Swift reusable model class/struct - swift

Question

I have a service whose response vary based on the orderNumer(input parameter which I pass to service). all most all object are same but only one object(ex meta object which is dictionary)vary based on order number. But I would like to reuse the same model class everywhere but due to different meta object can't be able to create that meta object in model class.I can achieve it by creating individual model class but not a right solution.
struct BookingInfo: Codable {
let created_time: Int
// Some other 20 key value pairs
let oms_meta: Meta /* oms_meta": {
"package": {
"description": "gzhdjjdjd"
}*/
}
// Meta for Order1
struct Meta: Codable {
let package: Description
enum CodingKeys : String, CodingKey {
case package = "package"
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
package = try values.decode(Description.self, forKey: .package)
}
}
// Meta for Order 2
struct Meta: Codable {
let customer_payment_details: Int
let items: Int // this can be anything dictinary or some time array of dictionary
enum CodingKeys : String, CodingKey {
case package = "customer_payment_details"
case items = "items"
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
customer_payment_details = try values.decode(Int.self, forKey: .package)
items = try values.decode(Int.self, forKey: .package)
}
}
Only meta parameters are varying from service to service.
Thanks in advance

Answer 1

If you want to only use 1 model, you should provide a variable for all the possible keys in the dictionary and set them as optional.
Let's say all orders have an orderNumber, but only some have an orderImage you could do it like this:
struct Order: Codable {
var orderNumber: Int
var orderImage: Data?
var orderName: String?
var orderDescription: String?
}
This way, the returned data only has to contain an orderNumber to be able to decode it.
Edit: You'd have to make a seperate model for each type of 'meta data' as they seem to be very different from eachother. Note that there is nothing wrong with creating a lot of model classes as long as they represent a specific data object.

Answer 2

[
{
"created_time": 1,
"oms_meta": {
"name": "1"
}
},
{
"created_time": 1,
"oms_meta": [
1
]
}
]
Suppose we have a response something like this, where you can have multiple oms_meta objects. So what we can do here is to specify an enum which will contain both array as well as dictionary, it doesn't matter if the service sends you array or dictionary if you need to specify other data types mentioned it in that enum. So it will be like,
struct BookingInfoElement: Codable {
let createdTime: Int?
let omsMeta: OmsMetaUnion?
enum CodingKeys: String, CodingKey {
case createdTime = "created_time"
case omsMeta = "oms_meta"
}
}
enum OmsMetaUnion: Codable {
case integerArray([Int])
case omsMetaClass(OmsMetaClass)
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
if let x = try? container.decode([Int].self) {
self = .integerArray(x)
return
}
if let x = try? container.decode(OmsMetaClass.self) {
self = .omsMetaClass(x)
return
}
throw DecodingError.typeMismatch(OmsMetaUnion.self, DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "Wrong type for OmsMetaUnion"))
}
func encode(to encoder: Encoder) throws {
var container = encoder.singleValueContainer()
switch self {
case .integerArray(let x):
try container.encode(x)
case .omsMetaClass(let x):
try container.encode(x)
}
}
}
struct OmsMetaClass: Codable {
let name: String?
enum CodingKeys: String, CodingKey {
case name = "name"
}
}
typealias BookingInfo = [BookingInfoElement]
So, if you specifically want to have multiple types for a single variable you can create another enum with that multiple types and assign accordingly. You can access that variable using switch like, and check on array and dictionary types.

Answer 3

After doing some analyses I found the solution for my requirement. As I wanted to reuse the Model class and OMS_Meta dictionary different from product to product, I'm adding omsMeta to JSONDecoder().userInfo property
struct BookingInfo: Codable {
let created_time: Int
let oms_meta: [String: Any]
}
public static let metaUserInfo = CodingUserInfoKey(rawValue: "oms_meta")!
decoder.userInfo[BookingInfo.metaUserInfo] = jsonDecode
By doing this I can re use my model class.