如何使用 TextChanged 从字段 B 重新检查字段 A？

Question

我这里遇到一个小问题。这是我的情况：

我输入用户名：tester（有效用户名；避免所有检查），然后输入密码：testerr（有效密码；避免所有检查）。问题是我正在检查相同的输入。在我的代码中，当两个输入相同时，我会看到一条通知。现在，当我输入 tester 作为用户名和密码时，我收到错误，但是当我向密码“testerr”添加附加字符时，我使密码有效，但用户名被检查为无效，说明两者仍然相同，并且使我的验证不可能。

如何避免这种情况呢？我正在考虑重新检查字段 2 中的用户名字段，但我不确定如何进行。

bool passIsValid, userIsValid;

public AuthenticationWindow()
{
    InitializeComponent();

    // Creating TextChanged events which till validate input fields.
    txtUserName.TextChanged += new EventHandler(txtUserName_TextChanged);
    txtPassword.TextChanged += new EventHandler(txtPassword_TextChanged);
}

private void txtUserName_TextChanged(object sender, EventArgs e)
{
    // Checking for empty user name field.
    if (string.IsNullOrEmpty(txtUserName.Text))
    {
        lblMessageUser.Text = "User Name field cannot be empty!";
        lblMessageUser.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
    }
    // Making sure that user name is at least 6 characters long.
    else if (txtUserName.Text.Length < 6)
    {
        lblMessageUser.Text = "User Name field must be at least 6 characters long!";
        lblMessageUser.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
    }
    // Checking for user name made of same repeating character.
    // Invalid example: 'aaaaaa'
    else if (!txtUserName.Text.Distinct().Skip(1).Any())
    {
        lblMessageUser.Text = "User Name cannot be made of repeating the same characters!";
        lblMessageUser.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
    }
    // Making sure that password and user name aren't the same.
    else if (txtUserName.Text == txtPassword.Text)
    {
        lblMessageUser.Text = "User Name and Password can not be the same!";
        lblMessagePass.Text = "User Name and Password can not be the same!";
        lblMessageUser.ForeColor = Color.IndianRed;
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
        passIsValid = false;
    }
    // If all other checks aren't trigered; enable authentication.
    else
    {
        lblMessageUser.Text = "User Name is valid.";
        lblMessageUser.ForeColor = Color.Green;

        userIsValid = true;

        if (passIsValid && userIsValid)
        {
            btnAuthenticate.Enabled = true;
        }
    }
}

private void txtPassword_TextChanged(object sender, EventArgs e)
{
    // Checking for Null or Empty string in password field.
    if (string.IsNullOrEmpty(txtPassword.Text))
    {
        lblMessagePass.Text = "Password field cannot be empty!";
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        passIsValid = false;
    }
    // Making sure that password is at least 6 characters long.
    else if (txtPassword.Text.Length < 6)
    {
        lblMessagePass.Text = "Password field must be at least 6 characters long!";
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        passIsValid = false;
    }
    // Checking for password made of same repeating character.
    // Invalid example: 'aaaaaa'
    else if (!txtPassword.Text.Distinct().Skip(1).Any())
    {
        lblMessagePass.Text = "Password cannot be made of repeating the same characters!";
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        passIsValid = false;
    }
    // Making sure that user name and password are not the same.
    // Security measure.
    else if (txtUserName.Text == txtPassword.Text)
    {
        lblMessageUser.Text = "User Name and Password can not be the same!";
        lblMessagePass.Text = "User Name and Password can not be the same!";
        lblMessageUser.ForeColor = Color.IndianRed;
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
        passIsValid = false;
    }
    // If all other checks aren't trigered; enable authentication.
    else
    {
        lblMessagePass.Text = "Password is valid.";
        lblMessagePass.ForeColor = Color.Green;

        passIsValid = true;

        if (passIsValid && userIsValid)
        {
            btnAuthenticate.Enabled = true;
        }
    }
}

Answer 1

您可以将这两个事件合并为一个，然后用户会看到所有错误，并且您的检查可能会成功。

bool passIsValid, userIsValid;

public AuthenticationWindow()
{
    InitializeComponent();

    // Creating TextChanged events which till validate input fields.
    txtUserName.TextChanged += new EventHandler(txtCheck_TextChanged);
    txtPassword.TextChanged += new EventHandler(txtCheck_TextChanged);
}

private void txtCheck_TextChanged(object sender, EventArgs e)
{
    // Checking for empty user name field.
    if (string.IsNullOrEmpty(txtUserName.Text))
    {
        lblMessageUser.Text = "User Name field cannot be empty!";
        lblMessageUser.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
    }
    // Making sure that user name is at least 6 characters long.
    else if (txtUserName.Text.Length < 6)
    {
        lblMessageUser.Text = "User Name field must be at least 6 characters long!";
        lblMessageUser.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
    }
    // Checking for user name made of same repeating character.
    // Invalid example: 'aaaaaa'
    else if (!txtUserName.Text.Distinct().Skip(1).Any())
    {
        lblMessageUser.Text = "User Name cannot be made of repeating the same characters!";
        lblMessageUser.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
    }
    else
    {
        userIsValid = true;
        lblMessageUser.Text = "Password is valid.";
        lblMessageUser.ForeColor = Color.Green;
    }

    // Checking for Null or Empty string in password field.
    if (string.IsNullOrEmpty(txtPassword.Text))
    {
        lblMessagePass.Text = "Password field cannot be empty!";
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        passIsValid = false;
    }
    // Making sure that password is at least 6 characters long.
    else if (txtPassword.Text.Length < 6)
    {
        lblMessagePass.Text = "Password field must be at least 6 characters long!";
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        passIsValid = false;
    }
    // Checking for password made of same repeating character.
    // Invalid example: 'aaaaaa'
    else if (!txtPassword.Text.Distinct().Skip(1).Any())
    {
        lblMessagePass.Text = "Password cannot be made of repeating the same characters!";
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        passIsValid = false;
    }
    else
    {
        passIsValid = true;
        lblMessagePass.Text = "Password is valid.";
        lblMessagePass.ForeColor = Color.Green;
    }

    // Making sure that user name and password are not the same.
    // Security measure.
    if (txtUserName.Text == txtPassword.Text)
    {
        lblMessageUser.Text = "User Name and Password can not be the same!";
        lblMessagePass.Text = "User Name and Password can not be the same!";
        lblMessageUser.ForeColor = Color.IndianRed;
        lblMessagePass.ForeColor = Color.IndianRed;
        btnAuthenticate.Enabled = false;
        userIsValid = false;
        passIsValid = false;
    }

    // If all other checks aren't trigered; enable authentication.
    if (passIsValid && userIsValid)
    {
        btnAuthenticate.Enabled = true;
    }
}