C#•15mo ago

❔ Cannot deserialize System.Drawing.Color from JSON

It seems like the System.Text.Json library is not able to deserialize a Color from a JSON string it serialized before. Code I used for testing:

public static void TestSerialisation()
{
    Color toJson = Color.FromArgb(0xFF, 0xF, 0x36);
    string inJson = JsonSerializer.Serialize(toJson);
    Color fromJson = JsonSerializer.Deserialize<Color>(inJson);
}

public static void TestSerialisation()
{
    Color toJson = Color.FromArgb(0xFF, 0xF, 0x36);
    string inJson = JsonSerializer.Serialize(toJson);
    Color fromJson = JsonSerializer.Deserialize<Color>(inJson);
}

75 Replies

Pobiega•15mo ago

Write your own converter then

ero•15mo ago

tuple issue i guess whoopie

Pobiega•15mo ago

Yup, seems likely

ConnerOP•15mo ago

I dont think I understand?

Pobiega•15mo ago

Tuples can be serialized but not easily deserialized. You will need a custom converter afaik

ConnerOP•15mo ago

but the Color struct doesnt use Tuples

Thinker•15mo ago

What Color struct is this? From System.Drawing?

ConnerOP•15mo ago

yes

Thinker•15mo ago

ah, seems like it's read-only yeah you'd probably need to write your own STJ converter for it

Thinker•15mo ago

https://learn.microsoft.com/en-us/dotnet/standard/serialization/system-text-json/converters-how-to?pivots=dotnet-7-0

How to write custom converters for JSON serialization - .NET

Learn how to create custom converters for the JSON serialization classes that are provided in the System.Text.Json namespace.

ConnerOP•15mo ago

ah ok I get it then. I was just confused because the Newtonsoft.Json library was able to do it when I still used that

TheRanger•15mo ago

tbh serializing the other properties are unnecessarily

Thinker•15mo ago

idk how Newtonsoft would be able to do that since the properties are get-only

ConnerOP•15mo ago

What if I create my own color struct and add an implicit cast to System.Drawing.Color

TheRanger•15mo ago

maybe newtonsoft had a custom converter for Color

MODiX•15mo ago

ero

REPL Result: Success

System.Text.Json.JsonSerializer.Serialize((1, 2, 3, 4))

System.Text.Json.JsonSerializer.Serialize((1, 2, 3, 4))

Result: string

{}

{}

Quoted by

<@542772576905199626> from #bot-spam (click here)

Compile: 549.845ms | Execution: 48.130ms | React with ❌ to remove this embed.

ero•15mo ago

Thinker•15mo ago

what's the deal with tuples? System.Drawing.Color isn't a tuple

ero•15mo ago

ARGB is

ero•15mo ago

Thinker•15mo ago

no it's not that's just how it displays it looks like a debugger display attribute if you look at the code, they're clearly serializing toJson, which is a Color

Pobiega•15mo ago

Iirc it uses reflection to get the private setter

Thinker•15mo ago

ero•15mo ago

there is no setter actually it's a readonly struct it also has no public constructor except for the default parameterless one i guess

ConnerOP•15mo ago

Ill just go ahead an write a custom converter prevents it from saving all the unnecessary fields as well

TheRanger•15mo ago

u could try this

MODiX•15mo ago

TheRanger

REPL Result: Success

using System.Drawing;
using System.Text.Json;
public class ColorSerializer
{
    struct col
    {
        public byte R{get;set;}
        public byte G{get;set;}
        public byte B{get;set;}
        public byte A{get;set;}
    }
    public static string Serialize(Color color)
    {
        var foo = new col{R=color.R,G=color.G,B=color.B,A=color.A};
        return JsonSerializer.Serialize(foo);
    }
    
    public static Color Deserialize(string str)
    {
        var foo = JsonSerializer.Deserialize<col>(str);
        return Color.FromArgb(foo.A, foo.R, foo.G, foo.B);
    }
}

        Color toJson = Color.FromArgb(0xFF, 0xF, 0x36);
        string inJson = ColorSerializer.Serialize(toJson);
        Color fromJson = ColorSerializer.Deserialize(inJson);
        Console.WriteLine(fromJson);

using System.Drawing;
using System.Text.Json;
public class ColorSerializer
{
    struct col
    {
        public byte R{get;set;}
        public byte G{get;set;}
        public byte B{get;set;}
        public byte A{get;set;}
    }
    public static string Serialize(Color color)
    {
        var foo = new col{R=color.R,G=color.G,B=color.B,A=color.A};
        return JsonSerializer.Serialize(foo);
    }
    
    public static Color Deserialize(string str)
    {
        var foo = JsonSerializer.Deserialize<col>(str);
        return Color.FromArgb(foo.A, foo.R, foo.G, foo.B);
    }
}

        Color toJson = Color.FromArgb(0xFF, 0xF, 0x36);
        string inJson = ColorSerializer.Serialize(toJson);
        Color fromJson = ColorSerializer.Deserialize(inJson);
        Console.WriteLine(fromJson);

Console Output

Color [A=255, R=255, G=15, B=54]

Color [A=255, R=255, G=15, B=54]

Compile: 811.230ms | Execution: 124.396ms | React with ❌ to remove this embed.

ConnerOP•15mo ago

Thanks but I dont want to only serialize one color. I have a bunch of dictionaries with dictionaries with colors in them

TheRanger•15mo ago

u mean a color array/list?

ConnerOP•15mo ago

No I mean dictionaries with more dictionaries and then colors in those

TheRanger•15mo ago

i see, then ud probably need a custom converter then

ConnerOP•15mo ago

So I am having trouble writing this converter I would like my colors to be converted to the following "FieldName" : "R, G, B" Obviously for writing I could just do

public override void Write(Utf8JsonWriter writer, Color value, JsonSerializerOptions options)
{
    writer.WriteStringValue($"{value.R}, {value.G}, {value.B}");
}

public override void Write(Utf8JsonWriter writer, Color value, JsonSerializerOptions options)
{
    writer.WriteStringValue($"{value.R}, {value.G}, {value.B}");
}

but I am not sure how the reader would work with this

TheRanger•15mo ago

read the docs u can define a method called Read

ConnerOP•15mo ago

yes I know I dont know how to properly extract the values though would I have to just call ReadString and then do some string manipulation there? Because obviously its all in one string

TheRanger•15mo ago

you can use .Split, or regex

ConnerOP•15mo ago

Jimmacle•15mo ago

i'm late but the contents of "fromJson" aren't valid json to begin with looks like it just .ToString()ed the color

ConnerOP•15mo ago

what fromJson isnt even a string

Jimmacle•15mo ago

ignore me i can't read

TheRanger•15mo ago

theyre writing the converter now

Jimmacle•15mo ago

too many variables called json when

ConnerOP•15mo ago

happens to the best of us

reflectronic•15mo ago

internal sealed class ColorJsonConverter : JsonConverter<Color>
{
    private static ColorConverter converter = new();

    public override Color Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        return (Color)converter.ConvertFromString(reader.GetString() ?? "")!;
    }

    public override void Write(Utf8JsonWriter writer, Color value, JsonSerializerOptions options)
    {
        writer.WriteStringValue(converter.ConvertToString(value));
    }
}

internal sealed class ColorJsonConverter : JsonConverter<Color>
{
    private static ColorConverter converter = new();

    public override Color Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
    {
        return (Color)converter.ConvertFromString(reader.GetString() ?? "")!;
    }

    public override void Write(Utf8JsonWriter writer, Color value, JsonSerializerOptions options)
    {
        writer.WriteStringValue(converter.ConvertToString(value));
    }
}

this is what you want

TheRanger•15mo ago

it allocates more data tho theres a space after each when

ConnerOP•15mo ago

does ConvertFromString work if the colors are seperated by commas opposed to semicolons?

reflectronic•15mo ago

yes that is how it serializes by default as well well. ColorConverter does some special stuff. consider:

ConnerOP•15mo ago

it does not work with commas it seems, unfortunate

MODiX•15mo ago

reflectronic

REPL Result: Success

using System.Drawing;
var converter = new ColorConverter();
new
{
    NoAlpha = converter.ConvertToString(Color.FromArgb(100, 80, 60)),
    WithAlpha = converter.ConvertToString(Color.FromArgb(50, 100, 80, 60)),
    WellKnown = converter.ConvertToString(Color.CornflowerBlue),
    System = converter.ConvertToString(SystemColors.MenuHighlight)
}

using System.Drawing;
var converter = new ColorConverter();
new
{
    NoAlpha = converter.ConvertToString(Color.FromArgb(100, 80, 60)),
    WithAlpha = converter.ConvertToString(Color.FromArgb(50, 100, 80, 60)),
    WellKnown = converter.ConvertToString(Color.CornflowerBlue),
    System = converter.ConvertToString(SystemColors.MenuHighlight)
}

Result: <>f__AnonymousType0#1<string, string, string, string>

{
  "noAlpha": "100, 80, 60",
  "withAlpha": "50, 100, 80, 60",
  "wellKnown": "CornflowerBlue",
  "system": "MenuHighlight"
}

{
  "noAlpha": "100, 80, 60",
  "withAlpha": "50, 100, 80, 60",
  "wellKnown": "CornflowerBlue",
  "system": "MenuHighlight"
}

Compile: 520.415ms | Execution: 74.759ms | React with ❌ to remove this embed.

MODiX•15mo ago

reflectronic

REPL Result: Success

using System.Drawing;
var converter = new ColorConverter();
converter.ConvertFromString("50,80,120")

using System.Drawing;
var converter = new ColorConverter();
converter.ConvertFromString("50,80,120")

Result: Color

{
  "r": 50,
  "g": 80,
  "b": 120,
  "a": 255,
  "isKnownColor": false,
  "isEmpty": false,
  "isNamedColor": false,
  "isSystemColor": false,
  "name": "ff325078"
}

{
  "r": 50,
  "g": 80,
  "b": 120,
  "a": 255,
  "isKnownColor": false,
  "isEmpty": false,
  "isNamedColor": false,
  "isSystemColor": false,
  "name": "ff325078"
}

Compile: 563.665ms | Execution: 36.646ms | React with ❌ to remove this embed.

ConnerOP•15mo ago

huh

reflectronic•15mo ago

what do you mean by it not working

ConnerOP•15mo ago

Im not sure either now

ConnerOP•15mo ago

I get this exception

ConnerOP•15mo ago

but this might be due to a bad json file? ill check

reflectronic•15mo ago

oh, i see what the problem is

ConnerOP•15mo ago

no defnitely doesnt work with commas in the json

reflectronic•15mo ago

use ConvertToString(null, CultureInfo.InvariantCulture, value)

TheRanger•15mo ago

huh it works here

reflectronic•15mo ago

yeah it uses the list separator based on the current culture

TheRanger•15mo ago

oh their culture

reflectronic•15mo ago

oh, actuall

TheRanger•15mo ago

but wait shouldnt converter.ConvertToString(value) return 255. 255. 255?

reflectronic•15mo ago

you can just use (Color)converter.ConvertFromInvariantString(reader.GetString() ?? "") and converter.ConvertToInvariantString(color)

TheRanger•15mo ago

or whatever the list seperator their culture uses

reflectronic•15mo ago

it would but i imagine this JSON was serialized before

TheRanger•15mo ago

or maybe they used an already serialized json when

ConnerOP•15mo ago

whats this whole culture thing like is it due to me living in a different country I have different list seperators?

reflectronic•15mo ago

yes

ConnerOP•15mo ago

what a stupid feature

TheRanger•15mo ago

based on ur pc settings its not some cultures uses . as the default seperator

reflectronic•15mo ago

it is actually much more stupid to show someone that lives in Germany 27.5 instead of 27,5 in their user interface

ConnerOP•15mo ago

it is, I wouldnt mind having to use semicolons but if people in other countries share their files they would be incompatible I guess

reflectronic•15mo ago

that is why you use ConvertFromInvariantString like i said it fixes this issue

ConnerOP•15mo ago

Yea I get it. I just didnt expect list seperators to be different in other cultures I thought there would be some standard to it Yea thanks I will try that

Accord•15mo ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ Cannot deserialize System.Drawing.Color from JSON