature. Either add where T: Decodable at the end of getRequest's declaration or just put <T: Decodable> inside the brackets to restrict T to decodable types only, and then you should be able to pass your parameter to decode().
EDIT: Looking at your code, there's another error:
let decodable = try JSONDecoder().decode([model].self, from: responseData)
Instead of [model].self, you need to pass [T].self. Otherwise you're passing an array of types rather than the type of an array.