Store and Fetch an array

[sylvan-d-ash]

I would like to know how to store and subsequently fetch an array. I've got the following models:

struct World: Codable {
    var regions: [Region]
}

struct Region: Codable {
    var name: String
    var numberOfCountries: Int
    
    /// specify the keys in the JSON from the API
    private enum CodingKeys: String, CodingKey {
        case name = "regionName"
        case numberOfCountries = "nrCountries"
    }
    
    public init(from decoder: Decoder) throws {
        let values = try decoder.container(keyedBy: CodingKeys.self)
        let number = try values.decode(String.self, forKey: .numberOfCountries)
        
        numberOfCountries = Int(number) ?? 0
        name = try values.decode(String.self, forKey: .name)
    }
}

I'm saving the World info like:

let regions = [Region(name: "Europe", numberOfCountries: 21), Region(name: "Asia", numberOfCountries: 54)]
let world = World(regions: regions)
try self.storage?.setObject(world, forKey: "Constants.World")

And trying to fetch this data later on like:

do {
    let world = try storage.object(ofType: World.self, forKey: "Constants.World")
} catch {
    print("\(error.localizedDescription)")
}

The saving seems to work OK, but I get the following error whenever I try to fetch the data from the cache: The data couldn’t be read because it isn’t in the correct format.

Any idea what I could be doing wrong? Or how should I save the above data?

[onmyway133]

@sylvan-d-ash Hi, when you load, can you try

let world = try storage.object(ofType: [World].self, forKey: "Constants.World")

Basically, use [World].self instead of World.self. Also you save as [Region] but you load with World?

[markhao-cb]

Hi @sylvan-d-ash! Did you figure out what went wrong?

[sylvan-d-ash]

@MarkHao yes, I did. I should have commented about it here, because I now don't remember the problem clearly, but it had to do with the numberOfCountries being an int. I resolved it by changing it to a string.

I'm guessing that adding an encode function to deal with the int value would be another way to resolve it...but not sure about this.

[bhanuMatta]

@onmyway133 ,@sylvan-d-ash - Can you show how you created the Storage initializer function. When we are creating the Storage class init method it also asks for Transformer type.

let diskConfig = DiskConfig(
name: "GatherCache",
expiry: .date(Date().addingTimeInterval(2*86400)),
maxSize: 1000000 * 50,
directory: try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask,
appropriateFor: nil, create: true).appendingPathComponent("MyPreferences"),
protectionType: .complete
)

    let memoryConfig = MemoryConfig(
        expiry: .date(Date().addingTimeInterval(2*60)),
        countLimit: 50,
        totalCostLimit: 50
    )
    
  let storage = try? Storage(
      diskConfig: diskConfig,
      memoryConfig: memoryConfig,
      transformer: TransformerFactory.forCodable(ofType: User.self) // Storage<User>
    )

Here my User is. -
struct User : Codable {
let firstName: String
let lastName: String

enum CodingKeys: String, CodingKey {
    case firstName = "first_name"
    case lastName = "last_name"
}

}

But what i want to achieve is that , i want to cache a array of [User] . How do i do that , do I need to change my Storage init method .

[3lvis]

Hi @bhanuMatta, sorry for the late reply, where you able to resolve your issue?