What are Routing Constraints in ASP.NET Core?

Routing Constraints in ASP.NET Core allow developers to restrict route parameters to specific types or patterns. They help ensure that only valid requests reach controller actions, improving routing accuracy and app reliability.

Key Features:

• Restrict route parameters by type, length, or regex
• Works with attribute and conventional routing
• Improves URL validation and reduces errors
• Supports custom constraints
• Enhances maintainability and clarity of routes

Example:
Attribute routing with constraints:

[Route("products/{id:int}")]
public IActionResult GetProduct(int id)
{
    return Content($"Product ID: {id}");
}

Conventional routing with constraints in Program.cs:

app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id:int?}");

Routing Constraints in ASP.NET Core ensure only valid URLs are processed, enhancing app reliability and user experience.

Citations:

• Learn more on Savanka
• Official ASP.NET Core Documentation