Route.Constraints Property
Definition
Important
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Gets or sets a dictionary of expressions that specify valid values for a URL parameter.
public:
property System::Web::Routing::RouteValueDictionary ^ Constraints { System::Web::Routing::RouteValueDictionary ^ get(); void set(System::Web::Routing::RouteValueDictionary ^ value); };
public System.Web.Routing.RouteValueDictionary Constraints { get; set; }
member this.Constraints : System.Web.Routing.RouteValueDictionary with get, set
Public Property Constraints As RouteValueDictionary
Property Value
An object that contains the parameter names and expressions.
Examples
The following example shows how to create a Route object and set the Constraints, DataTokens, and Defaults properties.
void Application_Start(object sender, EventArgs e)
{
RegisterRoutes(RouteTable.Routes);
}
public static void RegisterRoutes(RouteCollection routes)
{
Route reportRoute = new Route("{locale}/{year}", new ReportRouteHandler());
reportRoute.Defaults = new RouteValueDictionary { { "locale", "en-US" }, { "year", DateTime.Now.Year.ToString() } };
reportRoute.Constraints = new RouteValueDictionary { { "locale", "[a-z]{2}-[a-z]{2}" }, { "year", @"\d{4}" } };
reportRoute.DataTokens = new RouteValueDictionary { { "format", "short" } };
routes.Add(reportRoute);
}
Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
RegisterRoutes(RouteTable.Routes)
End Sub
Shared Sub RegisterRoutes(ByVal routes As RouteCollection)
Dim urlPattern As String
Dim reportRoute As Route
urlPattern = "{locale}/{year}"
reportRoute = New Route(urlPattern, New ReportRouteHandler)
reportRoute.Defaults = New RouteValueDictionary(New With {.locale = "en-US", .year = DateTime.Now.Year.ToString()})
reportRoute.Constraints = New RouteValueDictionary(New With {.locale = "[a-z]{2}-[a-z]{2}", .year = "\d{4}"})
reportRoute.DataTokens = New RouteValueDictionary(New With {.format = "short"})
routes.Add(reportRoute)
End Sub
The following example shows a Route object whose Constraints property contains a parameter named httpMethod
with an instance of the HttpMethodConstraint class for the value.
void Application_Start(object sender, EventArgs e)
{
RegisterRoutes(RouteTable.Routes);
}
public static void RegisterRoutes(RouteCollection routes)
{
string[] allowedMethods = { "GET", "POST" };
HttpMethodConstraint methodConstraints = new HttpMethodConstraint(allowedMethods);
Route reportRoute = new Route("{locale}/{year}", new ReportRouteHandler());
reportRoute.Constraints = new RouteValueDictionary { { "httpMethod", methodConstraints } };
routes.Add(reportRoute);
}
Sub Application_Start(ByVal sender As Object, ByVal e As EventArgs)
RegisterRoutes(RouteTable.Routes)
End Sub
Shared Sub RegisterRoutes(ByVal routes As RouteCollection)
Dim urlPattern As String
Dim reportRoute As Route
Dim allowedMethods() As String = {"GET", "POST"}
Dim methodConstraints As HttpMethodConstraint
methodConstraints = New HttpMethodConstraint(allowedMethods)
Dim constraintValues = New With {.httpMethod = methodConstraints}
urlPattern = "{locale}/{year}"
reportRoute = New Route(urlPattern, New ReportRouteHandler)
reportRoute.Constraints = New RouteValueDictionary(constraintValues)
routes.Add(reportRoute)
End Sub
Remarks
The Constraints property enables you to limit acceptable values for a URL parameter that is processed by a route. You assign a RouteValueDictionary object to the Constraints property. Each element in the RouteValueDictionary object contains the name of a parameter and one of the following:
A string that defines a regular expression. The regular expression is case-insensitive.
An object that implements the IRouteConstraint interface and that includes a Match method.
The HttpMethodConstraint class implements the IRouteConstraint interface. You can include an instance of the HttpMethodConstraint class as a constraint to specify which HTTP verbs are acceptable for the route.
Applies to
See also
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