ASP.NET Core MVC Interview Question #77

What are route constraints in ASP.NET Core MVC?

Advanced Routing, Filters, Areas & Application Structure Mid-Level Intermediate

Quick Interview Answer

Route constraints restrict which values can match a route parameter. Common constraints include int, guid, bool, datetime, length, min, max, and regex-based constraints.

Detailed Explanation

Route constraints restrict which values can match a route parameter. Common constraints include int, guid, bool, datetime, length, min, max, and regex-based constraints.

Constraints are useful for disambiguating similar routes and preventing an endpoint from matching values that clearly do not fit its route shape. They are primarily a routing-selection mechanism, not a replacement for input validation.

Code Example

[HttpGet("products/{id:int:min(1)}")]
public IActionResult Details(int id)
{
    return View();
}