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POGetting "An entity with the same identity already exists in this EntitySet" but the EntitySet is empty
 

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  1. POGetting "An entity with the same identity already exists in this EntitySet" but the EntitySet is empty
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    <p>When I try to add a new item to my EntitySet, I'm getting this exception:</p> <blockquote> <p>An entity with the same identity already exists in this EntitySet</p> </blockquote> <p>However, when I inspect the EntitySet its count is 0.</p> <p>Any ideas why I would be getting this error when the set is empty? How could an entity already exist in the set if the set has no items in it?</p> <p><strong>UPDATE</strong></p> <p>I've narrowed this down a bit more. This is only happening if I add the item to the set, remove it, then re-add it. Even tho the item isn't in the EntitySet any more it is still remembering it somehow. What do I need to do to make it forget?</p> <p><strong>UPDATE:</strong> Here are some code snippets for the classes and logic involved.</p> <p>Server Entities:</p> <pre><code>public class PhotoDto { [Key] [Editable(false)] public int Id { get; set; } /* clip */ [Include] [Association("Photo_Destination", "Id", "PhotoId")] public EntitySet&lt;PhotoDestinationDto&gt; Destinations { get; set; } } public class PhotoDestinationDto : BaseDestionationDto { [Key] [Editable(false, AllowInitialValue = true)] public int PhotoId { get; set; } [Key] [Editable(false, AllowInitialValue = true)] public bool IsAnnotated { get; set; } [Key] [Editable(false, AllowInitialValue = true)] public int DropZoneId { get; set; } } public class BaseDestinationDto { [Key] [Editable(false, AllowInitialValue = true)] public Guid DatabaseUid { get; set; } [Key] [Editable(false, AllowInitialValue = true)] public string Unit { get; set; } [Key] [Editable(false, AllowInitialValue = true)] public string EqCircId { get; set; } [Key] [Editable(false, AllowInitialValue = true)] public string EqType { get; set; } } </code></pre> <p>Client side GetIdentity() for PhotoDestinationDto:</p> <pre><code>/// &lt;summary&gt; /// Computes a value from the key fields that uniquely identifies this entity instance. /// &lt;/summary&gt; /// &lt;returns&gt;An object instance that uniquely identifies this entity instance.&lt;/returns&gt; public override object GetIdentity() { if ((((this._eqCircId == null) || (this._eqType == null)) || (this._unit == null))) { return null; } return EntityKey.Create(this._dropZoneId, this._eqCircId, this._eqType, this._isAnnotated, this._photoId, this._unit, this._databaseUid); } </code></pre> <p>To remove photo destination client side:</p> <pre><code>PhotoDto photo = GetPhotoDto(); PhotoDestinationDto destToRemove = photo.Destinations.First(x =&gt; x.DropZoneId == 1); photo.Destinations.Remove(destToRemove); </code></pre> <p>To add photo destination client side:</p> <pre><code>var dest = new PhotoDestinationDto { DropZoneId = zoneId, EqCircId = selectedEqCircId, EqType = selectedEqType, Unit = selectedUnit, PhotoId = id, DatabaseUid = selectedDatabaseId }; p.Destinations.Add(dest); // this is where exception is thrown. p.Destinations.Count is 0 here. </code></pre>
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      1. POGetting "An entity with the same identity already exists in this EntitySet" but the EntitySet is empty
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    1. COA shot in the dark: is the entity set missing the KeyAttribute ?
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    2. COI have an [Association] attribute on the actual EntitySet<T> property. The T type that is in the EntitySet<> also has properties with [Key] attributes.
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