Monday, 23 January 2017

c# - How to "EnforceConstraints" to avoid linq errors?



I'm working on a sample from the book I bought. And, for unknown reason, I get the following error message " Could not find an implementation of the query pattern for source type 'System.Type'. 'Where' not found."



The VS2008 help says that I need to add System.Linq and System.Collections namespaces to solve the issue. Unfortunatelly, I still get the same error message. In MSDN forum, it said that I need to set EnforceConstraints to true;



I would like to know what's "EnforceConstraints" and how can I do it.




Thanks.








using System;
using System.Data;
using System.Configuration;

using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.Web.Mvc;
using Castle.Windsor;

using Castle.Windsor.Configuration.Interpreters;
using Castle.Core.Resource;
using System.Reflection;
using Castle.Core;
using System.Collections;



namespace WebUI
{
public class WindsorControllerFactory : DefaultControllerFactory
{

WindsorContainer Container;



    public WindsorControllerFactory()
{
//Instatiate a container, taking configuration from web.conf
Container = new WindsorContainer(
new XmlInterpreter(new ConfigResource("Castle"))
);

//Also register all the controller types as transient

var controllerTypes =
from t in Assembly.GetExecutingAssembly().GetType()
where typeof(IController).IsAssignableFrom(t)
select t;
foreach (Type t in controllerTypes)
Container.AddComponentWithLifestyle(t.FullName, t, LifestyleType.Transient);
}

//Constructs the controller instance needed to service each request
protected override IController GetControllerInstance(Type controllerType)

{
return (IController)Container.Resolve(controllerType);
}

}//The constructor
}






The sample is on page 98.



the book is "Pro ASP.NET MVC Framework"/Steven Sanderson/APress ISBN-13 (pbk): 978-1-4302-1007-8


Answer



In the line:



from t in Assembly.GetExecutingAssembly().GetType()


you are missing a 's' at the end of GetTypes(). This should solve the problem, as GetType() is returning a single Type instance, whereas GetTypes() returns an array of Type objects.



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