c# – 使用Validating事件和ErrorProvider进行验证 – 显示错误摘要

如何在WinForms中遗留错误时显示Messagebox“数据无效”.
尝试了类似但不起作用的东西.

if (errorprovider1 == !null)
{
 MessageBox.Show("Data is invalid");
}

也许我必须使用bool来解决这个问题.

我的完整代码：

private void Form1_Load(object sender, EventArgs e)
{
    this.Text = "Formas elementu validācija";
}

    private void textBox1_Validating(object sender, CancelEventArgs e)
    {
        Regex regex1 = new Regex(@"^[a-zA-Z]+$");
        if (!regex1.IsMatch(textBox1.Text))
        {
            errorProvider1.SetError(textBox1, "Nosaukums nedrīskt saturēt ciparus!");
        }
        else
        {
            errorProvider1.Clear();
        }
    }

    private void textBox2_Validating(object sender, CancelEventArgs e)
    {
        Regex regex1 = new Regex(@"^[0-9]+$");
        if (!regex1.IsMatch(textBox2.Text))
        {
            errorProvider2.SetError(textBox2, "Reģ.nur drīkst saturēt TIKAI ciparus!");
        }
        else
        {
            errorProvider2.Clear();
        }
    }

    private void button1_Click(object sender, EventArgs e)
    {
        // if errorProvider1 is empty (no errors) , show messagebox with text: All data correct.
        // else Data is incorrect.
    }

您应该首先以这种方式更正您的验证事件：

private void textBox1_Validating(object sender, CancelEventArgs e)
{
    Regex regex1 = new Regex(@"^[a-zA-Z]+$");
    if (!regex1.IsMatch(textBox1.Text))
    {
        //To set validation error
        errorProvider1.SetError(textBox1, "Nosaukums nedrīskt saturēt ciparus!");
        //To say the state of control in invalid
        e.Cancel = true;
    }
    else
    {
        //To clear the validation error
        this.errorProvider1.SetError(this.textBox1, "");
    }
}

然后你应该使用ValidateChildren方法检查是否存在验证错误,然后你可以获得所有错误的列表并以这种方式显示给用户：

private void button1_Click(object sender, EventArgs e)
{
    if (this.ValidateChildren())
    {
        //Here the form is in valid state
        //Do what you need when the form id valid
    }
    else
    {
        var listOfErrors = this.errorProvider1.ContainerControl.Controls.Cast<Control>()
                               .Select(c => this.errorProvider1.GetError(c))
                               .Where(s => !string.IsNullOrEmpty(s))
                               .ToList();
        MessageBox.Show("Please correct validation errors:\n - " +
            string.Join("\n - ", listOfErrors.ToArray()),
            "Error",  
            MessageBoxButtons.OK, MessageBoxIcon.Error);
    }
}

示例截图：

注意：

>你不应该使用Clear错误提供程序的方法来设置有效状态来控制,你应该使用SetError,例如this.errorProvider1.SetError(textBox2,“”);
>当出现验证错误时,您应该调用e.Cancel = true.
>在示例代码中,我假设您的所有控件(包括错误提供程序)都直接放在您的表单上,而不是放在容器控件中.
>我还建议通过在表单的Load事件中按代码的设计时间将表单的AutoValidate属性设置为EnableAllowFocusChange来更改表单的验证行为：

要更改表单的验证行为：

this.AutoValidate = System.Windows.Forms.AutoValidate.EnableAllowFocusChange;