如何检查多个组合框的值是否为空

Question

我的win-form应用程序中有40个组合框，我想在按钮单击结束时检查是否已输入所有组合框值，即没有选择任何组合框值

我正在尝试下面的代码用于每个循环，但找不到成功

foreach (Control c in this.Controls)
{
      if (c is ComboBox)
      {
           ComboBox textBox = c as ComboBox;
           if (textBox.SelectedValue==string.Empty)
           {
               MessageBox.Show("please fill all fields");
           }
      }
}

那么如何用简单的代码行来实现这种验证

Answer 1

尝试使用linq和递归：

var isAnyEmpty = ScanForControls<ComboBox>(this)
   .Where(x => x.SelectedIndex < 0)
   .Any();

if (isAnyEmpty)
    MessageBox.Show("please fill all fields");

和递归搜索：

public IEnumerable<T> ScanForControls<T>(Control parent) where T : Control
{
    if (parent is T)
        yield return (T)parent;

    foreach (Control child in parent.Controls)
    {
        foreach (var child2 in ScanForControls<T>(child))
            yield return (T)child2;
    }
}

Answer 2

为确保检查表单中的每个ComboBox，您必须遍历Form中的每个控件，为此请尝试一下。

private void button1_Click(object sender, EventArgs e)
{
   foreach (Control c in this.Controls)
   {
      if (c is ComboBox)
      {
         ComboBox textBox = c as ComboBox;
         if (textBox.SelectedValue == null)
         {
            MessageBox.Show("please fill all fields");
            break;
         }
       }
       else
          recursiveComboboxValidator(c);
    }
}

void recursiveComboboxValidator(Control cntrl)
{
    foreach (Control c in cntrl.Controls)
    {
       if (c is ComboBox)
       {
           ComboBox textBox = c as ComboBox;
           if (textBox.SelectedValue == null)
           {
                MessageBox.Show("please fill all fields");
                break;
           }
        }
        else
            recursiveComboboxValidator(c);
     }
}