How to decode nested JSON array and object with JSONDecoder in swift 4.1 and xcode 9.3?

Question

I am new to iOS and I am having trouble decoding a nested JSON file which has many nested arrays and objects. I am using JSONDecoder to decode, but somewhere I am making a mistake or not decoding correctly.

my decoder is

let myOrder = try JSONDecoder().decode(MyOrder.self, from: data!)
                    for items in myOrder.OrderDetials {
                        self.orders.append(MyOrders(order_id: items.order_id!, order_ref_number: items.order_ref_number!, cust_mob: items.cust_mob!, store_name: items.store_name!, store_id: items.store_id!, order_details: items.order_details!, order_amount: items.order_amount!, order_status: items.order_status!, order_status_remark: items.order_status_remark!, order_place_at: items.order_place_at!, order_status_change_at: items.order_status_change_at!))
                        print(items.cust_mob!)
                    }
                    print(myOrder)

The error its throwing is

typeMismatch(Swift.Array<Any>, Swift.DecodingError.Context(codingPath: [CodingKeys(stringValue: "OrderDetials", intValue: nil), _JSONKey(stringValue: "Index 0", intValue: 0), CodingKeys(stringValue: "order_details", intValue: nil)], debugDescription: "Expected to decode Array<Any> but found a string/data instead.", underlyingError: nil))

my structures are

struct MyOrder: Decodable {
    var OrderDetials: [OrderDetails]
}

struct OrderDetails: Decodable {
    var order_id: String?
    var order_ref_number: String?
    var cust_mob: String?
    var store_name: String?
    var store_id: String?
    var order_details: OrderItems?
    var order_amount: String?
    var order_status: String?
    var order_status_remark: String?
    var order_place_at: String?
    var order_status_change_at: String?

}

struct OrderItems: Decodable {
    var allorder: [AllOrder]
    var TaxDetials: [TaxDetails]


    struct AllOrder: Decodable {
        var date_time: String?
        var item: String?
        var name: String?
    }
    struct TaxDetails: Decodable {
        var tax_per: String?
        var tax_name: String?
    }

}

and DataModel class

class MyOrders {
    var order_id: String
    var order_ref_number: String
    var cust_mob: String
    var store_name: String
    var store_id: String
    var order_details: OrderItems?
    var order_amount: String
    var order_status: String
    var order_status_remark: String
    var order_place_at: String
    var order_status_change_at: String?

    init(order_id: String, order_ref_number: String, cust_mob: String, store_name: String, store_id: String, order_details: OrderItems?, order_amount: String, order_status: String, order_status_remark: String, order_place_at: String, order_status_change_at: String?) {
        self.order_id = order_id
        self.order_ref_number = order_ref_number
        self.cust_mob = cust_mob
        self.store_name = store_name
        self.store_id = store_id
        self.order_details = order_details
        self.order_amount = order_amount
        self.order_status = order_status
        self.order_status_remark = order_status_remark
        self.order_place_at = order_place_at
        self.order_status_change_at = order_status_change_at
    }
}

class MyItems {
    var item: String
    var name: String
    var price: String

    init(item: String, name: String, price: String) {
        self.item = item
        self.name = name
        self.price = price
    }
}

my JSON is

{
    "OrderDetials": [
        {
            "order_id": "11",
            "order_ref_number": "MM1525235813",
            "cust_mob": "9958324531",
            "store_name": "Moti mahal",
            "store_id": "1",
            "order_details": "{'allorder':[{\"date_time\":\"\",\"item\":\"2\",\"name\":\"CHICKN ROLL\",\"price\":\"360\"}]}{\"TaxDetials\":[{\"tax_per\":\"5\",\"tax_name\":\"CGST & SGST\"}]}",
            "order_amount": "378.0",
            "order_status": "1",
            "order_status_remark": "New_Order_Place",
            "order_place_at": "2018-05-02 10:06:53",
            "order_status_change_at": null
        }
    ]
}

please someone tell me how to decode it correctly or what changes I need to do in structures.

Your value for "order_details" key is string and your struct is treating it as Array.You have to change value of "order_details" key according to your defined struct to make it work — Vikky
– Vikky, Commented May 17, 2018 at 5:33
your order_details contains the structure like JSON not string — PPL
– PPL, Commented May 17, 2018 at 5:39
I tried doing this: "var order_details: String?" and this: "var order_details: [OrderItems]?" both are giving same errors. @Vikky — Neck
– Neck, Commented May 17, 2018 at 5:45
Checkout this article, it explains really well medium.com/@nimjea/json-parsing-in-swift-2498099b78f — subin272
– subin272, Commented Sep 24, 2018 at 10:00

Abdelahad Darwish · Accepted Answer · 2018-05-17 07:59:49Z

3

OrderDetials is Array of Dictionary [[String: String?]] , and your Initial response is Dictionary also order_details is Wrong json String not Dictionary , so we will parse it as string , in Codable every dictionary {} is converted t Struct or Class and [] is Array

Model:

import Foundation

struct Initial: Codable {
    let orderDetials: [OrderDetial]

    enum CodingKeys: String, CodingKey {
        case orderDetials = "OrderDetials"
    }
}

struct OrderDetial: Codable {
    let orderID, orderRefNumber, custMob, storeName: String
    let storeID, orderDetails, orderAmount, orderStatus: String
    let orderStatusRemark, orderPlaceAt: String
    let orderStatusShangeAt:String?

    enum CodingKeys: String, CodingKey {
        case orderID = "order_id"
        case orderRefNumber = "order_ref_number"
        case custMob = "cust_mob"
        case storeName = "store_name"
        case storeID = "store_id"
        case orderDetails = "order_details"
        case orderAmount = "order_amount"
        case orderStatus = "order_status"
        case orderStatusRemark = "order_status_remark"
        case orderPlaceAt = "order_place_at"
        case orderStatusShangeAt = "order_status_change_at"


    }
}


// MARK: Convenience initializers

extension Initial {
    init(data: Data) throws {
        self = try JSONDecoder().decode(Initial.self, from: data)
    }
}

Used Like this :

   if  let initial =  try? Initial.init(data: data){

                for item in initial.orderDetials {
                    print(item.orderAmount)
                    print(item.orderDetails) // here is Wrong format from your Server API
                }
           }

Order_details is wrong

{'allorder':[{"date_time":"","item":"2","name":"CHICKN ROLL","price":"360"}]}{"TaxDetials":[{"tax_per":"5","tax_name":"CGST & SGST"}]}

answered May 17, 2018 at 7:59

Abdelahad Darwish

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5 Comments

Neck Over a year ago

Now I got orderDetails as String. Do I need to use JSONSerialization to access data inside it or JSONDecoder will automatically do that?

Abdelahad Darwish Over a year ago

yes you cnan parse it again but it also wrong check this 'allorder' not "allorder"

Neck Over a year ago

Thanks, actually the JSON is generated by API team and also android team is using the same JSON and it's working there, So I have to use the same JSON.

Neck Over a year ago

No, it's same as on server. I have double checked.

Abdelahad Darwish Over a year ago

ok so your backend developer is wrong you can check with your android developer may be he format this string with any other way , but this wrong Json and wrong json string

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