Case insensitivity in enum route binding

[timgabrhel]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I am trying to use enums as a route parameter in my .net 7 minimal api, with the flexibility to have case insensitivity in the parameter binding. I've done this in .NET 6 controller based APIs which worked with identical configuration (seen below), but the behavior doesn't match here.

I am avoiding trying to write a custom parameter binding as I wish to let Swagger auto-discover the enum parameter and hydrate the enum options properly. This API spec is shared outside of my team and the documentation built in with the enums is incredibly valuable.

Expected Behavior

POST /optiona resolves the endpoint and returns the string OptionA

Steps To Reproduce

dotnet new webapi -minimal

using System.Text.Json;
using System.Text.Json.Serialization;
using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);
builder.Services.Configure<Microsoft.AspNetCore.Http.Json.JsonOptions>(o =>
{
    o.SerializerOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
    o.SerializerOptions.ReferenceHandler = ReferenceHandler.IgnoreCycles;
    o.SerializerOptions.Converters.Add(new JsonStringEnumConverter(JsonNamingPolicy.CamelCase));
});

var app = builder.Build();

app.MapGet("/", () => "Hello World!");
app.MapGet("/{myenum}", ([FromRoute] MyEnum myenum) =>
{
    return Results.Ok(myenum.ToString());
});

app.Run();

public enum MyEnum
{
    OptionA,
    OptionB
}

1. Navigate to /optiona and be shown an error

BadHttpRequestException: Failed to bind parameter "MyEnum myenum" from "optiona".

2. Navigate to /OptionA and see "OptionA" in the response body of the browser.

Exceptions (if any)

No response

.NET Version

7.0.100

Anything else?

VS Code

.NET SDK:
 Version:   7.0.100
 Commit:    e12b7af219

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  20.04
 OS Platform: Linux
 RID:         ubuntu.20.04-x64
 Base Path:   /usr/share/dotnet/sdk/7.0.100/

Host:
  Version:      7.0.0
  Architecture: x64
  Commit:       d099f075e4

.NET SDKs installed:
  7.0.100 [/usr/share/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 7.0.0 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 7.0.0 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

Other architectures found:
  None

Environment variables:
  Not set

global.json file:
  Not found

[captainsafia]

Triage: JSON options affect the way the enum is parsed if it is present in a JSON payload to the request. Since your enum is provided as a route parameter, these JSON options won't take affect.

This behavior is dictated by the logic in our parameter binding, which uses the Enum.TryParse overload that does not enable case-insensitivity.

You might want to consider implementing your own TryParse implementation on a wrapper for your MyEnum type that is case-insensitive. See more info at https://learn.microsoft.com/en-us/aspnet/core/fundamentals/minimal-apis/parameter-binding?view=aspnetcore-7.0#tryparse

[ghost]

Hi @timgabrhel. We have added the "Needs: Author Feedback" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[ghost]

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