webapi中的自定义路由约束
Custom Route Constraints
You can create custom route constraints by implementing the IHttpRouteConstraint interface. For example, the following constraint restricts a parameter to a non-zero integer value.
public class NonZeroConstraint : IHttpRouteConstraint
{
public bool Match(HttpRequestMessage request, IHttpRoute route, string parameterName,
IDictionary<string, object> values, HttpRouteDirection routeDirection)
{
object value;
if (values.TryGetValue(parameterName, out value) && value != null)
{
long longValue;
if (value is long)
{
longValue = (long)value;
return longValue != 0;
}
string valueString = Convert.ToString(value, CultureInfo.InvariantCulture);
if (Int64.TryParse(valueString, NumberStyles.Integer,
CultureInfo.InvariantCulture, out longValue))
{
return longValue != 0;
}
}
return false;
}
}
The following code shows how to register the constraint:
public static class WebApiConfig
{
public static void Register(HttpConfiguration config)
{
var constraintResolver = new DefaultInlineConstraintResolver();
constraintResolver.ConstraintMap.Add("nonzero", typeof(NonZeroConstraint));
config.MapHttpAttributeRoutes(constraintResolver);
}
}
Now you can apply the constraint in your routes:
[Route("{id:nonzero}")]
public HttpResponseMessage GetNonZero(int id) { ... }
You can also replace the entire DefaultInlineConstraintResolver class by implementing the IInlineConstraintResolver interface. Doing so will replace all of the built-in constraints, unless your implementation of IInlineConstraintResolver specifically adds them.