DefaultInlineConstraintResolver Error in WebAPI 2

Question

I\'m using Web API 2 and I\'m getting the following error when I send a POST to my API method using IIS 7.5 on my local box.

The inline constraint resolver o         


        

Answer 1

I designed a API route for one Undo Web API method and I tried to apply ENUM datatype validation on action in route and encountered below DefaultInlineConstrainResolver Error

Error: System.InvalidOperationException: 'The inline constraint resolver of type 'DefaultInlineConstraintResolver' was unable to resolve the following inline constraint: 'ActionEnum’

[HttpGet]
[Route("api/orders/undo/{orderID}/action/{actiontype: OrderCorrectionActionEnum}")]
public IHttpActionResult Undo(int orderID, OrderCorrectionActionEnum actiontype)
{
    _route(undo(orderID, action);
}

public enum OrderCorrectionActionEnum
{
    [EnumMember]
    Cleared,

    [EnumMember]
    Deleted,
}

To apply ENUM constrain, you have to create custom OrderCorrectionEnumRouteConstraint by using IHttpRouteConstraint.

public class OrderCorrectionEnumRouteConstraint : IHttpRouteConstraint
{
    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        // You can also try Enum.IsDefined, but docs say nothing as to
        // is it case sensitive or not.
        var response = Enum.GetNames(typeof(OrderCorrectionActionEnum)).Any(s = > s.ToLowerInvariant() == values[parameterName].ToString().ToLowerInvariant());
        return response;
    }

    public bool Match(HttpRequestMessage request, IHttpRoute route, string parameterName, IDictionary< string, object> values, HttpRouteDirection routeDirection)
    {
        bool response = Enum.GetNames(typeof(BlockCorrectionActionEnum)).Any(s = > s.ToLowerInvariant() == values[parameterName].ToString().ToLowerInvariant());
        return response;              
    }
}

Reference (This is my blog): https://rajeevdotnet.blogspot.com/2018/08/web-api-systeminvalidoperationexception.html for more details