Entity Framework Delete Object Problem

Asked 2009-08-01T17:21:54.843

i am getting "The object cannot be deleted because it was not found in the ObjectStateManager". while Deleting object.

here is codes ;

//first i am filling listview control.
 private void Form1_Load(object sender, EventArgs e)
    {
        FirebirdEntity asa = new FirebirdEntity();

        ObjectQuery<NEW_TABLE> sorgu = asa.NEW_TABLE;

        foreach (var item in sorgu)
        {
            ListViewItem list = new ListViewItem();
            list.Text = item.AD;
            list.SubItems.Add(item.SOYAD);
            list.Tag = item;
            listView1.Items.Add(list);

        }
//than getting New_table entity from listview's tag property.
 private void button3_Click(object sender, EventArgs e)
    {

            using (FirebirdEntity arama = new FirebirdEntity())
            {

               NEW_TABLE del = (NEW_TABLE)listView1.SelectedItems[0].Tag;
               arama.DeleteObject(del);
               arama.SaveChanges();


            }}

c# entity-framework ado.net

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2 Answers

I ran a linq query within my DomainService methods and then deleted from the result, so while the first snippet below failed with error "The object cannot be deleted because it was not found in the ObjectStateManager", the second snippet worked.

public void DeleteSharedDoc(SharedDocs shareddoc)
{
       this.ObjectContext.SharedDocs.DeleteObject(shareddoc);
}

This worked:

public void DeleteSharedDoc(SharedDocs shareddoc)
{
var query = (from w in this.ObjectContext.SharedDocs
            where w.UserShareName == shareddoc.UserShareName
            && w.UserShareUsersEmail == shareddoc.UserShareUsersEmail
            && w.DocumentId == shareddoc.DocumentId
            select w).First();
this.ObjectContext.SharedDocs.DeleteObject(query);
}

answered 2011-05-27T15:28:09.990

Assume I have an object called Department, with a surrogatekey DepartmentUUID

DDL looks like this:

CREATE TABLE [dbo].[Department] 
    ( 
          DepartmentUUID [UNIQUEIDENTIFIER] NOT NULL 
        , DepartmentName varchar(24) not null
        , CreateDate smalldatetime not null 
    )
GO


ALTER TABLE [dbo].[Department] ADD CONSTRAINT PK_Department PRIMARY KEY NONCLUSTERED (DepartmentUUID) 
GO

ALTER TABLE [dbo].[Department] ADD CONSTRAINT CK_DepartmentName_Unique UNIQUE (DepartmentName) 
GO

ALTER TABLE [dbo].[Department] ADD CONSTRAINT [DF_Department_DepartmentUUID] DEFAULT ( NEWSEQUENTIALID() ) FOR DepartmentUUID
GO

ALTER TABLE [dbo].[Department] ADD CONSTRAINT [DF_Department_CreateDate] DEFAULT ( CURRENT_TIMESTAMP ) FOR CreateDate
GO

Now for the Entity Framework code. The important parts are: 1. Using the AttachTo method. 2. Creating a temporary object, and setting the primary-key value of it. (surrogate key).

public int DeleteDepartment(Guid departmentUUID)
{

    int returnValue = 0;

    Department holder = new Department();
    holder.DepartmentUUID = departmentUUID; // DepartmentUUID is the primary key of this object (entity in the db)

    using (MyContectObject context = new MyContectObject())
    {
        context.AttachTo("Departments", holder);

        context.DeleteObject(holder);

        int numOfObjectsAffected = context.SaveChanges();
        returnValue = numOfObjectsAffected;

        context.Dispose();
    }

    return returnValue;

}

answered 2011-09-09T20:48:26.307

Entity Framework Delete Object Problem

2 Answers

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