How do I Serialize object to json using json.net which contains an image property

Question

I have an object with a number of public properties where one is of type image. I am trying to serialise this using json.net and assume that I will need to base64 encode th

Answer 1

Json.NET has no idea about what is Image, so you have to help it a bit, for example by using a converter (BinaryConverter is not for images):

public class ImageConverter : JsonConverter
{
    public override object ReadJson(JsonReader reader, Type objectType, object existingValue, JsonSerializer serializer) {
        var base64 = (string)reader.Value;
        // convert base64 to byte array, put that into memory stream and feed to image
        return Image.FromStream(new MemoryStream(Convert.FromBase64String(base64)));
    }

    public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer) {
        var image = (Image) value;
        // save to memory stream in original format
        var ms = new MemoryStream();
        image.Save(ms, image.RawFormat);
        byte[] imageBytes = ms.ToArray();
        // write byte array, will be converted to base64 by JSON.NET
        writer.WriteValue(imageBytes);
    }

    public override bool CanConvert(Type objectType) {
        return objectType == typeof(Image);
    }
}

public class Person
{
    public string name { get; set; }

    public int age { get; set; }

    [JsonConverter(typeof(ImageConverter))]
    public Image photo { get; set; }

    public string ToJson()
    {
        return JsonConvert.SerializeObject(this);
    }
}

Then it will both serialize and deserialize your class just fine.

Answer 2

I would recommend in this case to convert the image to base64 and then serialize it, here an example of how to do it in C#: Convert Image to Base64