246

I'm trying to deserialize a Facebook friend's Graph API call into a list of objects. The JSON object looks like:

{"data":[{"id":"518523721","name":"ftyft"},
         {"id":"527032438","name":"ftyftyf"},
         {"id":"527572047","name":"ftgft"},
         {"id":"531141884","name":"ftftft"},
         {"id":"532652067","name"...

List<EFacebook> facebooks = new JavaScriptSerializer().Deserialize<List<EFacebook>>(result);

It's not working, because the primitive object is invalid. How can I deserialize this?

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4
  • 3
    write a custom deserializer specifically to cater to such json ... Commented Oct 25, 2011 at 20:03
  • 2
    or you can use an Dictionary<string,string>,check out: stackoverflow.com/questions/7699972/… Commented Oct 25, 2011 at 20:30
  • 15
    Your friend: json2csharp.com Commented Jun 15, 2015 at 9:48
  • 7
    Actually visual studios (as of 2013, or 2012 with web tools installed) has this exact functionality built in: Edit > Paste Special > Paste JSON As Classes Commented Aug 30, 2017 at 16:00

10 Answers 10

Reset to default
296

You need to create a structure like this:

public class Friends
{

    public List<FacebookFriend> data {get; set;}
}

public class FacebookFriend
{

    public string id {get; set;}
    public string name {get; set;}
}

Then you should be able to do:

Friends facebookFriends = new JavaScriptSerializer().Deserialize<Friends>(result);

The names of my classes are just an example. You should use proper names.

Adding a sample test:

string json =
    @"{""data"":[{""id"":""518523721"",""name"":""ftyft""}, {""id"":""527032438"",""name"":""ftyftyf""}, {""id"":""527572047"",""name"":""ftgft""}, {""id"":""531141884"",""name"":""ftftft""}]}";

Friends facebookFriends = new System.Web.Script.Serialization.JavaScriptSerializer().Deserialize<Friends>(json);

foreach(var item in facebookFriends.data)
{
    Console.WriteLine("id: {0}, name: {1}", item.id, item.name);
}

Produces:

id: 518523721, name: ftyft
id: 527032438, name: ftyftyf
id: 527572047, name: ftgft
id: 531141884, name: ftftft
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5 Comments

Yeh, its what I dont want to do, create a new object to hold the childs. I think Im gonna substring the json taking out the primitive object. Thank you.
@Kevin Holditch thanks for the correction. I missed one important bit :)
What I don't like about this System.Web.Script.Serialization.JavaScriptSerializer() is that you always need a defined type T. In Java there is this org.java library (package) that remains all anonymous: "JSONObject["param"].JSONarray(5)" etc
It is important to note that the setters for the id and name properties must be left public. If they are set to private or protected, the deserialization will execute without error but all data will be null.
@sports, you can do that in C# by deserializing to a dynamic, but performance is much better if you deserialize to a known type.
59

Sometimes I prefer dynamic objects:

public JsonResult GetJson()
{
  string res;
  WebClient client = new WebClient();

  // Download string
  string value = client.DownloadString("https://api.instagram.com/v1/users/000000000/media/recent/?client_id=clientId");

  // Write values
  res = value;
  dynamic dyn = JsonConvert.DeserializeObject(res);
  var lstInstagramObjects = new List<InstagramModel>();

  foreach(var obj in dyn.data)
  {
    lstInstagramObjects.Add(new InstagramModel()
    {
      Link = (obj.link != null) ? obj.link.ToString() : "",
      VideoUrl = (obj.videos != null) ? obj.videos.standard_resolution.url.ToString() : "",
      CommentsCount = int.Parse(obj.comments.count.ToString()),
      LikesCount = int.Parse(obj.likes.count.ToString()),
      CreatedTime = new System.DateTime(1970, 1, 1, 0, 0, 0, 0).AddSeconds((double.Parse(obj.created_time.ToString()))),
      ImageUrl = (obj.images != null) ? obj.images.standard_resolution.url.ToString() : "",
      User = new InstagramModel.UserAccount()
             {
               username = obj.user.username,
               website = obj.user.website,
               profile_picture = obj.user.profile_picture,
               full_name = obj.user.full_name,
               bio = obj.user.bio,
               id = obj.user.id
             }
    });
  }

  return Json(lstInstagramObjects, JsonRequestBehavior.AllowGet);
}
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4 Comments

Once example of an instance where this was useful was when the object I was trying to deserialize into contained a property that was an interface
An explanation would be in order.
Why would you prefer this over the accepted answer by @Icarus?
@Questioning, deserialising to strong types classes would neglect any properties that were not in your classes, while deserialising to dynamic objects would just return dynamic .Net object thats flexible to any new property created in the future without the requirement to update your classes. (as I said, sometimes not standard)
51

A great way to automatically generate these classes for you is to copy your JSON output and throw it in here:

http://json2csharp.com/

It will provide you with a starting point to touch up your classes for deserialization.

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1 Comment

Another way is in VisualStudio edit>paste special>paste json as classes
34

Very easily we can parse JSON content with the help of dictionary and JavaScriptSerializer. Here is the sample code by which I parse JSON content from an ashx file.

var jss = new JavaScriptSerializer();
string json = new StreamReader(context.Request.InputStream).ReadToEnd();
Dictionary<string, string> sData = jss.Deserialize<Dictionary<string, string>>(json);
string _Name = sData["Name"].ToString();
string _Subject = sData["Subject"].ToString();
string _Email = sData["Email"].ToString();
string _Details = sData["Details"].ToString();
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2 Comments

This solution is very useful if you do not have the time or need to create data contracts. Especially if you're interested in only a few attributes buried deep in the JSON structure. In that situation you may use a series of statements to navigate to what you need. Note: the type to deserialize might also be one of the following: Dictionary<string,object> or ArrayList (when a node has a repeating structure).
I get a run time exception with this: No parameterless constructor defined for type of 'System.String' on the Deserialize line of code.
26

Newtonsoft.JSON is a good solution for these kind of situations. Also Newtonsof.JSON is faster than others, such as JavaScriptSerializer, DataContractJsonSerializer.

In this sample, you can the following:

var jsonData = JObject.Parse("your JSON data here");

Then you can cast jsonData to JArray, and you can use a for loop to get data at each iteration.

Also, I want to add something:

for (int i = 0; (JArray)jsonData["data"].Count; i++)
{
    var data = jsonData[i - 1];
}

Working with dynamic object and using Newtonsoft serialize is a good choice.

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Comments

16

I agree with Icarus (would have commented if I could), but instead of using a CustomObject class, I would use a Dictionary (in case Facebook adds something).

private class MyFacebookClass
{
    public IList<IDictionary<string, string>> data { get; set; }
}

or

private class MyFacebookClass
{
    public IList<IDictionary<string, object>> data { get; set; }
}
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1 Comment

Using dynamic works better in the new versions. public IList<IDictionary<string, dynmaic>> data { get; set; }
14

Serialization:

// Convert an object to JSON string format
string jsonData = JsonConvert.SerializeObject(obj);

Response.Write(jsonData);

Deserialization::

To deserialize a dynamic object

  string json = @"{
      'Name': 'name',
      'Description': 'des'
    }";

var res = JsonConvert.DeserializeObject< dynamic>(json);

Response.Write(res.Name);
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Comments

12

If you're using .NET Core 3.0, you can use System.Text.Json (which is now built-in) to deserialize JSON.

The first step is to create classes to model the JSON. There are many tools which can help with this, and some of the answers here list them.

Some options are http://json2csharp.com, http://app.quicktype.io, or use Visual Studio (menu Edit → Paste Special → Paste JSON as classes).

public class Person
{
    public string Id { get; set; }
    public string Name { get; set; }
}

public class Response
{
    public List<Person> Data { get; set; }
}

Then you can deserialize using:

var people = JsonSerializer.Deserialize<Response>(json);

If you need to add settings, such as camelCase handling, then pass serializer settings into the deserializer like this:

var options = new JsonSerializerOptions() { PropertyNamingPolicy = JsonNamingPolicy.CamelCase };
var person = JsonSerializer.Deserialize<Response>(json, options);
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Comments

3

You can use this extensions

public static class JsonExtensions
{
   public static T ToObject<T>(this string jsonText)
   {
       return JsonConvert.DeserializeObject<T>(jsonText);
   }

   public static string ToJson<T>(this T obj)
   {
       return JsonConvert.SerializeObject(obj);
   }
}
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Comments

2

Here is another site that will help you with all the code you need as long as you have a correctly formated JSON string available:

https://app.quicktype.io/

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Comments