我无法获取GtkTreeView的选定值

Question

tree_iter始终为无。 我试图更改代码，但仍然没有得到值。

def on_treeclients_cursor_changed(self, widget):                                                                      
    try:                                             
        (model, tree_iter) = variables.client_tree.get_selection().get_selected()                                                                                     
        if tree_iter is not None:                                                                                     
            dni = model.get_value(tree_iter, 0)                                                                       
            sec_name = model.get_value(tree_iter, 1)                                                                  
            name = model.get_value(tree_iter, 2)                                                                      
            date = model.get_value(tree_iter, 3)                                                                      
            client_id = client_functions.select_client(dni)                                                           

            variables.dni_message[1].modify_fg(Gtk.StateFlags.NORMAL, Gdk.color_parse('blue'))                        
            variables.dni_message[1].set_text(str(client_id[0]))                                                      
            variables.client_row[0].set_text(dni)                                                                     
            variables.client_row[1].set_text(sec_name)                                                                
            variables.client_row[2].set_text(name)                                                                    
            if date is not None:                                                                                      
                variables.client_row[3].set_text(str(date))                                                           
            else:                                                                                                     
                variables.client_row[3].set_text('-')                                                                 
    except Exception as e:                                                                                            
        print('[ERROR]\tCannot select client\n', e)                                                                                                                                                               ```