Cannot have multiple response types for same status code

[nithinbandaru1]

I am doubtful that if this existing issue (#2413, #329) will be reopened, so here I open a new one.

OneOf is now supported by open-api standard. I believe this is a basic feature that would be useful for many.

I wonder how much trouble, the swagger docs now available in internet generated by .NET applications would be creating for consumers of those APIs. 🙂

https://spec.openapis.org/oas/v3.1.0#discriminator-object

[zleao]

This would definitely be a very nice feature to add... even if just the support for multiple schemas for same status code.
Currently don't have the availability for it, but could definitely help on the testing part, if someone would be interested on going forward with this.

[Brads3290]

Until this is implemented, I just wrote a basic operation filter that accomplishes this. Feel free to use it.

public class MultipleProducesOperationFilter : IOperationFilter {

    public void Apply(OpenApiOperation operation, OperationFilterContext context) {
        var attrs = context.MethodInfo.GetCustomAttributes(false)
            .OfType<ProducesResponseTypeAttribute>()
            .GroupBy(x => x.StatusCode)
            .Select(g => new { StatusCode = g.Key, Attributes = g.ToArray() })
            .ToList();

        var duplicateAttrs = attrs
            .Where(x => x.Attributes.Length > 1)
            .ToList();

        if (duplicateAttrs.Count == 0) {
            return;
        }

        // We have multiple attributes. Rebuild the responses.
        
        foreach (var details in duplicateAttrs) {
            var schema = BuildSchemaFromAttrs(details.Attributes, context);
            
            // I don't think there's a scenario where we would have an attribute on the method, but not
            // also have a response for the corresponding code in the dict. If that does happen, this will throw.
            var response = operation.Responses[details.StatusCode.ToString()];

            foreach (var contentType in response.Content.Keys) {
                var contentDetails = response.Content[contentType];
                contentDetails.Schema = schema;
            }
        }
    }

    private static OpenApiSchema BuildSchemaFromAttrs(IEnumerable<ProducesResponseTypeAttribute> attrs, OperationFilterContext context) {
        var schemas = new List<OpenApiSchema>();
        foreach (var attr in attrs) {
            // Expect that these will be generated as references, not inline
            var schema = context.SchemaGenerator.GenerateSchema(attr.Type, context.SchemaRepository);
            schemas.Add(schema);
        }

        return new() {
            OneOf = schemas,
        };
    }

}