Parsing unique collection using LINQ to JSON

Question

I am trying to parse a JSON feed using LINQ and can't quite wrap a list of objects/values into a reasonable class.

My JSON looks like:

{
   "Project":[
      {
         "ID":"XY1212",
         "Name":"Some Name",
         "Description":"U.S. No 2 Diesel Retail Prices",
         "Manager":"Nora Sims",
         "Dept":"HR",
         "Updated":"2014-07-22",
         "Statistics":[
            [
               "20140722",
               32.22
            ],
            [
               "20140721",
               55
            ],
            [
               "20140720",
               343
            ],
            [
               "20140519",
               43
            ],
            [
               "20140421",
               3.971
            ],
            [
               "20140211",
               40.2
            ],
            [
               "20140210",
               17
            ],
            [
               "20140209",
               16
            ]
         ]
      }
   ]
}

From the above JSON, I have the following class structure:

public class Project
{
    public string ID { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string Manager { get; set; }
    public string Dept { get; set; }
    public string Updated { get; set; }
    public List<List<object>> Statistics { get; set; }
}

public class RootObject
{
    public List<Project> Project { get; set; }
}

public class Statistic
{
    public Datetime ProjectDate { get; set; }
    public Decimal Sale { get; set; }
}

I am trying to parse the feed and just want the "Statistics" data, but not sure how to get all of the values into the collection of "Statistics":

HttpClient() http = new HttpClient();
var json = await http.GetStringAsync(uri);

JObject jo = JObject.Parse(json);
var jList = from values in jo["Project"].Children()["Statistics"]
    select values;

When I inspect jList via the following loop:

foreach (var stat in jList)
{
    Console.WriteLine(stat);
}

I can "see" all of the values, but it only loops once, i.e. jList is only one big [0] with a "value" of all of the [x, y], [x1, y1], ..., i.e. looks like an array of one dimension with many 2D arrays inside it.

I want to loop through all of the "arrays", I believe that's what they are, within the [0] I see in Visual Studio while debugging.

Any advice appreciated.

Answer 1

You can solve this easily by making a custom JsonConverter for your Statistic class. It will deal with the unconventional JSON and allow you to define your Project class the way you'd really like to have it.

Here is the code for the converter:

class StatisticConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return (objectType == typeof(Statistic));
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        JArray array = JArray.Load(reader);
        return new Statistic
        {
            ProjectDate = DateTime.ParseExact(array[0].ToString(), "yyyyMMdd", 
                            System.Globalization.CultureInfo.InvariantCulture),
            Sale = array[1].ToObject<decimal>()
        };
    }

    public override bool CanWrite
    {
        get { return false; }
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        throw new NotImplementedException();
    }
}

To use the converter, we just need to make a couple of minor changes to your classes. First, change the Statistics property to be a List<Statistic> instead of a List<List<object>>. (Don't worry that it doesn't match the JSON-- that's what the converter is for.)

public class Project
{
    public string ID { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public string Manager { get; set; }
    public string Dept { get; set; }
    public string Updated { get; set; }
    public List<Statistic> Statistics { get; set; }
}

Next decorate your Statistic class with a [JsonConverter] attribute to tie it to the custom converter:

[JsonConverter(typeof(StatisticConverter))]
public class Statistic
{
    public DateTime ProjectDate { get; set; }
    public Decimal Sale { get; set; }
}

That's it! Now you can deserialize as normal, and you'll get a list of statistics the way you want.

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

Working demo here.

Answer 2

The problem isn't your code so much as it is the JSON string that is coming back from the HttpClient. Because it has parts that don't have a key, it is hard to sort through, also each child of statistic is a child of that child (If my eyes don't deceive me).

However, using the code below, I am able to read the Statistics values singularly

JObject jo = JObject.Parse(json);
            var jList = from values in jo["Project"]
                        select values;
            foreach (var j in jList)
            {
                var l = j["Statistics"].Children();
                foreach (var m in l.Children())
                {
                    string a = m.ToString();
                }
            }

On the first loop, m has the Date, On the second loop it has the sale. because there is no key for these, I don't know any other way to reference them.

A bit less code but similar result

JObject jo = JObject.Parse(json);
        for (int i = 0; i < jo.Count; i++)
        {
            var jList = from values in jo["Project"][i]["Statistics"]
                        select values;                
            foreach (var stat in jList)
            {
                //here stat looks like {["20140722", 32.22]}
            }

        }