Serialize/Deserialize System.Drawing.Color with System.Text.Json

Question

The problem was to serialize/deserialize a class with Color from System.Drawing.Color with System.Text.Json.

public class Test
{
    public Color Farbe { get; set; }
    public IEnumerable<Color> Farben { get; set; }
}

Serialization

File.WriteAllText("data.json", JsonSerializer.Serialize(test));

without any converters the serialized json file looks like this:

{
  "Farbe": {
    "R": 255,
    "G": 0,
    "B": 0,
    "A": 255,
    "...": "...",
    "Name":" Red"
  },
  "Farben": [
    {
      "R":255,
      "G":0,
      "B":0,
      "A":255,
      "...": "...",
      "Name":"Red"
    },
    {
      "R":0,
      "G":128,
      "B":0,
      "A":255,
      "...": "...",
      "Name":"Green"
    }
  ]
}

Deserialisation is not possible. The result will be empty:

Test test2 = JsonSerializer.Deserialize<Test>(File.ReadAllText("data.json"));

Console.WriteLine($"{test2.Farbe.R}:{test2.Farbe.G}:{test2.Farbe.B}");
Console.WriteLine(string.Join(',', test2.Farben));

Result

0:0:0
Color [Empty],Color [Empty],Color [Empty]

This isn't a particularly useful Q&A really. You're trying to serialise a class that was never intended to be serialised in the first place. — DavidG, Oct 21 '21 at 15:43
@DavidG - I'd have to disagree with that. `System.Drawing.Color` has a typeconverter specifically so it can be persisted. See also [Serializer for Drawing.Color using Json.NET](https://stackoverflow.com/q/35246672) or [JSON.NET serialization of System.Drawing.Color with TypeNameHandling](https://stackoverflow.com/q/27584530) or [Most elegant XML serialization of Color structure](https://stackoverflow.com/q/3280362) for other questions about serializing colors -- there's clearly a demand for this. — dbc, Nov 01 '21 at 17:08

sunriax · Accepted Answer · 2021-11-06T05:14:21.477

After some searching i found a solution and get a converter for System.Drawing.Color:

public class ColorJsonConverter : JsonConverter<Color>
{
    public override Color Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options) => ColorTranslator.FromHtml(reader.GetString());

    public override void Write(Utf8JsonWriter writer, Color value, JsonSerializerOptions options) => writer.WriteStringValue("#" + value.R.ToString("X2") + value.G.ToString("X2") + value.B.ToString("X2").ToLower());
}

With the converter, serialization/deserilization is working proper.

Test test = new()
{
    Farbe = Color.Red,
    Farben = new List<Color>()
    {
        Color.Red,
        Color.Green,
        Color.Blue
    }
};

var options = new JsonSerializerOptions()
{
    Converters = {
        new ColorJsonConverter()
    }
};

File.WriteAllText("data.json", JsonSerializer.Serialize(test, options));

Test test2 = JsonSerializer.Deserialize<Test>(File.ReadAllText("data.json"), options);

Console.WriteLine($"{test2.Farbe.R}:{test2.Farbe.G}:{test2.Farbe.B}");
Console.WriteLine(string.Join(',', test2.Farben));

Result

255:0:0
Color [A=255, R=255, G=0, B=0],Color [A=255, R=0, G=128, B=0],Color [A=255, R=0, G=0, B=255]

Thank you! Very helpful, was experiencing a problem with FileInfo, DirectoryInfo. I couldn't find a good example. — user1529413, Nov 26 '21 at 00:01

Serialize/Deserialize System.Drawing.Color with System.Text.Json

1 Answers1