SlugifyParameterTransformer would not work well if specifying route attribute with curly braces {controller}/{action}

[FredHan001]

In section about "Token replacement in route templates [controller], [action], [area]", we can find enclosing a token in curly braces would also be supported, like below.

[Route("{controller}/{action}")]
public IActionResult SomeTestPage()
{
    return Ok("success");
}

It would cause that SlugifyParameterTransformer functionality not work. Using [Route("[controller]/[action]")] on action method, which would work well. I'd like to know why this happens. Thanks.

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Document Details

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• ID: 8ee6ad2f-1667-8d5c-1f36-9d0511e3720f
• Version Independent ID: 7838ccec-c8e8-9baa-2b3e-220b2af5fc58
• Content: Routing to controller actions in ASP.NET Core
• Content Source: aspnetcore/mvc/controllers/routing.md
• Product: aspnet-core
• Technology: aspnetcore-mvc
• GitHub Login: @Rick-Anderson
• Microsoft Alias: riande

[Rick-Anderson]

Hello! Thanks for contacting us. This sounds like a general question about using ASP.NET Core. While we try to look at and respond to all issues, for questions like this we recommend posting to a community support group like Stack Overflow with the asp.net-core tag.

• Stack Overflow
• ASP.NET Core Slack
• ASP.NET Gitter

Potential bugs in the ASP.NET Core framework and product feedback can be reported at dotnet/aspnetcore issues (include full repro steps and cross-link to a repro project in GH when appropriate). For Visual Studio, use the Report a Problem gesture or Suggest a Feature gesture within VS, which open internal issues for the VS team. For Visual Studio Code, you can open an issue at microsoft/vscode issues.

[FredHan001]

Hi Rick, thanks for your response. Not sure if it is a potential bug. But if ASP.NET Core developers follow this doc and use curly braces with these token(s) like [Route("{controller}/{action}")] to achieve SlugifyParameterTransformer functionality (this section about "Use a parameter transformer to customize token replacement" also included in same doc), which would not work well. So it will confuse us why doc told curly braces is supported but not working well with SlugifyParameterTransformer scenario.

For convenience, attribute routes support token replacement for reserved route parameters by enclosing a token in one of the following:

• Square brackets: []
• Curly braces: {}

[Rick-Anderson]

cc @serpent5

[serpent5]

The implementation shows that an IOutboundParameterTransformer processes only [ and ] when used with attribute routing. I don't know if that is intentional, but it's unusual to see route templates use e.g. {controller} instead of [controller].

[noctis0430]

When learning ASP.NET Core, developers tend to use consistent syntax. New developers (like myself) was introduced to use curly bracket when learning conventional routing. So I suppose it is normal that new developers tends to use curly bracket as well when comes to attribute routing (even though square bracket is also a viable option) for consistency.

Is it possible to make the use of square bracket and/or curly bracket consistent across both conventional and attribute routing?

[serpent5]

@Rick-Anderson How do you want to proceed with this?

I suggest we update the section to only mention using [] and perhaps redirect the product question/request over to the engineering repo.

[Rick-Anderson]

Agreed.