Mismatch behavior between RegexRouteConstraint and produced OpenApi document

[StasPerekrestov]

When a regex-based constraint is defined,
for instance

endpoints.MapGet("/{username:alpha}", async (string username, CancellationToken cancellationToken) =>
{

AlphaRouteConstraint is applied. The constraint inherits RegexRouteConstraint which is case insensitive.
The issue is that RegexRouteConstraint.Constraint & RegexOptions.IgnoreCase isn't taken into account.

"users/{username}": {
      "get": {
        "tags": [
          "demo"
        ],
        "parameters": [
          {
            "name": "username",
            "in": "path",
            "required": true,
            "schema": {
              "pattern": "^[a-z]*$",
              "type": "string"
            }
          }
        ],

In a nutshell,
the behavior of ^[a-z]*$ is different in the OpenApi document and in AlphaRouteConstraint because the first one is case sensitive and the other one is case insensitive.

public class AlphaRouteConstraint : RegexRouteConstraint
{
    /// <summary>
    /// Initializes a new instance of the <see cref="AlphaRouteConstraint" /> class.
    /// </summary>
    public AlphaRouteConstraint() : base(@"^[a-z]*$") <--------------------
    {
    }
}

This behavior can be observed in Swagger UI when it doesn't allow to execute an HTTP request due to a failed validation:
For instance, "Jack" cannot pass the provided regex constraint.

https://swagger.io/docs/specification/data-models/data-types/
The pattern keyword lets you define a regular expression template for the string value. Only the values that match this template will be accepted. The regular expression syntax used is from JavaScript (more specifically, ECMA 262). Regular expressions are case-sensitive, that is, [a-z] and [A-Z] are different expressions.

[SDOsmany]

I am having the same issue in my .Net6 Framework app
when using the alpha constraint it becomes case sensitive

gives the following error

Please correct the following validation errors and try again. Value must follow pattern ^[a-z]*$

[Havunen]

This seems to work in DotSwashbuckle

[github-actions]

This issue is stale because it has been open for 60 days with no activity. It will be automatically closed in 14 days if no further updates are made.

[jgarciadelanoceda]

@StasPerekrestov or @SDOsmany. I have just tested using MyGet nuget and it seems to be working.
Can you please specify which version of Swashbuckle are you using?

[StasPerekrestov]

@jgarciadelanoceda
I've checked the asp.net core code and found out that the issue is fixed in .NET 8
.NET 6
.NET 7
.NET 8

I suppose the issue can be closed.
Thank you for looking into it.