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POMVC 3 Framework Edit and Details problems
 

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  1. POMVC 3 Framework Edit and Details problems
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    <h1>Background and Problem</h1> <p>I have successfully produced a database, models from the database, and controllers which produced default pages. The current problem that I am having is Edit and Delete pages, they are constantly producing problems and have tried </p> <ol> <li>Remove contexts and readd</li> <li>Delete the models and everything and re-add</li> </ol> <h2>The Problem statement that is produced when I click on the edit/delete pages from the details page:</h2> <p>Server Error in '/' Application.</p> <p>The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Edit(Int32)' in 'Olympics2012.Controllers.AthleteController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters</p> <p>Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. </p> <p>Exception Details: System.ArgumentException: The parameters dictionary contains a null entry for parameter 'id' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult Edit(Int32)' in 'Olympics2012.Controllers.AthleteController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters</p> <h2>Controller Edit Code</h2> <pre><code> public ActionResult Edit(int? id) { Athlete athlete = db.Athletes.Find(id); return View(athlete); } [HttpPost] public ActionResult Edit(Athlete athlete) { if (ModelState.IsValid) { db.Entry(athlete).State = EntityState.Modified; db.SaveChanges(); return RedirectToAction("Index"); } return View(athlete); } </code></pre>
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    1. COPut a breakpoint on the Edit action with the id as a parameter. What is the value of id?
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    2. COThe value of the id is a primary key from the Athletes table in the database
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    3. COOkay - why is the parameter nullable if it corresponds to a primary key?
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