I have a structure that contains another structures and arrays.
public struct Report: Codable {
let s:Student;
let vio:[VIO];
let stuPresence: [StuPresence];
}
I am trying new JSONDecoder() to transform alamofire response into my struct.
sessionManager.request( self.url_report+"?d="+date, method: .get, parameters: nil).responseJSON{ response in
if response.response?.statusCode == 200 {
debugPrint(response)
do{
let r = try JSONDecoder().decode(Report.self, from: response.result.value as! Data)
debugPrint(r);
}catch{
self.showMessage(message: self.general_err)
}
}
}
The problem is that instead of strings after decoding in my Report struct I get numbers (checked from debugging mode). What am I doing wrong?
UPDATE: it also gives error
Could not cast value of type '__NSDictionaryI' (0x108011508) to 'NSData' (0x108010090)
The error is pretty clear:
response.result.value is obviously a dictionary (__NSDictionaryI) which cannot be casted to (NS)Data. That means that the JSON is already deserialized.
To be able to use JSONDecoder you have to change your Alamofire settings to return raw Data
Related
This question already has answers here:
Decoding Error -- Expected to decode Dictionary<String, Any> but found an array instead
(2 answers)
Closed 1 year ago.
I'm working on a creative project, and I'm trying to decode content from an API database using Swift's JSONDecoder() function. I've built my structs, a getData() function, and I've set up a do-try-catch for the JSONDecoder() function. I'm having difficulty understanding what I'm doing to get the error I'm getting.
Here are my structs:
struct Response: Codable {
let foundRecipes: [Recipe]
let foundIngredients: [Ingredient]
}
struct Recipe: Codable {
let id: Int
let title: String
let image: String
let imageType: String
let usedIngredientCount: Int
let missedIngredientCount: Int
let missedIngredients: [Ingredient]
let usedIngredients: [Ingredient]
let unusedIngredients: [Ingredient]
let likes: Int
}
struct Ingredient: Codable {
let id: Int
let amount: Int
let unit: String
let unitLong: String
let unitShort: String
let aisle: String
let name: String
let original: String
let originalString: String
let origianalName: String
let metaInformation: [String]
let meta: [String]
let image: String
}
Here's my getData() function:
func getData(from url: String) {
URLSession.shared.dataTask(with: URL(string: url)!, completionHandler: { data, response, error in
guard let data = data, error == nil else {
print("something went wrong.")
return
}
var result: Response?
do {
result = try JSONDecoder().decode(Response.self, from: data)
}
catch {
print("")
print(String(describing: error)) // Right here is where the error hits.
}
guard let json = result else {
return
}
print(json.foundRecipes)
}).resume()
}
Here's a link to the API's documentation. The URL I'm calling in getData() links to the same structure of search as shown in their example: https://spoonacular.com/food-api/docs#Search-Recipes-by-Ingredients — and here's a screenshot of the url results for the exact search I'm working on: https://imgur.com/a/K3Rn9SZ
And finally, here's the full error that I'm catching:
typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Dictionary<String, Any> but found an array instead.", underlyingError: nil))
My understanding of this error is that it's saying I told the JSONDecoder() to look for a Dictionary of <String, Any>, but it's at the link and only seeing an array. I'm confused, because I don't know where it thinks I'm providing a dictionary. Where am I screwing up? Not looking for specific code changes, just some guidance on what I'm missing.
Thanks in advance :)
As you can see in your image of the API data and in the API documentation you linked to, the API is returning an array (in the documentation, for example, you can see that it is surrounded by [...]). In fact, it looks like the API returns an array of Recipe.
So, you can change your decoding call to this:
var result: [Recipe]?
do {
result = try JSONDecoder().decode([Recipe].self, from: data)
print(result)
} catch {
print(error)
}
Perhaps your idea for Response came from somewhere else, but the keys foundRecipes or foundIngredients don't show up in this particular API call.
Also, thanks to #workingdog's for a useful comment about changing amount to a Double instead of an Int in your model.
I'm fairly new to this. Anyway, here we go:
I have JSON data that comes from an API. For the sake of this question, I have simplified it greatly. You can run the following code in a Playground.
import UIKit
struct Book: Codable {
let image: String
}
// this comes from my API
let jsonString = "{ \"image\" = \"someURL\" }"
print(jsonString) // { "image" = "someURL" }
// convert String to Data
let jsonData = jsonString.data(using: .utf8)
// decode data (in my project, I catch the error, of course)
let decoder = JSONDecoder()
let decodingResult = try? decoder.decode(Book.self, from: jsonData!)
print(decodingResult) // nil
As you can see, I'm trying to decode my JSON-String into an Object (my Struct), but the Decoder always returns nil.
Can someone point me in the right direction?
Thank you.
Your current jsonString isn't a proper JSON. Change it to "{ \"image\": \"someURL\" }", and it should work. For more information on JSON syntax, check this manual.
I want to update my code in the past when I used swift 2 or 3. I am stuck where I want to use Alamofire but the way to use it changed and I don't know how to use it anymore. Can anybody update this part of the code and explain a little bit? Thank you.
This is the original code.
Alamofire.request(.POST, url)
.response{ (request, response, data, error) in
let xml = SWXMLHash.parse(data!)
let sunsetTime = xml["result"]["rise_and_set"]["sunset_hm"].element?.text
self.sunsetTimeLabel.text = sunsetTime
self.getDateFromString(sunsetTime,year: comp.year,month: comp.month,day: comp.day)
if (error != nil) {
print(error)
}
}
this is the code I was writing.
AF.request(url, method: .post).responseJSON { (responseData) in
let xml = SWXMLHash.parse(responseData as Data)
let sunsetTime = xml["result"]["rise_and_set"]["sunset_hm"].element?.text
self.sunsetTimeLabel.text = sunsetTime
There is an error saying "Cannot convert value of type 'AFDataResponse' (aka 'DataResponse') to type 'Data' in coercion"
Your first code snippet is Alamofire 3 syntax. I infer from the second code snippet that you are now using Alamofire 5.
There are a few issues:
You are calling responseJSON (which you’d only use if your response was JSON, not XML). Use response or, better, responseData.
The response object passed to this closure is not a Data, itself. In the case of responseData method, it is a AFDataResponse object, which has a data property (which is a Data?). You have to extract the Data object from this AFDataResponse, either by unwrapping the contents of the data property, or from the result (see next point).
You should probably check for success or failure and extract the Data from the response.result object.
So, pulling this together, you end up with something like:
AF.request(url, method: .post).responseData { response in
switch response.result {
case .failure(let error):
print(error)
case .success(let data):
let xml = SWXMLHash.parse(data)
...
}
}
According to the JSON standard RFC 7159, this is valid json:
22
How do I decode this into an Int using swift4's decodable? This does not work
let twentyTwo = try? JSONDecoder().decode(Int.self, from: "22".data(using: .utf8)!)
It works with good ol' JSONSerialization and the .allowFragments
reading option. From the documentation:
allowFragments
Specifies that the parser should allow top-level objects that are not an instance of NSArray or NSDictionary.
Example:
let json = "22".data(using: .utf8)!
if let value = (try? JSONSerialization.jsonObject(with: json, options: .allowFragments)) as? Int {
print(value) // 22
}
However, JSONDecoder has no such option and does not accept top-level
objects which are not arrays or dictionaries. One can see in the
source code that the decode() method calls
JSONSerialization.jsonObject() without any option:
open func decode<T : Decodable>(_ type: T.Type, from data: Data) throws -> T {
let topLevel: Any
do {
topLevel = try JSONSerialization.jsonObject(with: data)
} catch {
throw DecodingError.dataCorrupted(DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: error))
}
// ...
return value
}
In iOS 13.1+ and macOS 10.15.1+ JSONDecoder can handle primitive types on root level.
See the latest comments (Oct 2019) in the linked article underneath Martin's answer.
Has you can see from my previous questions, I got a lot of trouble parsing JSON Data. After few days of headache with that, I think the best way still to use alamofire/swiftyjson. I also found the alamofire-swiftyjson to let everything working well together.
But I am not sure how to install this three "libraries" together.
I download the whole Alamofire pack inside my project, I add the SwiftyJson.swift in my project and finally download the Alamofire-SwiftyJson in my project.
But when I change my alamofire request with "responseSwiftyJSON" I get an error saying " "Request" does not have a member name "responseSwiftyJSON
Alamofire.request(.GET, "http://mysiteweb.com/app/data/jsonpersodata.php", parameters: ["username": username]).responseSwiftyJSON { (request, response, data, error)
Add Alamofire and SwiftyJSON to the project. Then you can use Alamofire to request the data from the server and SwiftyJSON for serialization.
Alamofire 4
Alamofire.request(url).responseJSON { response in
guard let data = response.data else {
// No data returned
return
}
let json = JSON(data: data)
print(json)
}
Alamofire 3
Alamofire.request(.GET, url).validate().responseJSON { response in
switch response.result {
case .Success:
if let jsonData = response.result.value {
let json = JSON(jsonData)
print(json)
}
case .Failure(let error):
print(error)
}
}
Alamofire 2
Alamofire.request(.GET, "http://api.example.com", parameters: ["username" : username])
.responseJSON { request, response, data, error in
let swiftyJSONObject = JSON(data: data!)
}
Note that you have to unwrap data because server may return nothing.