private void buttonSearchWorkExperience_Click(object sender, RoutedEventArgs e) { if (string.IsNullOrEmpty(comboBoxSearchWorkExperience.Text) == true) { MessageBox.Show("Please choice category search!"); } else { if (string.IsNullOrEmpty(textBoxSearchWorkExperience.Text) == true) { MessageBox.Show("Please insert keywoard search!"); } else if (string.IsNullOrWhiteSpace(textBoxSearchWorkExperience.Text) == true) { MessageBox.Show("Don't insert white space"); } else { dataGridWorkExperience.ItemsSource = _workExperienceService.Search(textBoxSearchWorkExperience.Text, comboBoxSearchWorkExperience.Text); } } }