vb.net - 带VB.NET的ASP.NET-Winforms到Web-NullReferenceException字符串拆分/字符串生成器错误

Question

背景:我有一个winForm应用程序，该应用程序根据提供的信息在数据库中注册用户，自动生成随 secret 码和用户名，并通过电子邮件向用户发送链接，以根据所选的营销公司获取应用程序。

问题:

当用户单击“发送邀请”并在除调试中的bundles列表框之外的所有字段上输入了数据时，将抛出NullReferenceException错误，突出显示以下行:Dim MCShort As String = Trim(splitMC(0))

我该如何解决这个问题

这是该网络应用程序的屏幕截图:

这是default.asx.vb的Send_Button_Click方法的代码:

Private Sub Send_Button_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Send_Button.Click

    'TODO Add code to validate that all selections that are reaquired are met.
    'ccemail and the additional message are not required
    Dim firstname As String = txtFirstName.Text
    Dim lastname As String = txtLastName.Text
    Dim ccEmail As String = txtccEmail.Text

    Dim sb As New StringBuilder

    sb.AppendLine("<?xml version=""1.0"" encoding=""utf-8""?>")
    sb.AppendLine("<root>")
    sb.AppendLine("<MarketingCompany>")
    sb.AppendLine("<MarketingCompanyName>")

    ''Get Marketing Company Short Name
    Dim splitMC As String() = Split(marketingCo.SelectedItem, "|")
    Dim MCShort As String = Trim(splitMC(0))
    sb.AppendLine(String.Format("<MCNAme>{0}</MCNAme>", MCShort))


    'sb.AppendLine(String.Format("<MCNAme>{0}</MCNAme>", My.Settings.MarketingCompanyShortName))

    sb.AppendLine(String.Format("<ccEmail>{0}</ccEmail>", txtccEmail.Text))
    sb.AppendLine(String.Format("<emailMessage>{0}</emailMessage>", txtMessage.Text))
    sb.AppendLine(String.Format("<MarketerName>{0}</MarketerName>", txtMarketerName.Text))
    sb.AppendLine("<agent>")
    sb.AppendLine(String.Format("<FirstName>{0}</FirstName>", txtFirstName.Text))
    sb.AppendLine(String.Format("<LastName>{0}</LastName>", txtLastName.Text))
    sb.AppendLine(String.Format("<Email>{0}</Email>", txtEmail.Text))
    sb.AppendLine("<CRMGuid>123456</CRMGuid>")

    Dim spltBundles() As String

    For Each item In bundles.Items
        If Trim(item) <> "" Then
            spltBundles = Split(item, "|")
            sb.AppendLine("<ContractingOpportunity>")
            sb.AppendLine(String.Format("<Carrier>{0}</Carrier>", Trim(spltBundles(0))))
            sb.AppendLine(String.Format("<ContractingOpportunityName>{0}</ContractingOpportunityName>", Trim(spltBundles(1))))
            sb.AppendLine("</ContractingOpportunity>")
        End If
    Next

    sb.AppendLine("</agent>")
    sb.AppendLine("</MarketingCompanyName>")
    sb.AppendLine(" </MarketingCompany>")
    sb.AppendLine(" </root>")
    Dim xmlStr = sb.ToString


    Dim int1 As Boolean = proxy.AddContractOpportunity(xmlStr.ToString, "test", "test")

    MsgBox("aComp Invitation Sent! :)")


End Sub

Answer 1

对于第一个问题，可以对lbCarriers使用OnSelectedIndexChanged事件。

关于提交时缺少数据的问题，应在提交的页面上使用某种形式的验证。 ASP.Net包括a set of validation controls，使工作变得简单。在最简单的级别上，您可以将表单控件设置为必需的，这将允许表单提示用户在触发代码隐藏事件之前填写所有必填字段。