private void btnDeleteTask_Click(object sender) { if (projectproject_template_detailViewSource.View != null) { projectproject_template_detailViewSource.View.Filter = null; List <project_template_detail> project_template_detailLIST = treeProject.ItemsSource.Cast <project_template_detail>().ToList(); project_template_detailLIST = project_template_detailLIST.Where(x => x.IsSelected == true).ToList(); using (db db = new db()) { foreach (project_template_detail project_template_detail in project_template_detailLIST) { project_template_detail _project_template_detail = db.project_template_detail.Where(x => x.id_template_detail == project_template_detail.id_template_detail).FirstOrDefault(); db.project_template_detail.Remove(_project_template_detail); } db.SaveChanges(); } ProjectTemplateDB = new ProjectTemplateDB(); project_templateViewSource = ((CollectionViewSource)(FindResource("project_templateViewSource"))); ProjectTemplateDB.project_template.Where(a => a.id_company == CurrentSession.Id_Company).Load(); project_templateViewSource.Source = ProjectTemplateDB.project_template.Local; filter_task(); } }