c# – 如何在Windows窗体应用程序中实现控件验证？

我试图更好地了解验证如何在 Windows窗体应用程序中工作.互联网上充满了琐碎的例子,但我找不到一个解释控制验证的非平凡的例子.无论如何,多亏了 SwDevMan81和 Hans Passant,我从一个比昨天更好的地方开始.

“真正的应用程序”有一个包含许多TextBox控件的对话框.每个控件都实现Validating事件.正如您在示例中所看到的,ValidateChildren由于Click事件而被调用,导致Validating事件被发送到每个控件.该应用程序还使用ErrorProvider控件来提供用户反馈.昨天,我不明白如何使用Ok按钮Click事件来执行此验证.今天,我的对话框按预期工作.单击“确定”按钮会导致ErrorProvider执行控件无效且对话框未意外关闭的操作.

因此,虽然这似乎有效,但我感觉我“在线外”.在Windows窗体应用程序中是否有用于控制验证的“最佳实践”文档/站点？

在许多令我困惑的事情中,当Ok按钮DialogResult属性设置为返回DialogResult.OK时,我无法找到对话框行为的解释.为什么设置此属性会干扰验证？ (尝试使用和不使用该行的示例,看看我的意思.)

我昨天遇到的问题(看起来似乎)主要源于不了解ValidateChildren方法以及我将Ok按钮DialogResult属性设置为DialogResult.OK.将此属性设置为DialogResult.None似乎更改了Form类的一些自动行为.

TIA

using System;
using System.ComponentModel;
using System.Windows.Forms;

namespace ConsoleApp
{
    class Program
    {
        static void Main( string[] args )
        {
            Dialog dialog = new Dialog();

            if( dialog.ShowDialog() == DialogResult.OK )
                Console.Beep();
        }
    }

    public class Dialog : Form
    {
        TextBox m_TextBox0;
        TextBox m_TextBox1; // not validated
        TextBox m_TextBox2;

        Button m_OkBtn;
        Button m_CancelBtn;

        ErrorProvider m_ErrorProvider;

        public Dialog()
        {
            m_TextBox0 = CreateTextBox( 0,"TextBox 0" );
            m_TextBox1 = CreateTextBox( 1,"TextBox 1" );
            m_TextBox2 = CreateTextBox( 2,"TextBox 2" );

            m_OkBtn     = CreateButton( 3,"Ok" );
            m_CancelBtn = CreateButton( 4,"Cancel" );

            m_ErrorProvider = new ErrorProvider( this );

            //m_BtnOk.DialogResult = DialogResult.OK;
            m_OkBtn.Click += new EventHandler( BtnOk_Click );
            m_OkBtn.CausesValidation = true;

            m_CancelBtn.DialogResult = DialogResult.Cancel;
            m_CancelBtn.CausesValidation = false;
        }

        void BtnOk_Click( object sender,EventArgs e )
        {
            if( ValidateChildren() )
            {
                DialogResult = DialogResult.OK;
                Close();
            }
        }

        void TextBox_Validating( object sender,CancelEventArgs e )
        {
            m_ErrorProvider.Clear();

            TextBox textBox = sender as TextBox;

            // m_TextBox1 is always valid,the others are valid if they have text.
            bool valid = textBox.TabIndex == 1 || textBox.Text.Length > 0;

            if( !valid )
                m_ErrorProvider.SetError( textBox,"Error " + textBox.Name );

            e.Cancel = !valid;
        }

        Button CreateButton( int index,string name )
        {
            Button button = new Button();

            button.TabIndex = index;
            button.Text = name;
            button.Location = new System.Drawing.Point( 0,index * 30 );

            Controls.Add( button );

            return button;
        }

        TextBox CreateTextBox( int index,string name )
        {
            Label label = new Label();
            label.Text = name;
            label.Location = new System.Drawing.Point( 0,index * 30 );

            TextBox textBox = new TextBox();

            textBox.TabIndex = index;
            textBox.CausesValidation = true;
            textBox.Validating += new CancelEventHandler( TextBox_Validating );
            textBox.Location = new System.Drawing.Point( 100,index * 30 );

            Controls.Add( label );
            Controls.Add( textBox );

            return textBox;
        }
    }
}

编辑：这是最终的解决方案.我认为它很容易使用,同时也满足所有其他要求.我提前道歉这个问题到底有多长时间了.如果我可以向您展示所有真正的应用程序,那么为什么这么重要会更有意义.无论如何,感谢帮助这只老狗学习新技巧.

答案是为每个需要验证的控件创建一个ErrorProvider(相对于整个对话框的一个ErrorProvider.之后,一切都非常简单.

using System;
using System.ComponentModel;
using System.Windows.Forms;

namespace ConsoleApp
{
    class Program
    {
        static void Main( string[] args )
        {
            Dialog dialog = new Dialog();

            if( dialog.ShowDialog() == DialogResult.OK )
                Console.Beep();
        }
    }

    public class CompositeControl
    {
        Label         m_Label;
        TextBox       m_TextBox;
        ErrorProvider m_ErrorProvider;

        Dialog m_Dialog;

        public CompositeControl( int index,string name,Dialog dialog )
        {
            m_Label = new Label();
            m_Label.Text = name;
            m_Label.Location = new System.Drawing.Point( 0,index * 30 );

            m_TextBox = new TextBox();

            m_TextBox.TabIndex = index;
            m_TextBox.CausesValidation = true;
            m_TextBox.Validating += new CancelEventHandler( TextBox_Validating );
            m_TextBox.Location = new System.Drawing.Point( 100,index * 30 );

            m_Dialog = dialog;

            m_ErrorProvider = new ErrorProvider( m_Dialog );

            m_Dialog.Controls.Add( m_Label );
            m_Dialog.Controls.Add( m_TextBox );
        }

        void TextBox_Validating( object sender,CancelEventArgs e )
        {
            TextBox textBox = sender as TextBox;

            if( !m_Dialog.IsClosing && textBox.Text.Length == 0 )
                return;

            // m_TextBox1 is always valid,"Error " + textBox.Name );
            else
                m_ErrorProvider.Clear();

            e.Cancel = !valid;
        }
    }

    public class Dialog : Form
    {
        CompositeControl m_CompositeControl0;
        CompositeControl m_CompositeControl1; // not validated
        CompositeControl m_CompositeControl2;

        Button m_OkBtn;
        Button m_CancelBtn;

        bool m_IsClosing = false;

        public Dialog()
        {
            m_CompositeControl0 = new CompositeControl( 0,"TextBox 0",this );
            m_CompositeControl1 = new CompositeControl( 1,"TextBox 1",this );
            m_CompositeControl2 = new CompositeControl( 2,"TextBox 2",this );

            m_OkBtn     = CreateButton( 3,"Cancel" );

            //m_BtnOk.DialogResult = DialogResult.OK;
            m_OkBtn.Click += new EventHandler( BtnOk_Click );
            m_OkBtn.CausesValidation = true;

            m_CancelBtn.DialogResult = DialogResult.Cancel;
            m_CancelBtn.CausesValidation = false;
        }

        void BtnOk_Click( object sender,EventArgs e )
        {
            m_IsClosing = true;

            if( ValidateChildren() )
            {
                DialogResult = DialogResult.OK;
                Close();
            }

            m_IsClosing = false;
        }

        Button CreateButton( int index,index * 30 );

            Controls.Add( button );

            return button;
        }

        public bool IsClosing { get { return m_IsClosing; } }
    }
}

这个问题是我昨天问到的one的后续问题.