当向Gridview返回大量记录时产生NullReferenceException

本文关键字：NullReferenceException 记录 Gridview 返回 当向 | 更新日期: 2023-09-27 18:18:47

我目前正在使用givenName*和sn*搜索AD。以下代码仅在结果很小的情况下有效。当结果相当大时，它不起作用。我不明白为什么返回一个空引用。

            DataTable userTable = new DataTable();
            try
            {
                searchUser.Filter = "(&(objectClass=user)(&(givenName=" + FirstName.Text.Trim() + "*)(sn=" + LastName.Text.Trim() + "*)))";
               // searchUser.PropertiesToLoad.AddRange(new String[] { "displayName", "extensionAttribute13", "description" });
                searchUser.PropertiesToLoad.Add("displayname");
                searchUser.PropertiesToLoad.Add("extensionAttribute13");
                searchUser.PropertiesToLoad.Add("description");
                SearchResultCollection multipleResults = searchUser.FindAll();

                userTable.Columns.Add("Name",System.Type.GetType("System.String"));
                userTable.Columns.Add("Gentiva ID", System.Type.GetType("System.String"));
                userTable.Columns.Add("Location", System.Type.GetType("System.String"));
                foreach (SearchResult result in multipleResults)
                {
                    DataRow dr = userTable.NewRow();
                    DirectoryEntry de = result.GetDirectoryEntry();
                    if (result.GetDirectoryEntry().Properties != null)
                    {
                        if(result.GetDirectoryEntry().Properties["displayname"].Value==null)
                        {
                            dr["Name"] = " ";
                            // MessageBox.Show("Null Hit - display");
                        }
                        else if (result.GetDirectoryEntry().Properties["displayname"].Value != null)
                        {
                            dr["Name"] = (string)de.Properties["displayname"].Value.ToString();
                        }           
                        if (result.GetDirectoryEntry().Properties["extensionAttribute"].Value == null)
                        {
                            dr["Gentiva ID"] = " ";
                           // MessageBox.Show("Null Hit - extensions");
                        }
                        else if (result.GetDirectoryEntry().Properties["extensionAttribute"].Value != null)
                        {
                            dr["Gentiva ID"] = (string)de.Properties["extensionAttribute"].Value.ToString();
                        }  
                        if (result.GetDirectoryEntry().Properties["description"].Value == null)
                        {
                            dr["Location"] = " ";
                            // MessageBox.Show("Null Hit - description");
                        }
                        else if (result.GetDirectoryEntry().Properties["description"].Value != null)
                        {
                            dr["Location"] = (string)de.Properties["displayname"].Value.ToString();
                        }
                        userTable.Rows.Add(dr);
                        de.Close();
                        de.Dispose();
                    }
                    else
                    {
                       // MessageBox.Show("Null Hit");                               
                    }
                }
                grdviewMultiple.ItemsSource = userTable.AsDataView();
                grdviewMultiple.Visibility = Visibility.Visible;
            }
            catch(Exception ex)
            {
                throw ex;
            }

当向Gridview返回大量记录时产生NullReferenceException

尝试下面的操作，只是复制粘贴到您已有的文件中，并确保您调试了它。在我看来，大数据实际上与你的问题无关，我认为你没有做适当的检查和/或类型转换，你得到了一个错误

try
{
    searchUser.Filter = "(&(objectClass=user)(&(givenName=" + FirstName.Text.Trim() + "*)(sn=" + LastName.Text.Trim() + "*)))";
    searchUser.PropertiesToLoad.AddRange(new String[] { "displayName", "extensionAttribute13", "description" });
    SearchResultCollection multipleResults = searchUser.FindAll();
    DataTable userTable = new DataTable();
    userTable.Columns.Add("Name", System.Type.GetType("System.String"));
    userTable.Columns.Add("Gentiva ID", System.Type.GetType("System.Int32"));
    userTable.Columns.Add("Location", System.Type.GetType("System.String"));
    foreach (SearchResult result in multipleResults)
    {
        DataRow dr = userTable.NewRow();
        DirectoryEntry de = result.GetDirectoryEntry();
        if (result.GetDirectoryEntry().Properties != null)
        {
            if(result.GetDirectoryEntry().Properties["displayname"].Value==null)
            {
                dr["Name"] = "";
            }
            else
            {
              dr["Name"] = (string)de.Properties["displayname"].Value.ToString();
            }           
            if (result.GetDirectoryEntry().Properties["extensionAttribute"].Value == null)
            {
                dr["Gentiva ID"] = DBNull.Value; 
            }
            else
            {
                dr["Gentiva ID"] = (int)de.Properties["extensionAttribute13"].Value;
            }
            if (result.GetDirectoryEntry().Properties["description"].Value == null)
            {
                dr["Location"] = "";
            }
            else
            {
                dr["Location"] = (string)de.Properties["description"].Value.ToString();
            }
        }       
        userTable.Rows.Add(dr);
    }
    de.Close();
    de.Dispose();
    grdviewMultiple.ItemsSource = userTable.AsDataView();
    grdviewMultiple.Visibility = Visibility.Visible;
}
catch(ActiveDirectoryOperationException adEx)
{
    MessageBox.Show(adEx.ToString());
    de.Close();
    de.Dispose()
}
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