How to correctly parse JSON with root element as an array in Swift 4?

Question

I have the following response from an API:

[
    {
        "stores": [
            {
                "store": {
                    "Name": "A store name",
                    "City": "NY"
                }
            },
            {
                "store": {
                    "Name": "A second store name",
                    "City": "ny2"
                }
            }
        ]
    }, 

    {

        "products": [
            {
                "product": {
                    "name": "a product",
                    "price": "1"
                }
            },
            {
                "product": {
                    "name": "a second product",
                    "price": "2"
                }
            }
        ]

    }

]

For the two JSON objects (stores and products) I've created the following structures:

struct shops_response: Codable {

    var stores: [stores]
}

struct products_response: Codable {

    var products: [products]
}


struct stores: Codable {
    var store: store
}

struct store: Codable {
    var Name:String
    var City:String
}

struct products: Codable {
    var product: product
}

struct product: Codable {

    var name:String
    var price:String

}

Using this code from below I've successfully parsed the response (where APIresponse.json is the json received from the API - I'm using it for testing purposes only):

let path = Bundle.main.path(forResource: "APIresponse", ofType: "json")
let url = URL(fileURLWithPath: path!)

let data = try! Data(contentsOf:url)

let jsonArray = try! JSONSerialization.jsonObject(with: data, options: []) as? [[String:Any]]
let storesJsonData = try! JSONSerialization.data(withJSONObject: jsonArray![0], options: .prettyPrinted)
let productsJsonData = try! JSONSerialization.data(withJSONObject: jsonArray![1], options: .prettyPrinted)


let stores = try! JSONDecoder().decode(shops_response.self, from: storesJsonData)
let products = try! JSONDecoder().decode(products_response.self, from: productsJsonData)

My question is: Is there another cleaner/easier way to parse this type of json in Swift 4 ?

That's a very inconvenient JSON. Are you responsible for it? An array stores containing dictionaries each containing only one(!) dictionary with key store is cumbersome and actually redundant. — vadian
– vadian, Commented Feb 3, 2018 at 10:43
@vadian No... It's a JSON response from an API that I have to work with. Indeed the JSON it's quite difficult. The only solution that I've found is the one I've presented in the question. — Madalin
– Madalin, Commented Feb 3, 2018 at 10:49
I'd ask the owner of the service to consider sending a more suitable format. 😉 — vadian
– vadian, Commented Feb 3, 2018 at 10:51

Gereon · Accepted Answer · 2018-02-03 11:12:26Z

6

This is really an awkwardly structured JSON. If you can't get the sender to change the format, here's my attempt at parsing it using JSONDecoder:

typealias Response = [Entry]

struct Entry: Codable {
    let stores: [StoreEntry]?
    let products: [ProductEntry]?
}

struct ProductEntry: Codable {
    let product: Product
}

struct Product: Codable {
    let name, price: String
}

struct StoreEntry: Codable {
    let store: Store
}

struct Store: Codable {
    let name, city: String

    enum CodingKeys: String, CodingKey {
        case name = "Name"
        case city = "City"
    }
}

let response = try JSONDecoder().decode(Response.self, from: data)
let stores = response.flatMap { $0.stores.map { $0.map { $0.store } } }.flatMap { $0 }
let products = response.flatMap { $0.products.map { $0.map { $0.product } } }.flatMap { $0 }

edited Feb 3, 2018 at 11:12

answered Feb 3, 2018 at 10:52

Gereon

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