Enums marked with alternate values using [EnumMember(Value="...")] are not supported

Below is copied from https://github.com/domaindrivendev/Swashbuckle/issues/562, because I am seeing the same issue in Swashbuckle.AspNetCore. It looks like someone attempted to fix this in https://github.com/domaindrivendev/Swashbuckle.AspNetCore/pull/414, but that PR is pretty out-of-date, and failing CI. That fix there appears to be replicating https://github.com/domaindrivendev/Swashbuckle/pull/563, but those changes are now out-of-date as well in Swashbuckle, as the enum schema is now generated using a Type extension.

Forgive the contrived example, but given the following code:

public class DefaultController : ApiController
{
    [ResponseType(typeof(TestResult))]
    public IHttpActionResult Get(string id)
    {
        return this.Ok(new TestResult());
    }
}

[DataContract]
public class TestResult
{
    [DataMember]
    public TestEnum Type { get; set; }
}

[DataContract]
public enum TestEnum
{
    [EnumMember(Value = "roger")]
    None = 0,
    [EnumMember(Value = "blake")]
    Something = 1,
    [EnumMember(Value = "sarah")]
    SomethingElse = 2
}

The API will return “roger”, “blake” or “sarah” depending on the enum value. Swashbuckle does not pick up on the alternative names and reports that the potential options are “None”, “Something” or “SomethingElse”.

[elize-vdr]

In case anybody needs a solution I solved it in the following way: For this enum:

    public enum AssociationMultiplicity {
        [EnumMember(Value = "unknown")]
        Unknown,
        [EnumMember(Value = "zero-or-one")]
        ZeroOrOne,
        [EnumMember(Value = "one")]
        One,
        [EnumMember(Value = "many")]
        Many
    }

Create an extension for the enumerator to convert the value to the EnumMember attribute value, here it is:

    public static class AssociationMultiplicityExtension
    {
        public static string GetEnumMember(this AssociationMultiplicity value)
        {
            var type = value.GetType();
            var name = Enum.GetName(type, value);
            if (name == null)
                return null;
            var field = type.GetField(name);
            if (field is null || !Attribute.IsDefined(field, typeof(EnumMemberAttribute)))
                return null;
            if (Attribute.GetCustomAttribute(field, typeof(EnumMemberAttribute)) is EnumMemberAttribute attr)
            {
                return attr.Value;
            }
            return null;
        }
}

Then create a SchemaFilter class like this:

public class ProblemDetailsSchemaFilter : ISchemaFilter
{
    
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {        
        if (context.Type == typeof(AssociationMultiplicity))
        {
            schema.Enum.Clear();
            var valuesArray = Enum.GetValues(typeof(AssociationMultiplicity));

            foreach (AssociationMultiplicity val in valuesArray)
            {
                schema.Enum.Add(new OpenApiString(val.GetEnumMember()));
            }

        }
    }
}

And register this SchemaFilter in the ConfigureServices where the AddSwaggerGen is called:

services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebContractsParsing API - V1", Version = "v1" });
    // For future versions an example, see here: https://github.com/domaindrivendev/Swashbuckle.AspNetCore#include-descriptions-from-xml-comments
    // c.SwaggerDoc("v2", new OpenApiInfo { Title = "WebContractsParsing API - V2", Version = "v2" });

    var filePath = Path.Combine(System.AppContext.BaseDirectory, "WebContractsParsingApi.xml");
    c.IncludeXmlComments(filePath);
    
    c.DescribeAllParametersInCamelCase();

    c.SchemaFilter<ProblemDetailsSchemaFilter>();
}

And there the EnumMember value is in the swagger UI spec

[xhafan]

@elize-vdr’s solution does not work for me for 6.3.1, but it helped me to create a solution which works for me:

public class IgnoreEnumMemberValueSchemaFilter : ISchemaFilter
{
    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
    {
        if (context.Type == typeof(AssociationMultiplicity))
        {
            schema.Enum.Clear();
            var enumValues = Enum.GetValues(typeof(AssociationMultiplicity));

            foreach (var val in enumValues)
            {
                schema.Enum.Add(new OpenApiString(GetEnumConstantNameIgnoringEnumMemberValue(val)));
            }
        }
    }

    private string GetEnumConstantNameIgnoringEnumMemberValue<TEnum>(TEnum value)
    {
        var type = value.GetType();
        return Enum.GetName(type, value);
    }
}

It basically ignores EnumMember values, and uses enum constant names as if the EnumMember attribute is missing.