Exclude specific Enum values from Swagger

Question

I always add an Uninitialized value to all my enums and set it to 0 to handle cases where I deserialize an object that has an enum property value that was never set.

enum MyEnum
{
    Uninitialized = 0,
    MyEnumValue1 = 1,
    MyEnumValue2 = 2,
    MyEnumValue3 = 3,
}

However, I don't want the Uninitialized value to show up in my Swagger documentation.

I've tried adding the [JsonIgnore] attribute to that value, but that didn't work.

Anyone know how to accomplish this?

Answer 1

Just in case anyone else struggles with this. You can create a custom SchemaFilter and populate the Enum property filtering on those enum values with a custom attribute (in this example: OpenApiIgnoreEnumAttribute).

    public class OpenApiIgnoreEnumSchemaFilter : ISchemaFilter
    {
        public void Apply(OpenApiSchema schema, SchemaFilterContext context)
        {
            if (context.Type.IsEnum)
            {
                var enumOpenApiStrings = new List<IOpenApiAny>();

                foreach (var enumValue in Enum.GetValues(context.Type))
                {
                    var member = context.Type.GetMember(enumValue.ToString())[0];
                    if (!member.GetCustomAttributes<OpenApiIgnoreEnumAttribute>().Any())
                    {
                        enumOpenApiStrings.Add(new OpenApiString(enumValue.ToString()));
                    }
                }

                schema.Enum = enumOpenApiStrings;
            }
        }
    }

    public class OpenApiIgnoreEnumAttribute : Attribute
    {
    }

    public enum ApplicationRole
    {
        [OpenApiIgnoreEnum]        
        DoNotExpose = 1,        
        ValueA = 2,        
        ValueB = 3,
    }