Code produced by CSharpGenerator for enums does not work with System.Text.Json

[virovets64]

Hello! I'm trying to use CSharpGenerator to generate C# code from JSON schema. The schema contains enums with camelStyle members. But when I serialize the generated classes with System.Text.Json, the resulting JSON contains PascalStyle enums, which violates the schema.

To reproduce

Schema example:

{
  "$schema": "http://json-schema.org/schema#",
  "type": "object",
  "properties": {
    "starType": {
      "type": "string",
      "enum": [ "redGiant", "whiteDwarf" ]
    }
  }
}

I run the generator in the following way:

string code = new CSharpGenerator(schema, new CSharpGeneratorSettings
{
  JsonLibrary = CSharpJsonLibrary.SystemTextJson,
  Namespace = "Example"
}).GenerateFile("Star");

Here is the code generated:

//----------------------
// <auto-generated>
//     Generated using the NJsonSchema v10.4.4.0 (Newtonsoft.Json v9.0.0.0) (http://NJsonSchema.org)
// </auto-generated>
//----------------------

namespace Example
{
    #pragma warning disable // Disable all warnings

    [System.CodeDom.Compiler.GeneratedCode("NJsonSchema", "10.4.4.0 (Newtonsoft.Json v9.0.0.0)")]
    public partial class Star 
    {
        [System.Text.Json.Serialization.JsonPropertyName("starType")]
        [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter))]
        public StarType StarType { get; set; }
    
        private System.Collections.Generic.IDictionary<string, object> _additionalProperties = new System.Collections.Generic.Dictionary<string, object>();
    
        [System.Text.Json.Serialization.JsonExtensionData]
        public System.Collections.Generic.IDictionary<string, object> AdditionalProperties
        {
            get { return _additionalProperties; }
            set { _additionalProperties = value; }
        }
    
    
    }
    
    [System.CodeDom.Compiler.GeneratedCode("NJsonSchema", "10.4.4.0 (Newtonsoft.Json v9.0.0.0)")]
    public enum StarType
    {
        [System.Runtime.Serialization.EnumMember(Value = @"redGiant")]
        RedGiant = 0,
    
        [System.Runtime.Serialization.EnumMember(Value = @"whiteDwarf")]
        WhiteDwarf = 1,
    
    }
}

Then I serialize the generated class:

static void Main(string[] args)
{
  var star = new Example.Star()
  {
    StarType = Example.StarType.RedGiant
  };
  string serialized = JsonSerializer.Serialize(star);
  Console.WriteLine(serialized);
}

The resulting JSON is

{
  "starType": "RedGiant"
}

Adding JsonStringEnumConverter has no effect:

string serialized = JsonSerializer.Serialize(star, new JsonSerializerOptions
{
  Converters =
  {
    new JsonStringEnumConverter(JsonNamingPolicy.CamelCase)
  }
});

Suggestions

1. System.Runtime.Serialization.EnumMember attribute is ignored by System.Text.Json, see https://github.com/dotnet/runtime/issues/31081
2. System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter)) attribute generated for StarType property overloads my JsonStringEnumConverter specified in JsonSerializerOptions.

I tried to find a workaround but failed.

Best regards, Mikhail Virovets

[eholman]

I'm having the exact issue where the EnumMemberAttribute value is not read. I also have a custom converter available, added to the JsonSerializerOptions of the generated client.

Currently I'm digging through the code of NJsonSchema. At this moment I think it should become optional to get the converter attribues generated in C#, regardless jsonLibrary setting - at this moment the option is not there.

{%   if property.IsStringEnum -%}
{%     if UseSystemTextJson -%}
    [System.Text.Json.Serialization.JsonConverter(typeof(System.Text.Json.Serialization.JsonStringEnumConverter))]
{%     else -%}
    [Newtonsoft.Json.JsonConverter(typeof(Newtonsoft.Json.Converters.StringEnumConverter))]
{%     endif -%}
{%   endif -%}

[jochenjonc]

I agree with @eholman, it should be optional to have the JsonConverter attribute added or not. And if possible to use the JsonStringEnumMemberConvertor from the Macross.Json.Extensions or other custom one.