Trying to Parse JSON in C# using JSON.NET

Question

I'm trying to parse some JSON using JSON.NET but whenever I try to get the value from any of the values, it returns 0. I just want to get the values from the first set of data. Here is my code:

string text = listBox1.SelectedItem.ToString();
text = text.Substring(text.LastIndexOf(": ") + 2);
string url = "http://www.gw2spidy.com/api/v0.9/json/item-search/" + text + "/1";
var json = new WebClient().DownloadString(url);

Result itemPrices = JsonConvert.DeserializeObject<Result>(json);

int buyPrice = itemPrices.min_sale_unit_price;
int sellPrice = itemPrices.max_offer_unit_price;

sellPriceLabel.Content = "Highest Sell Price: " + sellPrice;
buyPriceLabel.Content = "Lowest Buy Price: " + buyPrice;

And here is my JSON objects class:

public class Result
{
    public int data_id { get; set; }
    public string name { get; set; }
    public int rarity { get; set; }
    public int restriction_level { get; set; }
    public string img { get; set; }
    public int type_id { get; set; }
    public int sub_type_id { get; set; }
    public string price_last_changed { get; set; }
    public int max_offer_unit_price { get; set; }
    public int min_sale_unit_price { get; set; }
    public int offer_availability { get; set; }
    public int sale_availability { get; set; }
    public int sale_price_change_last_hour { get; set; }
    public int offer_price_change_last_hour { get; set; }
}

public class RootObject
{
    public int count { get; set; }
    public int page { get; set; }
    public int last_page { get; set; }
    public int total { get; set; }
    public List<Result> results { get; set; }
}

Here is the JSON I am trying to parse:

{
"count": 3,
"page": 1,
"last_page": 1,
"total": 3,
"results": [
    {
        "data_id": 12223,
        "name": "Apple Pie",
        "rarity": 2,
        "restriction_level": 10,
        "img": "https://render.guildwars2.com/file/0A50099C343F01AC2846ADF4C8A948BA76F4DBC1/63097.png",
        "type_id": 3,
        "sub_type_id": 1,
        "price_last_changed": "2015-05-05 20:58:24 UTC",
        "max_offer_unit_price": 136,
        "min_sale_unit_price": 226,
        "offer_availability": 22161,
        "sale_availability": 4007,
        "sale_price_change_last_hour": 0,
        "offer_price_change_last_hour": 0
    },
    {
        "data_id": 12150,
        "name": "Eda's Apple Pie",
        "rarity": 1,
        "restriction_level": 5,
        "img": "https://render.guildwars2.com/file/13380176D1D569B5DD077F7DD8C412CAE9E77527/63254.png",
        "type_id": 3,
        "sub_type_id": 1,
        "price_last_changed": "2015-05-05 23:31:06 UTC",
        "max_offer_unit_price": 160,
        "min_sale_unit_price": 313,
        "offer_availability": 3596,
        "sale_availability": 2744,
        "sale_price_change_last_hour": 0,
        "offer_price_change_last_hour": 0
    },
    {
        "data_id": 9497,
        "name": "Eda's Apple Pie Recipe",
        "rarity": 1,
        "restriction_level": 0,
        "img": "https://render.guildwars2.com/file/B7B167286DD34B254E22682900C6EF2310F6EE0E/849342.png",
        "type_id": 3,
        "sub_type_id": 6,
        "price_last_changed": "2014-09-11 10:12:00 UTC",
        "max_offer_unit_price": 10101,
        "min_sale_unit_price": 0,
        "offer_availability": 0,
        "sale_availability": 0,
        "sale_price_change_last_hour": 0,
        "offer_price_change_last_hour": 0
    }
]}

Probably DeserializeObject<Result> should be DeserializeObject<RootObject> — Chris Laplante
– Chris Laplante, Commented May 6, 2015 at 2:22
When I tried your change it gives me the error "Cannot implicitly convert type 'My_Application.RootObject' to 'MyApplication.Result'" — trevj
– trevj, Commented May 6, 2015 at 2:34
You need to change the result of the line: RootObject itemPrices = JsonConvert.DeserializeObject<RootObject>(json);. And then later on you access members of Result when really you should be accessing members of RootObject. You're trying to access Results directly, but that's now how the JSON you posted is structured. — Chris Laplante
– Chris Laplante, Commented May 6, 2015 at 2:36

Peyman · Accepted Answer · 2015-05-06 02:59:13Z

1

Just changed the code as below:

var itemPrices = JsonConvert.DeserializeObject<RootObject>(json);

Also I suggest instead of create property like data_id you can use serialization attribute like this:

[DataContract(Name = "result")]
public class Result
{
   [DataMamber(Name = "data_id")]
   public int Id {get;set;}

   .........

}

Updated

Just make sure change the rest code regarding to return object. Desrialize method return RootObejct that contains list of result, so that will be impacted on rest of your code

edited May 6, 2015 at 2:59

answered May 6, 2015 at 2:24

Peyman

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4 Comments

trevj Over a year ago

When I tried your change it gives me the error "Cannot implicitly convert type 'My_Application.RootObject' to 'MyApplication.Result'"

Nguyen Kien Over a year ago

RootObject itemPrices = JsonConvert.DeserializeObject<RootObject>(json);

Peyman Over a year ago

sorry just use var itemPrice, I forgot to change that one

Shaun Luttin Over a year ago

Here is a fiddle demonstrating that this is the right answer. dotnetfiddle.net/G8TAwv

tynar · Accepted Answer · 2015-05-06 03:43:36Z

You have to parse json text as RootObject, then access Result objects through results property.

I've copied your text, appended closing braces "}" at the end and saved to file.

Everything seems to work.

using System;
using System.Collections.Generic;
using System.IO;
using Newtonsoft.Json;

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            var json = File.ReadAllText("C:\\Users\\Tynar\\Documents\\json.txt");

            RootObject itemPrices = JsonConvert.DeserializeObject<RootObject>(json);

            int buyPrice = itemPrices.results[0].min_sale_unit_price;
            int sellPrice = itemPrices.results[0].max_offer_unit_price;

            Console.WriteLine(buyPrice);
            Console.WriteLine(sellPrice);
            Console.ReadLine();
        }
    }

    public class Result
    {
        public int data_id { get; set; }
        public string name { get; set; }
        public int rarity { get; set; }
        public int restriction_level { get; set; }
        public string img { get; set; }
        public int type_id { get; set; }
        public int sub_type_id { get; set; }
        public string price_last_changed { get; set; }
        public int max_offer_unit_price { get; set; }
        public int min_sale_unit_price { get; set; }
        public int offer_availability { get; set; }
        public int sale_availability { get; set; }
        public int sale_price_change_last_hour { get; set; }
        public int offer_price_change_last_hour { get; set; }
    }

    public class RootObject
    {
        public int count { get; set; }
        public int page { get; set; }
        public int last_page { get; set; }
        public int total { get; set; }
        public List<Result> results { get; set; }
    }
}

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