CODEWITHSUNDEEP
asp.netasp.net-mvcregexasp.net-mvc-3asp.net-mvc-routing
tugberk
tugberk

Reputation: 58494

ASP.NET MVC 3 Route Constraint : Regular Expression for not null

I am trying to create a route constraint but not sure what would be the best for this. Here is the route with no constraint : 

context.MapRoute(
    "Accommodation_accomm_tags",
    "accomm/{controller}/{action}/{tag}",
    new { action = "Tags", controller = "AccommProperty" },
    new { tag = @"" } //Here I would like to put a RegEx for not null match
);

What would be the best solution for this?

Upvotes: 2

Views: 4316

Answers (3)

Darin Dimitrov
Darin Dimitrov

Reputation: 1039398

Why do you need a constraint for a not null/empty match? Normally if you define your route like this:

context.MapRoute(
    "Accommodation_accomm_tags",
    "accomm/{controller}/{action}/{tag}",
    new { action = "Tags", controller = "AccommProperty" },
);

and tag is not specified in the request url this route simply won't match.

And if you want a token to be optional, then:

context.MapRoute(
    "Accommodation_accomm_tags",
    "accomm/{controller}/{action}/{tag}",
    new { action = "Tags", controller = "AccommProperty", tag = UrlParameter.Optional },
);

Constraints are used when you want to constrain the value of a given route token to some specific format.

Upvotes: 6

Cymen
Cymen

Reputation: 14429

At first, I tried to create a RegEx for empty string which is ^$ (which is what null would be). However, it doesn't look like route constraints can be !=. How about matching one or more character with ^.+$?

So:

tag = @"^.+$"

Upvotes: 2

Matthew Abbott
Matthew Abbott

Reputation: 61607

Could you create an IRouteConstraint:

public class NotNullRouteConstraint : IRouteConstraint
{
  public bool Match(
    HttpContextBase httpContext, Route route, string parameterName, 
    RouteValueDictionary values, RouteDirection routeDirection)
  {
    return (values[parameterName] != null);
  }
}

Which you can wire up:

context.MapRoute(
  "Accommodation_accomm_tags",
  "accomm/{controller}/{action}/{tag}",
  new { action = "Tags", controller = "AccommProperty" },
  new { tag = new NotNullRouteConstraint() }
);

Upvotes: 8

Related Questions