JSON.NET Deserialize objects within object / array of objects

Question

I have a situation where an API I'm using is returning inconsistent JSON, which I want to deserialize using JSON.NET. In one case, it returns an object that contains objects (note that the outer "1" can be any number):

{
   "1":{
      "0":{
         "db_id":"12835424",
         "title":"XXX"
      },
      "1":{
         "db_id":"12768978",
         "title":"YYY"
      },
      "2":{
         "db_id":"12768980",
         "title":"ZZZ"
      },
      "3":{
         "db_id":"12768981",
         "title":"PPP"
      }
   }
}

And in another case, it returns an array of objects:

{
   "3":[
      {
         "db_id":"12769199",
         "title":"XXX"
      },
      {
         "db_id":"12769200",
         "title":"YYY"
      },
      {
         "db_id":"12769202",
         "title":"ZZZ"
      },
      {
         "db_id":"12769243",
         "title":"PPP"
      }
   ]
}

I have no idea why this inconsistency exists, but this is the format I'm working with. What would be the correct way to deserialize both formats with the JsonConvert.DeserializeObject method?

Jami · Accepted Answer · 2013-01-13 08:09:29Z

With the current version of Json.NET (Json.NET 4.5 Release 11), here is a CustomCreationConverter that will handle Json that deserializes sometimes as an object and sometimes as an array.

public class ObjectToArrayConverter<T> : CustomCreationConverter<List<T>> where T : new() 
{
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        List<T> target = new List<T>();

        try
        {
            // Load JObject from stream
            JArray jArray = JArray.Load(reader);

            // Populate the object properties
            serializer.Populate(jArray.CreateReader(), target);
        }
        catch (JsonReaderException)
        {
            // Handle case when object is not an array...

            // Load JObject from stream
            JObject jObject = JObject.Load(reader);

            // Create target object based on JObject
            T t = new T();

            // Populate the object properties
            serializer.Populate(jObject.CreateReader(), t);

            target.Add(t);
        }

        return target;
    }

    public override List<T> Create(Type objectType)
    {
        return new List<T>();
    }
}

Example Usage:

[JsonObject]
public class Project
{
    [JsonProperty]
    public string id { get; set; }

    // The Json for this property sometimes comes in as an array of task objects, 
    // and sometimes it is just a single task object.
    [JsonProperty]
    [JsonConverter(typeof(ObjectToArrayConverter<Task>))]
    public List<Task> tasks{ get; set; }
}

[JsonObject]
public class Task
{
    [JsonProperty]
    public string name { get; set; }

    [JsonProperty]
    public DateTime due { get; set; }
}

This should be the accepted answer. Precise and fully functional plug and play. Thanks.

Mark Monster · Accepted Answer · 2012-06-04 09:35:17Z

2

I think this is something that should be possible by creating a JsonCreationConverter. This article can probably help out: http://dotnetbyexample.blogspot.nl/2012/02/json-deserialization-with-jsonnet-class.html

answered Jun 4, 2012 at 9:35

Mark Monster

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