Question

我有一行代码在加载用户控件时从另一个表单中提取值

usernameconstant.Text = Mainpage.usernameconstantmain.Text

这在正常情况下工作正常，但我需要在同一页面上使用PDF阅读器，当我添加Adobe PDF阅读器时，应用程序完全停止工作，并在上面的代码中给出了这个错误。

System.InvalidOperationException: 'The form referred to itself during construction from a default instance, which led to infinite recursion.  Within the Form's constructor refer to the form using 'Me.''

我尝试删除从另一个页面中提取值的第一行代码，看看它是否真的导致了问题并且错误没有再弹出，但我仍然需要使用PDF阅读器的单独表单中的值并且我不确定为什么这个错误会不断出现。

Public Class Submissioncontrol

Dim conn As New MySqlConnection
Dim Myconnection As String = "server=localhost;user id=root;password=password;database=project"
Dim cmd As New MySqlCommand
Dim da As New MySqlDataAdapter
Dim result As Integer
Dim imgpath As String
Dim arrImage() As Byte
Dim sql As String

Dim connection As MySqlConnection
Dim ride As MySqlCommand


Public Property studentid
Public Property title
Public Property deadline



Private Sub Submissioncontrol_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    usernameconstant.Text = Mainpage.usernameconstantmain.Text

    todaysdate.Text = Today

    Dim number As New Random
    idbox.Text = number.Next(1, 1000000)


End Sub

Private Sub Submit_Click(sender As Object, e As EventArgs)
    connection = New MySqlConnection

    connection.ConnectionString =
    "server=localhost;userid=root;password=aaronwong;database=finalyearproject"
    ' Establishes connection to mysqldatabase '

    Dim reader As MySqlDataReader

    Try
        connection.Open()
        Dim aaasaccess As String
        aaasaccess = "insert into finalyearproject.studentsubmissions (submissionid, studentnumber, time, date, deadline, title, work, modulename) values ('" & idbox.Text & "','" & usernameconstant.Text & "','" & todaystime.Text & "','" & todaysdate.Text & "','" & deadlinesubmission.Text & "','" & titlesubmission.Text & "','" & workload.Text & "','" & modulename.Text & "')"
        ' inserts into specific database schema with the named columns '
        ride = New MySqlCommand(aaasaccess, connection)
        reader = ride.ExecuteReader

        MessageBox.Show("Created")
        connection.Close()

    Catch ex As MySqlException
        MessageBox.Show(ex.Message)
    Finally
        connection.Dispose()
    End Try
End Sub

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
    todaystime.Text = TimeOfDay


End Sub

Private Sub Button2_Click_2(sender As Object, e As EventArgs) Handles Button2.Click


    Try
        conn.ConnectionString = Myconnection
        conn.Open()

        sql = "insert into studentsubmissions(submissionid, studentnumber, time, date, deadline, title, work, modulename) VALUES (@subid, @stunumber, @subtime, @subdate, @workdeadline, @stutitle, @stuwork, @workmodulename)"
        cmd.Connection = conn
        cmd.CommandText = sql




        cmd.Parameters.AddWithValue("@subid", idbox.Text)
        cmd.Parameters.AddWithValue("@stunumber", usernameconstant.Text)
        cmd.Parameters.AddWithValue("@subtime", todaystime.Text)
        cmd.Parameters.AddWithValue("@subdate", todaysdate.Text)
        cmd.Parameters.AddWithValue("@workdeadline", deadlinesubmission.Text)
        cmd.Parameters.AddWithValue("@stutitle", titlesubmission.Text)
        cmd.Parameters.AddWithValue("@stuwork", workload.Text)
        cmd.Parameters.AddWithValue("@workmodulename", modulename.Text)

        cmd.ExecuteNonQuery()

        MessageBox.Show("Created")
        cmd.Parameters.Clear()
        conn.Close()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try


End Sub


End Class



>   Final Year Project.exe!Final_Year_Project.Submissioncontrol.Submissioncontrol_Load(Object sender, System.EventArgs e) Line 30   Basic   Symbols loaded.
[External Code]     Annotated Frame
Final Year Project.exe!Final_Year_Project.Submissioncontrol.New() Line 13   Basic   Symbols loaded.
[External Code]     Annotated Frame
Final Year Project.exe!Final_Year_Project.Submissioncontrol.Submissioncontrol_Load(Object sender, System.EventArgs e) Line 30   Basic   Symbols loaded.
[External Code]     Annotated Frame
Final Year Project.exe!Final_Year_Project.Submissioncontrol.New() Line 13   Basic   Symbols loaded.
[External Code]     Annotated Frame
Final Year Project.exe!Final_Year_Project.Login.Button1_Click(Object sender, System.EventArgs e) Line 33    Basic   Symbols loaded.
[External Code]     Annotated Frame

使用Adobe PDF Reader时应用程序崩溃

0 个答案: