Parse JSON in C#

c# asp.net json parsing json.net
Mike B picture Mike B · Jul 31, 2009 · Viewed 186.4k times · Source

I'm trying to parse some JSON data from the Google AJAX Search API. I have this URL and I'd like to break it down so that the results are displayed. I've currently written this code, but I'm pretty lost in regards of what to do next, although there are a number of examples out there with simplified JSON strings.

Being new to C# and .NET in general I've struggled to get a genuine text output for my ASP.NET page so I've been recommended to give JSON.NET a try. Could anyone point me in the right direction to just simply writing some code that'll take in JSON from the Google AJAX Search API and print it out to the screen?

EDIT: ALL FIXED! All results are working fine. Thank you again Dreas Grech!

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;

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);
        Response.Write(g1.content);
    }
}

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());
        ms.Close();
        return obj;
    }
}
/// Deserialise from JSON
[Serializable]
public class GoogleSearchResults
{
    public GoogleSearchResults() { }
    public GoogleSearchResults(string _unescapedUrl, string _url, string _visibleUrl, string _cacheUrl, string _title, string _titleNoFormatting, string _content)
    {
        this.unescapedUrl = _unescapedUrl;
        this.url = _url;
        this.visibleUrl = _visibleUrl;
        this.cacheUrl = _cacheUrl;
        this.title = _title;
        this.titleNoFormatting = _titleNoFormatting;
        this.content = _content;
    }

    string _unescapedUrl;
    string _url;
    string _visibleUrl;
    string _cacheUrl;
    string _title;
    string _titleNoFormatting;
    string _content;

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

    [DataMember]
    public string url
    {
        get { return _url; }
        set { _url = value; }
    }

    [DataMember]
    public string visibleUrl
    {
        get { return _visibleUrl; }
        set { _visibleUrl = value; }
    }
    [DataMember]
    public string cacheUrl
    {
        get { return _cacheUrl; }
        set { _cacheUrl = value; }
    }

    [DataMember]
    public string title
    {
        get { return _title; }
        set { _title = value; }
    }

    [DataMember]
    public string titleNoFormatting
    {
        get { return _titleNoFormatting; }
        set { _titleNoFormatting = value; }
    }

    [DataMember]
    public string content
    {
        get { return _content; }
        set { _content = value; }
    }
}

The code currently compiles and runs perfectly, but isn't returning any results. Could someone help me with returning what I require, the results ready to print out to the screen?

Edit:

Json.NET works using the same JSON and classes as the example above.

GoogleSearchResults g1 = JsonConvert.DeserializeObject<GoogleSearchResults>(json);

Link: Serializing and Deserializing JSON with Json.NET

Related

C# - parsing json formatted data into nested hashtables
Parse JSON array

Answer

Andreas Grech picture Andreas Grech · Aug 2, 2009

[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;}

Related questions

Convert JSON String to JSON Object c#

I have this String stored in my database: str = "{ "context_name": { "lower_bound": "value", "upper_bound": "value", "values": [ "value1", "valueN" ] } }" This string is already in the JSON format but I want to convert it into a JObject or JSON Object. …

Read More
How to create JSON string in C#

I just used the XmlWriter to create some XML to send back in an HTTP response. How would you create a JSON string. I assume you would just use a stringbuilder to build the JSON string and them format your …

Read More
How to Convert JSON object to Custom C# object?

Is there an easy way to populate my C# Object with the JSON object passed via AJAX? This is the JSON Object passed to C# WEBMETHOD from the page using JSON.stringify { "user": { "name": "asdf", "teamname": "b", "email": "c", "players": ["1", "2"] } } …

Read More