Question

I know this question has been asked many times and after going through posts, I believe it has something to do with entity name, but I am completely new to data entity model and while trying to do a simple insert of a blog entry with blog details, I encountered this problem.

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.

Exception Details: System.ArgumentException: An item with the same key has already been added.

Source Error:

Line 365:    public void AddToblogs(blog blog)
Line 366:    {
Line 367:        base.AddObject("myblogs", blog);
Line 368:    }
Line 369:


Source File: C:\Inetpub\int422_113b16\webcontent\App_Code\blogModel.cs    Line: 367

Stack Trace:

[ArgumentException: An item with the same key has already been added.]
   System.ThrowHelper.ThrowArgumentException(ExceptionResource resource) +52
   System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add) +9382923
   System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.LoadRelationshipTypes() +661
   System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.LoadTypesFromAssembly() +17
   System.Data.Metadata.Edm.ObjectItemAssemblyLoader.Load() +25
   System.Data.Metadata.Edm.ObjectItemAttributeAssemblyLoader.Load() +4
   System.Data.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, ObjectItemLoadingSessionData loadingData) +160
   System.Data.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, KnownAssembliesSet knownAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage, Object& loaderCookie, Dictionary`2& typesInLoading, List`1& errors) +166
   System.Data.Metadata.Edm.ObjectItemCollection.LoadAssemblyFromCache(ObjectItemCollection objectItemCollection, Assembly assembly, Boolean loadReferencedAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage) +316
   System.Data.Metadata.Edm.ObjectItemCollection.ImplicitLoadAssemblyForType(Type type, EdmItemCollection edmItemCollection) +84
   System.Data.Metadata.Edm.MetadataWorkspace.ImplicitLoadAssemblyForType(Type type, Assembly callingAssembly) +151
   System.Data.Objects.ObjectContext.AddObject(String entitySetName, Object entity) +211
   blogEntities.AddToblogs(blog blog) in C:\Inetpub\int422_113b16\webcontent\App_Code\blogModel.cs:367
   BlogManager.BlogAdd(String title, String content, String userName) in C:\Inetpub\int422_113b16\webcontent\App_Code\BlogManager.cs:27
   Project_Admin_create_post.post_Click(Object sender, EventArgs e) in C:\Inetpub\int422_113b16\webcontent\Project\Admin\create-post.aspx.cs:25
   System.Web.UI.WebControls.Button.OnClick(EventArgs e) +118
   System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) +112
   System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) +10
   System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) +13
   System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) +36
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +5563

BlogManager.cs

public class BlogManager
{
    private blogEntities _dbEnt = new blogEntities();

    public BlogManager()
    {
    }

    public void BlogAdd(int numId, string title, string content,string userName) 
    {

        blog newPost = new blog();
        newPost.blog_id = 1;
        newPost.blog_title = title;
        newPost.blog_content = content;
        newPost.date_created = null;
        newPost.user_name = userName;

        _dbEnt.AddTotheblog(newPost);
        _dbEnt.SaveChanges();
    }

    public class NameNotUniqueException : Exception
    {
        public NameNotUniqueException(string msg = "INT422 ERROR: matching data already exists")
            : base(msg)
        { }
    }
}

create-post.cs

public partial class Project_Admin_create_post : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (IsPostBack)
        {
            blogStatus.Text = "Your post is published";
            title.Enabled = false;
            content.Enabled = false;
        }
    }

    protected void post_Click(object sender, EventArgs e)
    {
        string _userName = User.Identity.Name;

        BlogManager blogMgr = new BlogManager();
        blogMgr.BlogAdd(title.Text, content.Text, _userName);
    }
}

Answer 1

I think the error message is telling you the truth here. You’ve previously, either in a child object in your blog post, or the blog post itself—added another entity of this type with the same entity key.

Is it possible that in one of your tables you’ve forgotten to set the identity key for your PK? If so you might have a row with a key of 0, and subsequent inserts are conflicting with it.