MVC1001: Filters cannot be applied to page handler methods

Cause

An attribute implementing IFilterMetadata was applied to a Razor Page handler method.

Rule description

Razor Page handler methods are selected after MVC filter execution has started, and consequently cannot contribute filters to execute. Applying a filter to a Razor Page handler is unsupported and always incorrect.

public class IndexModel : PageModel
{
    [MyFilter]
    public IActionResult OnGet() => Page();
}

How to fix violations

Remove the filter from the handler and apply it to the page model. If a filter has to be applied to a specific handler, consider using multiple Razor Pages.

[MyFilter]
public class IndexModel : PageModel
{
    public IActionResult OnGet() => Page();
}

When to suppress warnings

Don't suppress warnings from this rule.