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POCan't update a record using entity framework and ninject with Repository pattern
 

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  1. POCan't update a record using entity framework and ninject with Repository pattern
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    <p>I am using MVC3, Ninject , Ninject MVC extensions, EF 4.1</p> <p>I have implemented the following repo pattern.</p> <p>Repository.cs</p> <pre><code>public interface IRepository&lt;T&gt; where T : class { IQueryable&lt;T&gt; AsQueryable(); IEnumerable&lt;T&gt; GetAll(); IEnumerable&lt;T&gt; Find(Expression&lt;Func&lt;T, bool&gt;&gt; where); T Single(Expression&lt;Func&lt;T, bool&gt;&gt; where); T First(Expression&lt;Func&lt;T, bool&gt;&gt; where); void Delete(T entity); void Add(T entity); void Attach(T entity); } public class Repository&lt;T&gt; : IRepository&lt;T&gt; where T : class { IObjectSet&lt;T&gt; _objectSet; public Repository(IObjectContext objectContext) { _objectSet = objectContext.CreateObjectSet&lt;T&gt;(); //_objectSet.MergeOption = MergeOption.NoTracking; } public IQueryable&lt;T&gt; AsQueryable() { return _objectSet; } public IEnumerable&lt;T&gt; GetAll() { return _objectSet.ToList(); } public IEnumerable&lt;T&gt; Find(Expression&lt;Func&lt;T, bool&gt;&gt; where) { return _objectSet.Where(where); } public T Single(Expression&lt;Func&lt;T, bool&gt;&gt; where) { return _objectSet.Single(where); } public T First(Expression&lt;Func&lt;T, bool&gt;&gt; where) { return _objectSet.First(where); } public void Delete(T entity) { _objectSet.DeleteObject(entity); } public void Add(T entity) { _objectSet.AddObject(entity); } public void Attach(T entity) { _objectSet.Attach(entity); } } </code></pre> <p>Unit of Work.cs</p> <pre><code> public interface IUnitOfWork { void Commit(); } public class UnitOfWork : IUnitOfWork, IDisposable { private readonly IObjectContext _objectContext; public UnitOfWork(IObjectContext objectContext) { _objectContext = objectContext; } public void Dispose() { if (_objectContext != null) { _objectContext.Dispose(); } GC.SuppressFinalize(this); } public void Commit() { _objectContext.SaveChanges(); } } </code></pre> <p>ObjectContext.cs</p> <pre><code>public interface IObjectContext : IDisposable { IObjectSet&lt;T&gt; CreateObjectSet&lt;T&gt;() where T : class; void SaveChanges(); } public class ObjectContextAdapter : IObjectContext { readonly ObjectContext _context; public ObjectContextAdapter(ObjectContext context) { _context = context; } public void Dispose() { _context.Dispose(); } public IObjectSet&lt;T&gt; CreateObjectSet&lt;T&gt;() where T : class { return _context.CreateObjectSet&lt;T&gt;(); } public void SaveChanges() { _context.SaveChanges(); } } </code></pre> <p>I have used Ninject to bind them in the IOC using the following implementation</p> <pre><code> public override void Load() { Bind(typeof(IRepository&lt;&gt;)).To(typeof(Repository&lt;&gt;)); Bind&lt;IObjectContext&gt;().To&lt;ObjectContextAdapter&gt;().WithConstructorArgument("context", new MGTContainer()); Bind&lt;IUnitOfWork&gt;().To&lt;UnitOfWork&gt;(); } </code></pre> <p>The repo pattern is taken from here <a href="http://elegantcode.com/2009/12/15/entity-framework-ef4-generic-repository-and-unit-of-work-prototype/" rel="nofollow">Repo Pattern Implementation</a></p> <p>Here is a sample use of the pattern in the controller</p> <pre><code> eventRepository.Attach(model); unitOfWork.Commit(); </code></pre> <p>All works fine for Inserting, Reading and Deleting records but when i call the attach i have the following error</p> <blockquote> <p>An object with the same key already exists in the ObjectStateManager. The ObjectStateManager cannot track multiple objects with the same key.</p> </blockquote> <p>I have tried changing the binding to InRequestScope but this causes subsequent errors.</p> <p>Thanks in advance for your help</p>
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      1. POCan't update a record using entity framework and ninject with Repository pattern
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    1. COCan you show the full code which throws the exception? Creating a context, calling `Attach` and `SaveChanges` doesn't cause such exception.
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      1. USSlauma
    2. COThe context is created in the IOC binding, I have already included the call to the attach method and the unitof work commit call which will then call the submitchanges method. Not sure what else you need.
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      1. USSi Robinson
    3. COWhat is `model` and where does it come from? Read the exception carefully: It talks about **multiple** objects in the ObjectStateManager. Where does the at least second object with the same key come from? Your code shows only one single object called `model` at all. Another problem might be that your context doesn't get disposed after a web request. Then old objects (with same key!) from earlier requests might still be in the context, causing the exception. `InRequestScope` sounds actually good for a web app. Are you sure that you don't need to use this binding?
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      1. USSlauma
 

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