Parse Json with multiple objects newtonsoft

Question

I'm attempting to parse a rather convoluted/unnecessarily complicated JSON output using newtonsoft in C# however for some reason my parser always returns null and doesn't elaborate as to exactly why this is the case.

An example of a JSON file I'm trying to parse:

   {
    "response": {
        "success": 1,
        "current_time": 1362339098,
        "prices": {
            "35": { 
                "11": { 
                    "0": { 
                        "current": {
                            "currency": "keys",
                            "value": 39,
                            "value_high": 41,
                            "date": 1357515306 
                        },
                        "previous": { 
                            "currency": "keys",
                            "value": 37,
                            "value_high": 39
                        }
                    }
                },
                "3": { 
                    "0": { 
                        "current": {
                            "currency": "metal",
                            "value": 0.33,
                            "value_high": 0.66
                        }
                    }
                }
            },
            "5002": { 
                "6": {
                    "0": {
                        "current": {
                            "currency": "usd",
                            "value": 0.39,
                            "value_high": 0.42,
                            "date": 1358090106
                        }
                    }
                }
            },                          
            "5022": {
                "6": {
                    "1": { 
                        "current": {
                            "currency": "metal",
                            "value": 1.33,
                            "value_high": 1.55,
                            "date": 1357515175
                        }
                    }
                }
            }
        }
    }
}

And the C# parser I'm using. I run the getCurrentPrices() to return a PriceParser object but instead the object returned is always null.

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

namespace SteamBot
{
    class PriceParser
    {
        //Methods
        public PriceParser updatePrices()
        {
            var json = File.ReadAllText("test.json");
            ParserResult result = JsonConvert.DeserializeObject<ParserResult>(json);
            return result.result;
        }

        public Data currentPrices { get; set; }

        //DATA
        public class Data
        {
            public Response Response { get; set; }
        }

        public class Response 
        {
           public string success { get; set; }
           public string current_time {get; set;}
          public List<Price> prices { get; set;}
        }

        public class Price
        {
            public int defindex { get; set; }
            public int quality { get; set; }
            public Current current { get; set; }
            public Previous previous { get; set; }
        }

        public class Current
        {
            public string currency { get; set; }
            public float value { get; set; }
            public float value_high { get; set; }
            public int date { get; set; }
        }

        public class Previous
        {
            public string currency { get; set; }
            public float value { get; set; }
            public float value_high { get; set; }
            public int date { get; set; }
        }

        protected class ParserResult
        {
            public PriceParser result { get; set; }
        }
    }
}

I'm probably just missing something stupid but for the life of me I can't figure out what, anyone with more JSON wrangling experience know what's going on here?

I have edited your title. Please see, "Should questions include “tags” in their titles?", where the consensus is "no, they should not". — John Saunders
– John Saunders, Commented Nov 6, 2013 at 3:30

Brian Rogers · Accepted Answer · 2013-11-06 06:10:25Z

You are getting null values because your class structure does not match your JSON.

The first issue is that you are deserializing into a ParserResult when you should be using a Data. Data has a response property, matching your JSON. ParserResult does not have this property.

The second issue is that you have defined prices to be a List<Price>, but your JSON does not contain an array. Instead, the JSON structure is actually a series of nested dictionaries.

Try defining your inner classes like this:

public class Data
{
    public Response response { get; set; }
}

public class Response
{
    public int success { get; set; }
    public long current_time { get; set; }
    public IDictionary<int, IDictionary<int, IDictionary<int, Price>>> prices { get; set; }
}

public class Price
{
    public Quote current { get; set; }
    public Quote previous { get; set; }
}

public class Quote
{
    public string currency { get; set; }
    public decimal value { get; set; }
    public decimal value_high { get; set; }
    public long date { get; set; }
}

Then, in your updatePrices method you can deserialize like this:

public PriceParser updatePrices()
{
    var json = File.ReadAllText("test.json");
    currentPrices = JsonConvert.DeserializeObject<Data>(json);
    return this;
}

Here is how you would dump out the data:

PriceParser parser = new PriceParser();
parser.updatePrices();

foreach (var defindex in parser.currentPrices.response.prices)
{
    Console.WriteLine("defindex: " + defindex.Key);
    foreach (var quality in defindex.Value)
    {
        Console.WriteLine("\t quality: " + quality.Key);
        foreach (var price in quality.Value)
        {
            Console.WriteLine("\t\t index: " + price.Key);
            Console.WriteLine("\t\t\t current price:");
            Console.WriteLine("\t\t\t\t currency: " + price.Value.current.currency);
            Console.WriteLine("\t\t\t\t value: " + price.Value.current.value);
            Console.WriteLine("\t\t\t\t value_high: " + price.Value.current.value_high);
            if (price.Value.previous != null)
            {
                Console.WriteLine();
                Console.WriteLine("\t\t\t previous price:");
                Console.WriteLine("\t\t\t\t currency: " + price.Value.previous.currency);
                Console.WriteLine("\t\t\t\t value: " + price.Value.previous.value);
                Console.WriteLine("\t\t\t\t value_high: " + price.Value.previous.value_high);
            }
        }
    }
}

And here is the output of the above:

defindex: 35
         quality: 3
                 index: 0
                         current price:
                                 currency: metal
                                 value: 0.33
                                 value_high: 0.66
         quality: 11
                 index: 0
                         current price:
                                 currency: keys
                                 value: 39
                                 value_high: 41

                         previous price:
                                 currency: keys
                                 value: 37
                                 value_high: 39
defindex: 5002
         quality: 6
                 index: 0
                         current price:
                                 currency: usd
                                 value: 0.39
                                 value_high: 0.42
defindex: 5022
         quality: 6
                 index: 1
                         current price:
                                 currency: metal
                                 value: 1.33
                                 value_high: 1.55

This works wonderfully, the nested dictionaries make me dizzy but I guess that more a function of the way the JSON is output than anything I have control over.
Yes it does seem like a strange format for an API. Depending on your needs you could do some post-processing after deserializing to flatten it down to a more digestible form.

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