Deserializing Json from a stream into a string property

Question

In order to reuse an existing code that uses Newtonsoft Json.NET I need to be able to deserialize the whole json content of a stream into a single property of a "BadData" object.

Example:

public class BadDataEntity
{
  [Key]
  public int ID { get; set; }

  public string BadData { get; set; }
}

Is there a combination of attributes I can add to this class so when I deserialize any Json it goes completley as a string into the BadData property?

Thanks.

So in other words, you don't really want to deserialize the JSON at all. If that's the case, you don't need Json.NET. Just get the contents of the stream as a string and set the property on the object. — Brian Rogers, Dec 30 '15 at 23:28
I have a code that deserializes messages from a queue into entities and persist the entities. It will be ideal if I could, using configuration only, use the same process to point to the deadletter queue, use a different entity (BadRecords) and persist the full Json without having to write a separate service. — wndproc, Dec 31 '15 at 14:06

score 0 · Answer 1 · answered Jan 01 '16 at 01:00

If for whatever reason you must parse this class using Json.NET (rather than simply reading the stream into a string then manually constructing your class from it), you can create a custom JsonConverter that loads the JSON into a JToken then stores its string value into your BadDataEntity class:

public class BadDataEntityConverter : JsonConverter
{
    public override bool CanConvert(Type objectType)
    {
        return typeof(BadDataEntity).IsAssignableFrom(objectType);
    }

    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer)
    {
        // Note that BadData MUST BE VALID JSON, otherwise this won't work.
        var token = JToken.Load(reader);
        var bad = (existingValue as BadDataEntity ?? new BadDataEntity());
        bad.BadData = JsonConvert.SerializeObject(token, Formatting.Indented);
        return bad;
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
    {
        var bad = (BadDataEntity)value;
        if (bad.BadData == null)
            writer.WriteNull();
        else
        {
            var token = JToken.Parse(bad.BadData);
            token.WriteTo(writer, serializer.Converters.ToArray());
        }
    }
}

Note that the string must contain valid JSON.

Then you can attach the converter to your class like so:

[JsonConverter(typeof(BadDataEntityConverter))]
public class BadDataEntity
{
    [Key]
    public int ID { get; set; }

    public string BadData { get; set; }
}

Or put it in the list of converters, as is shown in the documentation and in this question.

Deserializing Json from a stream into a string property

1 Answers1