Creating lowercase routes in ASP.NET Web API

When it comes to creating lowercase routes in ASP.NET Web API, there is no built-in facility to automatically lowercase all of your routes as is the case with ASP.NET MVC.

However, you can still solve this issue without resorting to Attribute-based routing and manually writing all of your routes in lowercase.

This can be accomplished through Custom Route Constraints.  In this instance, you will want to create a Custom Route Constraint which simply translates all of the default ASP.NET Web API routes into their corresponding lowercase version.

You can write a LowercaseRouteConstraint as follows:

	public class RouteConfig
	{
	public static void RegisterRoutes(RouteCollection routes)
	{
	routes.MapHttpRoute(
	name: "DefaultApi",
	routeTemplate: "api/{controller}/{id}",
	defaults: new { id = RouteParameter.Optional },
	constraints: new { url = new LowercaseRouteConstraint() }
	);
	}
	}
	public class LowercaseRouteConstraint : IRouteConstraint
	{
	public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
	{
	var path = httpContext.Request.Url.AbsolutePath;
	return path.Equals(path.ToLowerInvariant(), StringComparison.InvariantCulture);
	}
	}

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