Allow @page directive in Razor Components to accept constant strings

[hellfirehd]

Currently the @page directive must specify a route template. The route template must be enclosed in quotes and begin with the '/' character.

I need to be able to use a const string as well.

Is your feature request related to a problem? Please describe.

I want to define my routes in a single place and then reuse them throughout the application, eliminating as many string literals as possible. Without this, refactoring and long-term maintenance becomes a nightmare of Find/Replace.

Describe the solution you'd like

Ideal:

@page @ClientRoutes.Members.ClinicalSupervision

Acceptable:

@page "@ClientRoutes.Members.ClinicalSupervision"

public static class ClientRoutes
{
	public static class Members
	{
		public const string ClinicalSupervision = "/Members/ClinicalSupervision";
	}
}
...

private void CancelAsync() => NavigationManager.NavigateTo(ClientRoutes.Members.ClinicalSupervision);

[javiercn]

@hellfirehd thanks for contacting us.

Unfortunately, its likely not possible we can do this without significant changes into how the Razor compiler works which this issue alone might not merit the investment.

Pages use string literals because that information gets embedded in several places and is used for several checks. In addition to that, Razor lacks a semantic understanding of the C# code at compile time and it is impossible for it to resolve the constant value to perform the tasks it has to during compilation.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[denisz1]

I like example above. But anything is better than magic string, even something so simple like this:

public static class Routes
{
  public const string Route1 = "/Hello";
  public const string Route2 = "/World/Hi";
}

@page Routes.Hello

Comments written above is correct - it is HARD to maintain this system with magic string. And I find so many times debugging difficulties. With constants it will be better.

[hellfirehd]

Pages use string literals because that information gets embedded in several places and is used for several checks. In addition to that, Razor lacks a semantic understanding of the C# code at compile time and it is impossible for it to resolve the constant value to perform the tasks it has to during compilation.

Could you allow it to be set from the Code Behind?

[lonix1]

My issue was closed, as were similar ones over the years. There seems to be resistance to this, but I don't know how it can be justified. Managing something as complicated as routes with the current approach is difficult.

There are all sorts of workarounds on SO ([1], [2]) but none is perfect. It needs to be baked into the compiler/runtime.

Could you allow it to be set from the Code Behind?

That would be fine by me too, but would make assets double in size as we'd need two files for every routable component. There are some examples in those links above. And something like this would be nice too, which effectively places the compile-time constant in the generated codebehind:

@page @ROUTE
@functions { public const string ROUTE = "/Foo"; }     // can reference this const from other code

[wstaelens]

ok, what is the status of this? it was created in 2021.

[wstaelens]

• Allow Varible Parameter For Blazor @page Directive aspnetcore#28827
• @page directive: allow string constant aspnetcore#23958
• Support variable for Blazor @page directive declaration aspnetcore#25589
• Mention @attribute [Route()] As A Dynamic Alternative to @page AspNetCore.Docs#27262
• Blazor @page directive remove requirement for string double quotes (RZ1016) aspnetcore#44352
• string constant for @page directive aspnetcore#23195
• Accept @page routing and navigation with const string aspnetcore#17500
• Blazor - Support @Page static value directive aspnetcore#14098
• [Blazor] Allow to reference constant field in @page directive aspnetcore#13453
• [Feature Request] Remove magic strings from RazorPages routing aspnetcore#41930
• [Blazor] strongly defined page path and also default page path aspnetcore#41827
• ...

[lonix1]

@wstaelens Like I said above, this goes back years. There has been resistance to handling it for technical reasons (understandable...), but it's strange given how important this is. Especially given this is c# after all.