Parse JSON in C#

Question

[Update]
I've just realized why you weren't receiving results back... you have a missing line in your Deserialize method. You were forgetting to assign the results to your obj :

public static T Deserialize<T>(string json)
{
    using (MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
    {
        DataContractJsonSerializer serializer = new DataContractJsonSerializer(typeof(T));
        return (T)serializer.ReadObject(ms);
    } 
}

Also, just for reference, here is the Serialize method :

public static string Serialize<T>(T obj)
{
    DataContractJsonSerializer serializer = new DataContractJsonSerializer(obj.GetType());
    using (MemoryStream ms = new MemoryStream())
    {
        serializer.WriteObject(ms, obj);
        return Encoding.Default.GetString(ms.ToArray());
    }
}

---

Edit

If you want to use Json.NET here are the equivalent Serialize/Deserialize methods to the code above..

Deserialize:

JsonConvert.DeserializeObject<T>(string json);

Serialize:

JsonConvert.SerializeObject(object o);

This are already part of Json.NET so you can just call them on the JsonConvert class.

Link: Serializing and Deserializing JSON with Json.NET

---

Now, the reason you're getting a StackOverflow is because of your Properties.

Take for example this one :

[DataMember]
public string unescapedUrl
{
    get { return unescapedUrl; } // <= this line is causing a Stack Overflow
    set { this.unescapedUrl = value; }
}

Notice that in the getter, you are returning the actual property (ie the property's getter is calling itself over and over again), and thus you are creating an infinite recursion.

---

Properties (in 2.0) should be defined like such :

string _unescapedUrl; // <= private field

[DataMember]
public string unescapedUrl
{
    get { return _unescapedUrl; } 
    set { _unescapedUrl = value; }
}

You have a private field and then you return the value of that field in the getter, and set the value of that field in the setter.

---

Btw, if you're using the 3.5 Framework, you can just do this and avoid the backing fields, and let the compiler take care of that :

public string unescapedUrl { get; set;}

Your data class doesn't match the JSON object. Use this instead:

[DataContract]
public class GoogleSearchResults
{
    [DataMember]
    public ResponseData responseData { get; set; }
}

[DataContract]
public class ResponseData
{
    [DataMember]
    public IEnumerable<Results> results { get; set; }
}

[DataContract]
public class Results
{
    [DataMember]
    public string unescapedUrl { get; set; }

    [DataMember]
    public string url { get; set; }

    [DataMember]
    public string visibleUrl { get; set; }

    [DataMember]
    public string cacheUrl { get; set; }

    [DataMember]
    public string title { get; set; }

    [DataMember]
    public string titleNoFormatting { get; set; }

    [DataMember]
    public string content { get; set; }
}

Also, you don't have to instantiate the class to get its type for deserialization:

public static T Deserialise<T>(string json)
{
    using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
    {
        var serialiser = new DataContractJsonSerializer(typeof(T));
        return (T)serialiser.ReadObject(ms);
    }
}

I found this approach which parse JSON into a dynamic object, it extends a DynamicObject and JavascriptConverter to turn the string into an object.

DynamicJsonObject

public class DynamicJsonObject : DynamicObject
{
    private IDictionary<string, object> Dictionary { get; set; }

    public DynamicJsonObject(IDictionary<string, object> dictionary)
    {
        this.Dictionary = dictionary;
    }

    public override bool TryGetMember(GetMemberBinder binder, out object result)
    {
        result = this.Dictionary[binder.Name];

        if (result is IDictionary<string, object>)
        {
            result = new DynamicJsonObject(result as IDictionary<string, object>);
        }
        else if (result is ArrayList && (result as ArrayList) is IDictionary<string, object>)
        {
            result = new List<DynamicJsonObject>((result as ArrayList).ToArray().Select(x => new DynamicJsonObject(x as IDictionary<string, object>)));
        }
        else if (result is ArrayList)
        {
            result = new List<object>((result as ArrayList).ToArray());
        }

        return this.Dictionary.ContainsKey(binder.Name);
    }
}

Converter

public class DynamicJsonConverter : JavaScriptConverter
{
    public override object Deserialize(IDictionary<string, object> dictionary, Type type, JavaScriptSerializer serializer)
    {
        if (dictionary == null)
            throw new ArgumentNullException("dictionary");

        if (type == typeof(object))
        {
            return new DynamicJsonObject(dictionary);
        }

        return null;
    }

    public override IDictionary<string, object> Serialize(object obj, JavaScriptSerializer serializer)
    {
        throw new NotImplementedException();
    }

    public override IEnumerable<Type> SupportedTypes
    {
        get { return new ReadOnlyCollection<Type>(new List<Type>(new Type[] { typeof(object) })); }
    }
}

Usage (sample json):

JavaScriptSerializer jss = new JavaScriptSerializer();
jss.RegisterConverters(new JavaScriptConverter[] { new DynamicJsonConverter() });

dynamic glossaryEntry = jss.Deserialize(json, typeof(object)) as dynamic;

Console.WriteLine("glossaryEntry.glossary.title: " + glossaryEntry.glossary.title);
Console.WriteLine("glossaryEntry.glossary.GlossDiv.title: " + glossaryEntry.glossary.GlossDiv.title);
Console.WriteLine("glossaryEntry.glossary.GlossDiv.GlossList.GlossEntry.ID: " + glossaryEntry.glossary.GlossDiv.GlossList.GlossEntry.ID);
Console.WriteLine("glossaryEntry.glossary.GlossDiv.GlossList.GlossEntry.GlossDef.para: " + glossaryEntry.glossary.GlossDiv.GlossList.GlossEntry.GlossDef.para);
foreach (var also in glossaryEntry.glossary.GlossDiv.GlossList.GlossEntry.GlossDef.GlossSeeAlso)
{
    Console.WriteLine("glossaryEntry.glossary.GlossDiv.GlossList.GlossEntry.GlossDef.GlossSeeAlso: " + also);
}

This method has to return true, otherwise it will throw an error. E.g. you can throw an error if a key does not exist.

Returning true and emptying result will return an empty value rather than throwing an error.

public override bool TryGetMember(GetMemberBinder binder, out object result)
{

    if (!this.Dictionary.ContainsKey(binder.Name))
    {
        result = "";
    }
    else
    {
        result = this.Dictionary[binder.Name];
    }

    if (result is IDictionary<string, object>)
    {
        result = new DynamicJsonObject(result as IDictionary<string, object>);
    }
    else if (result is ArrayList && (result as ArrayList) is IDictionary<string, object>)
    {
        result = new List<DynamicJsonObject>((result as ArrayList).ToArray().Select(x => new DynamicJsonObject(x as IDictionary<string, object>)));
    }
    else if (result is ArrayList)
    {
        result = new List<object>((result as ArrayList).ToArray());
    }

    return true; // this.Dictionary.ContainsKey(binder.Name);
}

I just think the whole example would be useful. This is the example for this problem.

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.ServiceModel.Web;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.IO;
using System.Text;
using System.Collections.Generic;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        GoogleSearchResults g1 = new GoogleSearchResults();
        const string json = @"{""responseData"": {""results"":[{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://www.cheese.com/"",""url"":""http://www.cheese.com/"",""visibleUrl"":""www.cheese.com"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:bkg1gwNt8u4J:www.cheese.com"",""title"":""\u003cb\u003eCHEESE\u003c/b\u003e.COM - All about \u003cb\u003echeese\u003c/b\u003e!."",""titleNoFormatting"":""CHEESE.COM - All about cheese!."",""content"":""\u003cb\u003eCheese\u003c/b\u003e - everything you want to know about it. Search \u003cb\u003echeese\u003c/b\u003e by name, by types   of milk, by textures and by countries.""},{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://en.wikipedia.org/wiki/Cheese"",""url"":""http://en.wikipedia.org/wiki/Cheese"",""visibleUrl"":""en.wikipedia.org"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:n9icdgMlCXIJ:en.wikipedia.org"",""title"":""\u003cb\u003eCheese\u003c/b\u003e - Wikipedia, the free encyclopedia"",""titleNoFormatting"":""Cheese - Wikipedia, the free encyclopedia"",""content"":""\u003cb\u003eCheese\u003c/b\u003e is a food consisting of proteins and fat from milk, usually the milk of   cows, buffalo, goats, or sheep. It is produced by coagulation of the milk \u003cb\u003e...\u003c/b\u003e""},{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://www.ilovecheese.com/"",""url"":""http://www.ilovecheese.com/"",""visibleUrl"":""www.ilovecheese.com"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:GBhRR8ytMhQJ:www.ilovecheese.com"",""title"":""I Love \u003cb\u003eCheese\u003c/b\u003e!, Homepage"",""titleNoFormatting"":""I Love Cheese!, Homepage"",""content"":""The American Dairy Association\u0026#39;s official site includes recipes and information   on nutrition and storage of \u003cb\u003echeese\u003c/b\u003e.""},{""GsearchResultClass"":""GwebSearch"",""unescapedUrl"":""http://www.gnome.org/projects/cheese/"",""url"":""http://www.gnome.org/projects/cheese/"",""visibleUrl"":""www.gnome.org"",""cacheUrl"":""http://www.google.com/search?q\u003dcache:jvfWnVcSFeQJ:www.gnome.org"",""title"":""\u003cb\u003eCheese\u003c/b\u003e"",""titleNoFormatting"":""Cheese"",""content"":""\u003cb\u003eCheese\u003c/b\u003e uses your webcam to take photos and videos, applies fancy special effects   and lets you share the fun with others. It was written as part of Google\u0026#39;s \u003cb\u003e...\u003c/b\u003e""}],""cursor"":{""pages"":[{""start"":""0"",""label"":1},{""start"":""4"",""label"":2},{""start"":""8"",""label"":3},{""start"":""12"",""label"":4},{""start"":""16"",""label"":5},{""start"":""20"",""label"":6},{""start"":""24"",""label"":7},{""start"":""28"",""label"":8}],""estimatedResultCount"":""14400000"",""currentPageIndex"":0,""moreResultsUrl"":""http://www.google.com/search?oe\u003dutf8\u0026ie\u003dutf8\u0026source\u003duds\u0026start\u003d0\u0026hl\u003den-GB\u0026q\u003dcheese""}}, ""responseDetails"": null, ""responseStatus"": 200}";
        g1 = JSONHelper.Deserialise<GoogleSearchResults>(json);

        foreach (Pages x in g1.responseData.cursor.pages)
        {
            // Anything you want to get
            Response.Write(x.label);

        }
    }
}

public class JSONHelper
{
    public static T Deserialise<T>(string json)
    {
        using (var ms = new MemoryStream(Encoding.Unicode.GetBytes(json)))
        {
            var serialiser = new DataContractJsonSerializer(typeof(T));
            return (T)serialiser.ReadObject(ms);
        }
    }

    public static string Serialize<T>(T obj)
    {
        DataContractJsonSerializer serializer = new DataContractJsonSerializer(obj.GetType());
        using (MemoryStream ms = new MemoryStream())
        {
            serializer.WriteObject(ms, obj);
            return Encoding.Default.GetString(ms.ToArray());
        }
    }
}

[DataContract]
public class GoogleSearchResults
{
    [DataMember]
    public ResponseData responseData { get; set; }

    [DataMember]
    public string responseStatus { get; set; }

}


public class ResponseData
{
    [DataMember]
    public Cursor cursor { get; set; }

    [DataMember]
    public IEnumerable<Results> results { get; set; }


}


[DataContract]
public class Cursor
{
    [DataMember]
    public IEnumerable<Pages> pages { get; set; }
}



[DataContract]
public class Pages
{
    [DataMember]
    public string start { get; set; }

    [DataMember]
    public string label { get; set; }

}


[DataContract]
public class Results
{
    [DataMember]
    public string unescapedUrl { get; set; }

    [DataMember]
    public string url { get; set; }

    [DataMember]
    public string visibleUrl { get; set; }

    [DataMember]
    public string cacheUrl { get; set; }

    [DataMember]
    public string title { get; set; }

    [DataMember]
    public string titleNoFormatting { get; set; }

    [DataMember]
    public string content { get; set; }
}

I tried to use the code above but didn't work. The JSON structure returned by Google is so different and there is a very important miss in the helper function: a call to DataContractJsonSerializer.ReadObject() that actually deserializes the JSON data into the object.

Here is the code that WORKS in 2011:

using System;
using System.Runtime.Serialization;
using System.Runtime.Serialization.Json;
using System.IO;
using System.Text;
using System.Collections.Generic;

namespace <YOUR_NAMESPACE>
{
    public class JSONHelper
    {
        public static T Deserialise<T>(string json)
        {
            T obj = Activator.CreateInstance<T>();
            MemoryStream ms = new MemoryStream(Encoding.Unicode.GetBytes(json));
            DataContractJsonSerializer serialiser = new DataContractJsonSerializer(obj.GetType());
            obj = (T)serialiser.ReadObject(ms);
            ms.Close();
            return obj;
        }
    }

    public class Result
    {
        public string GsearchResultClass { get; set; }
        public string unescapedUrl { get; set; }
        public string url { get; set; }
        public string visibleUrl { get; set; }
        public string cacheUrl { get; set; }
        public string title { get; set; }
        public string titleNoFormatting { get; set; }
        public string content { get; set; }
    }

    public class Page
    {
        public string start { get; set; }
        public int label { get; set; }
    }

    public class Cursor
    {
        public string resultCount { get; set; }
        public Page[] pages { get; set; }
        public string estimatedResultCount { get; set; }
        public int currentPageIndex { get; set; }
        public string moreResultsUrl { get; set; }
        public string searchResultTime { get; set; }
    }

    public class ResponseData
    {
        public Result[] results { get; set; }
        public Cursor cursor { get; set; }
    }

    public class GoogleSearchResults
    {
        public ResponseData responseData { get; set; }
        public object responseDetails { get; set; }
        public int responseStatus { get; set; }
    }
}

To get the content of the first result, do:

GoogleSearchResults googleResults = new GoogleSearchResults();
googleResults = JSONHelper.Deserialise<GoogleSearchResults>(jsonData);
string contentOfFirstResult = googleResults.responseData.results[0].content;