我目前在注册表格中使用MS Captcha。如果表单在一分钟内提交,它就可以完美地工作。但有时,在填写表单后,用户搜索要上传的文档,当他们最终提交表单时,他们得到服务器错误,如下所示:
[NullReferenceException:对象引用未设置为对象。MSCaptcha.CaptchaControl。ValidateCaptcha(字符串userEntry)+ 438
在提交按钮点击,我调用ValidateCaptcha
如下:
Captcha1.ValidateCaptcha(txtCaptcha.Text.Trim());
有人能帮我处理这个异常吗?
如果你没有设置ErrorInputTooFast和ErrorInputTooSlow消息,当CaptchaMaxTimeout时间周期过去时,代码会抛出'NullReferenceException'。
我已经设置了以下属性,以及得到这个工作没有NullReferenceException
ErrorInputTooFast="图像文本输入太快。"errorinputooslow ="图像文本输入太慢。"
我的实现如下,我已经设置CaptchaMaxTimeout为20秒,看看这个问题是否仍然存在。
<uc:CaptchaControl ID="CaptchaUserControl" runat="server" Height="50px" ValidationGroup="PageValidationGroup"
CustomValidatorErrorMessage="The text you entered did not match up with the image provided"
Width="180px" CaptchaLength="5" FontColor="#000000" BackColor="#e6db55" NoiseColor="#26557f"
CaptchaLineNoise="None" CaptchaFontWarping="Low" ImageTag="border='1'" CaptchaBackgroundNoise="Medium"
ErrorInputTooFast="Image text was typed too quickly. " ErrorInputTooSlow="Image text was typed too slowly."
CaptchaMaxTimeout="20" CaptchaMinTimeout="2" EnableViewState="False" />
<asp:TextBox ID="CapthaTextBox" runat="server" MaxLength="10" Width="180px" AutoCompleteType="Disabled"/>
背后的代码 private void AppendValidationErrorMessage( string message)
{
var cv = new CustomValidator();
cv.IsValid = false;
cv.ErrorMessage = message;
cv.ValidationGroup = "PageValidationGroup";
this.Page.Validators.Add(cv);
}
protected void SubmitButtonClick(object sender, EventArgs e)
{
try
{
this.CaptchaUserControl.ValidateCaptcha(CapthaTextBox.Text.GetTrimValue());
if (!this.CaptchaUserControl.UserValidated)
{
this.AppendValidationErrorMessage(this.CaptchaUserControl.CustomValidatorErrorMessage);
}
}
catch (Exception)
{
this.AppendValidationErrorMessage(
"Captcha expired please please reload the page.Note: please copy the data before refreshing data");
}
this.CapthaTextBox.Text = string.Empty;
if (this.Page.IsValid) //&& this.CaptchaUserControl.UserValidated
{
//do something
}
}