C# deserialize JSON problem with missing attribute

Question

I have a problem to deserialize a json object by using javascriptserialize method with sometimes missing attribute. I'm new in C# deserailize here is the json ouptut:

{"result": [{"id": "1", "inc_group": {"link": "XXX","value": "222"}},{"id": "2","inc_group": ""},{"id": "3","inc_group": {"link": "YYY","value": "654"}}] }

the attribute inc_group can be empty sometimes. Here is my sample script:

public class inc_group
{
    public string link { get; set; }
    public string value { get; set; }

}

public class Result
{
    public string id { get; set; }
    public inc_group inc_group { get; set; }
 }

public class Root
{
    public List<Result> result { get; set; }

}

 using (WebResponse response = request.GetResponse())
    {
        Stream responseStream = response.GetResponseStream();
        using (StreamReader reader = new StreamReader(responseStream, Encoding.UTF8))
        {
            string json = reader.ReadToEnd();
            var json_Dictionary = js.Deserialize<Root>(json);

Here is the error message: extract JSON [2]: System.InvalidOperationException: Impossible to convert an object type 'System.String' to 'ScriptMain+Inc_Group'

this error appears when it deserializes the json

thanks in advance for your help

Answer 1

You can try with below class

public class Result
{
    public string id { get; set; }
    public object inc_group { get; set; }
}

public class Root
{
    public List<Result> result { get; set; }
}


Root items = JsonConvert.DeserializeObject<Root>(json);

Using JavaScript Deserialization

JavaScriptSerializer js = new JavaScriptSerializer();  
Root items = js.Deserialize<Root>(json);  

I have tried with above class and its parsing Json and converting to C# object without any error.

Parsing data will be done as below if you are using JavaScriptSerializer

foreach (var item in items.result)
{
    dynamic obj = item.inc_group;
    if (obj is string)
    {
         string strValue = obj;
    }
    else
    {
         foreach (KeyValuePair<string, object> kvp in obj)
         {
              Console.WriteLine("Key = {0}, Value = {1}",
                     kvp.Key, kvp.Value);
         }
     }
}

If you are using NewtonSoft JsonConvert.Deserialize method then it will be something like this.

foreach (var item in items.result)
{
   dynamic obj = item.inc_group;
   if (obj is string)
   {
       string strValue = obj;
   }
   else
   {
       string link = obj.link;
       string value = obj.value;
   }
}

Answer 2

In your Result definition, put public inc_group? inc_group public inc_group? inc_group to show that that field is nullable , and thus doesn't always have to contain a value, and the deserialisation should work.

Also set set JsonSerializerOptions.IgnoreNullValues setting to true.