ASP.NET MVC Controller Code Contracts and Properties

Question

I am using CodeContracts for the first time, and I have a question regarding this. When I use the ModelState, User, Requestor Responsein my controller code, then Code Contracts states that I need to add Contract.Requires(this.Request != null)in your own code.

Message example:

Warning 1 CodeContracts: There is no precondition in the external visible method. Try adding Contract.Requires (this.ModelState! = Null); to check the parameters

I thought I could remove these messages from code contracts by adding:

[ContractInvariantMethod]
private void ObjectInvariant()
{
    Contract.Invariant(this.HttpContext != null);
    Contract.Invariant(this.ModelState != null);
    Contract.Invariant(this.Request != null);
    Contract.Invariant(this.Response != null);
    Contract.Invariant(this.RouteData != null);
    Contract.Invariant(this.Server != null);
    Contract.Invariant(this.Session != null);
    Contract.Invariant(this.ViewData != null);
    Contract.Invariant(this.User != null);
    Contract.Invariant(this.Url != null);
}

In my code. But the ObjectInvariant function is checked at runtime before the Controller.Initialize is called so that all invariants are false.

---

TL DR

: ?

Answer 1

Code Contracts MVC-. , (, "-" ), " ".

. , , (.. , , , , ).

Answer 2

- ContractFailed , :

Contract.ContractFailed += (sender, args) => 
{ 
   //additionally you can check args.FailureKind to distinguish what exactly has failed (if needed)

   args.SetHandled(); 
};

, , . - :

[SuppressMessage("Microsoft.Contracts", "Invariant")]
//or this: [SuppressMessage("Microsoft.Design", "CA1062:Validate arguments of public methods")]
public ActionResult Index()
{
    Contract.Requires(Request != null);
    //...
    return View();
}

:

[ContractVerification(false)]

- () , ( Contract.Invariant(this.Request!= null))

Answer 3

The answer lies in the error "Lack of precondition in the external visible method." Your method is confidential. Try public void ObjectInvariant ()