swift change struct model into another model if have similar id - arrays

Question

I get the response from the api as in the JSON code below
{
"timestamp": 1632838801,
"status": "ok",
"message": "ok",
"data": [
{
"id": 1,
"id_category": 6,
"products": [
{
"id": 12,
"product_name": "product one",
}
]
},
{
"id": 2,
"id_category": 6,
"products": [
{
"id": 20,
"product_name": "product two"
}
]
},
{
"id": 3,
"id_category": 13,
"products": [
{
"id": 994,
"product_name": "product three"
}
]
}
]
}
I'm success to decode the response into a struct like this:
struct ProductDataResponse {
let timestamp: Int
let status: Int
let message: String
let data: [Data]
}
struct Data {
let id: Int
let idCategory: Int
let products: [Product]
}
struct Product {
let id: Int
let productName: String
let idJelajah: Int
}
the problem is, I want my data model different from the response, if the data has the same id_cateogry then the existing product data will be grouped into the same id_category,below i attach the expected result of struct and the expected json.
the result is 2 array of diffrent id_category and product
struct ListCategory {
let idCategory
let category: [Category]
}
struct Category {
var id: Int
var product: [Product]
}
struct Product {
let id: Int
let productName: String
let idJelajah: Int
}
{
"timestamp": 1632838801,
"status": "ok",
"message": "ok",
"data": [
{
"id_category": 6,
"products": [
{
"id": 12,
"product_name": "product one",
},
{
"id": 20,
"product_name": "product two"
}
]
},
{
"id_category": 13,
"products": [
{
"id": 994,
"product_name": "product three"
}
]
},
]
}

Answer 1

With model being:
struct ProductDataResponse: Codable {
let timestamp: Double
let status: String
let message: String
let data: [Data]
struct Data: Codable {
let id: Int
let idCategory: Int
let products: [Product]
}
struct Product: Codable {
let id: Int
let productName: String
}
}
struct ProductDataOutput: Codable {
let timestamp: Double
let status: String
let message: String
let data: [Category]
struct ListCategory: Codable {
let idCategory: Int
let category: [Category]
}
struct Category: Codable {
var id: Int
var product: [Product]
}
struct Product: Codable {
let id: Int
let productName: String
}
}
Side note, to be working with your current code, I changed timestamp into a Double & status into a String, else it would cause decoding issue.
I also put them inside each other, to avoid naming. For instance, you'd need to differentiate Swift.Data & ProductDataResponse.Data, and the two Products would collide.
Also, I added a top level structure that you didn't give: ProductDataOutput.
And a helper for converting Product into Product (ie the one with structure of the response, and the one with the target one). Of course, we could use the same struct, but I wanted to separate them, just in case as you wrote it yourself.
extension ProductDataOutput.Product {
init(with otherProduct: ProductDataResponse.Product) {
self.id = otherProduct.id
self.productName = otherProduct.productName
}
}
The following code is inside a
do {
//HERE
} catch {
print("Error: \(error)")
}
That I'll skip, but keep it for debugging and catch issue.
Let's parse into the model as the Response first:
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let parsed = try decoder.decode(ProductDataResponse.self, from: Data(initialJSONStr.utf8))
print(parsed)
Then, I'd use reduce(into:_:) to group by category id the products.
let reduced = parsed.data.reduce(into: [Int: [ProductDataOutput.Product]]()) { partialResult, current in
var existing = partialResult[current.idCategory, default: []]
let newProducts = current.products.map { ProductDataOutput.Product(with: $0) }
existing.append(contentsOf: newProducts)
partialResult[current.idCategory] = existing
}
print(reduced)
Then, let's create our target structure. I used a quick map() to transform the reduced into a [ProductDataOutput.Category].
let output = ProductDataOutput(timestamp: parsed.timestamp,
status: parsed.status,
message: parsed.message,
data: reduced.map { ProductDataOutput.Category(id: $0.key, product: $0.value) })
Then, to debug the output as JSON (as it's the sample you gave):
let encoder = JSONEncoder()
encoder.keyEncodingStrategy = .convertToSnakeCase
encoder.outputFormatting = .prettyPrinted
let encodedOutput = try encoder.encode(output)
print(String(data: encodedOutput, encoding: .utf8)!)
With this, you should be fine.