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POASP.NET MVC EF Code first: Relation can not be modified
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  1. POASP.NET MVC EF Code first: Relation can not be modified
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    copied!<p>When my code reaches CampaignRepository.saveChanges() it gives and error that the relation can not be modified, key properties can not be null. But if I debug it and look into the contents of the current object all primary keys and foreign keys are set. I have no clue why it's going wrong...</p> <pre><code>public ActionResult Update(LandingPage update) { Campaign curr = CampaignRepository.FindById(update.CampaignId); curr.UpdatePage(update); CampaignRepository.SaveChanges(); return View("Edit", curr); } </code></pre> <hr> <pre><code> public void UpdatePage(LandingPage update) { foreach (Page page in Pages) { if (page.Id == update.Id) { Pages.Remove(page); break; } } Pages.Add(update); } </code></pre> <blockquote> <p>de relatie kan niet worden gewijzigd, omdat voor een of meer van de referentiële-sleuteleigenschappen geen null-waarde is toegestaan. Wanneer een relatie wordt gewijzigd, wordt de gerelateerde referentiële-sleuteleigenschap ingesteld op een null-waarde. Als de referentiële sleutel null-waarden niet ondersteunt, moet er een nieuwe relatie worden gedefinieerd, moet de referentiële-sleuteleigenschap worden toegewezen aan een andere waarde die niet null is of moeten het niet-gerelateerde object worden verwijderd.</p> </blockquote> <hr> <p><strong>Update</strong></p> <p>I changed my Update method to:</p> <pre><code> public ActionResult Update(LandingPage update) { Campaign curr = Campaignrepository.FindById(update.CampaignId); PageRepository.Remove(update); curr.Pages.Remove(update); curr.Pages.Add(update); Campaignrepository.SaveChanges(); return View("Edit", curr); } </code></pre> <p>But now it says "The Object can not be removed because it's not found in the ObjectManager".</p> <hr> <p><strong>Update 2</strong></p> <p>Still "The Object can not be removed because it's not found in the ObjectManager". </p> <pre><code> //A campaign has Pages property which is a collection of Pages //This collection contains a two (no more, no less) objects a LandingPage and a RedeemPage //both LandingPage and RedeemPage have as base Page //The objective is to replace the old LandingPage with the new version public ActionResult Update(LandingPage update) { //Get the campaign it's about Campaign curr = Campaignrepository.FindById(update.CampaignId); //Set the current Page his foreign key values to null curr.GetLanding().Campaign = null; curr.GetLanding().CampaignId = 0; //Remove the (current) page from the repository/context PageRepository.Remove(update); //Remove the (current) page from the Campaign collection curr.Pages.Remove(update); //Add the new version of the page curr.Pages.Add(update); //Save the chances =&gt; ObjectManager error PageRepository.SaveChanges(); return View("Edit", curr); } </code></pre>
 

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