I want to validate empty textbox, it works but it gives error when at Convert.ToInt32(student.Text) as Input String is not in correct format. Please help me how to validate.

Question

1.00/5 (1 vote)

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VB.NET

Public Sub CheckEmptyTextbox(ByVal groupbox As GroupBox)
       Dim txt As Control
       For Each txt In groupbox.Controls
       If TypeOf txt Is TextBox Then
           If txt.Text = "" Then
               MsgBox("Fill Details To Proceed",MsgBoxStyle.Exclamation)
               Exit For
           End If
           End If
       Next
   End Sub

----------------------------------------------------------------------------------

C#

CheckEmptyTextbox(GroupBox1)
        'Dim con As New SqlConnection("Data Source=ASHUTOSH-PC\SQLEXPRESS;Initial Catalog=Art Station Management System;Integrated Security=True")
        Dim com As SqlCommand
        Dim com1 As New SqlCommand
        Dim str As String
        Dim str1 As String
        Dim i = Convert.ToInt32(stuidcmb.Text)
        Dim a = Convert.ToInt32(stuagetxt.Text)
        Dim gender As String = String.Empty
        If stumalerd.Checked Then
            gender = "Male"
        ElseIf stufemalerd.Checked Then
            gender = "Female"
        End If
        ' Try
        con.Open()
        str = "Insert into StudentRegister values (@sstudentid,@sname,@smiddlename,@ssurname,@sdob,@ccoursename,@btbatchid,@sage,@sgender,@scontact,@saddress,@semailid,@sdatereg)"
        com = New SqlCommand(str, con)
        com.Parameters.AddWithValue("@sstudentid", i)
        com.Parameters.AddWithValue("@sname", stufnametxt.Text)
        com.Parameters.AddWithValue("@smiddlename", stumnametxt.Text)
        com.Parameters.AddWithValue("@ssurname", stulnametxt.Text)
        com.Parameters.AddWithValue("@sdob", DateTimePicker2.Value.Date)
        com.Parameters.AddWithValue("@ccoursename", coursenamecmb.Text)
        com.Parameters.AddWithValue("@btbatchid", batchidcmb.Text)
        com.Parameters.AddWithValue("@sage", a)
        com.Parameters.AddWithValue("@sgender", gender)
        com.Parameters.AddWithValue("@scontact", stucntcttxt.Text)
        com.Parameters.AddWithValue("@saddress", stuaddtxt.Text)
        com.Parameters.AddWithValue("@semailid", stuemailtxt.Text)
        com.Parameters.AddWithValue("@sdatereg", DateTimePicker1.Value.Date)
        com.CommandText = str
        com.ExecuteNonQuery()
        con.Close()

        con.Open()
        str1 = "Insert into AttendanceStudent values (@sstudentid,@sname,@btbatchid,@ccoursename,@atsdate,'ABSENT')"
        com1 = New SqlCommand(str1, con)
        com1.Parameters.AddWithValue("@sstudentid", i)
        com1.Parameters.AddWithValue("@sname", stufnametxt.Text)
        com1.Parameters.AddWithValue("@btbatchid", batchidcmb.Text)
        com1.Parameters.AddWithValue("@ccoursename", coursenamecmb.Text)
        com1.Parameters.AddWithValue("@atsdate", DateTimePicker1.Value.Date)
        com1.CommandText = str1
        com1.ExecuteNonQuery()
        con.Close()
        MsgBox("Record Inserted Successfully", MsgBoxStyle.Information)
        Display()
        clear()
        'Catch ex As Exception

        'End Try

Posted 9-Jan-16 7:31am

Ashutosh Dutondkar

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Wendelius · Accepted Answer · 2016-01-09T07:39:00

Solution 1

As far as I can see you check if the text boxes are empty but you don't exit from the calling method if validation fails.

In other words the validation should be something like

VB

Public Function CheckEmptyTextbox(ByVal groupbox As GroupBox) As Boolean
       Dim txt As Control
       For Each txt In groupbox.Controls
       If TypeOf txt Is TextBox Then
           If txt.Text = "" Then
               MsgBox("Fill Details To Proceed",MsgBoxStyle.Exclamation)
               CheckEmptyTextbox = False ' Set the return value to false
               Exit Function ' exit validation and return false
           End If
           End If
       Next
       CheckEmptyTextbox = True ' everything good, return true
   End Function

And when calling

VB

...
        If Not CheckEmptyTextbox(GroupBox1) Then
           Exit Sub  ' if validation failed, do not continue forward
        End If
        Dim con As New SqlConnection("Data Source=ASHUTOSH-PC\SQLEXPRESS;Initial Catalog=Art Station Management System;Integrated Security=True")
...

Posted 9-Jan-16 7:39am

Wendelius

Updated 9-Jan-16 7:40am

v2

Comments

Thomas Daniels 9-Jan-16 13:42pm

+5!

Wendelius 9-Jan-16 15:07pm

Thank you :)

Ashutosh Dutondkar 9-Jan-16 15:11pm

Thank you so much! Now its not giving me an error! Thank you very much! +10! :);)

Wendelius 9-Jan-16 15:16pm

You're most welcome :)

Ashutosh Dutondkar 9-Jan-16 15:33pm

If Not CheckEmptyTextbox(GroupBox1) Then
Exit Sub
End If
'Dim con As New SqlConnection("Data Source=ASHUTOSH-PC\SQLEXPRESS;Initial Catalog=Art Station Management System;Integrated Security=True")
Dim com As SqlCommand
Dim com1 As New SqlCommand
Dim str As String
Dim str1 As String
Dim i = Convert.ToInt32(stuidcmb.Text)
Dim a = Convert.ToInt32(stuagetxt.Text)
Dim gender As String = String.Empty
If stumalerd.Checked Then
gender = "Male"
ElseIf stufemalerd.Checked Then
gender = "Female"
End If
' Try
con.Open()
str = "Insert into StudentRegister values (@sstudentid,@sname,@smiddlename,@ssurname,@sdob,@ccoursename,@btbatchid,@sage,@sgender,@scontact,@saddress,@semailid,@sdatereg)"
com = New SqlCommand(str, con)
com.Parameters.AddWithValue("@sstudentid", i)
com.Parameters.AddWithValue("@sname", stufnametxt.Text)
com.Parameters.AddWithValue("@smiddlename", stumnametxt.Text)
com.Parameters.AddWithValue("@ssurname", stulnametxt.Text)
com.Parameters.AddWithValue("@sdob", DateTimePicker2.Value.Date)
com.Parameters.AddWithValue("@ccoursename", coursenamecmb.Text)
com.Parameters.AddWithValue("@btbatchid", batchidcmb.Text)
com.Parameters.AddWithValue("@sage", a)
com.Parameters.AddWithValue("@sgender", gender)
com.Parameters.AddWithValue("@scontact", stucntcttxt.Text)
com.Parameters.AddWithValue("@saddress", stuaddtxt.Text)
com.Parameters.AddWithValue("@semailid", stuemailtxt.Text)
com.Parameters.AddWithValue("@sdatereg", DateTimePicker1.Value.Date)
com.CommandText = str
com.ExecuteNonQuery()
con.Close()
If stucntcttxt.Text.Length <> 10 Then
MsgBox("Contact Number Must Be 10 Characters Long", MsgBoxStyle.Information)
Exit Sub
End If

If EmailAddressCheck(stuemailtxt.Text) = True Then
MsgBox("Please enter your email address correctly", vbInformation)
stuemailtxt.Text = ""
Exit Sub
End If

con.Open()
str1 = "Insert into AttendanceStudent values (@sstudentid,@sname,@btbatchid,@ccoursename,@atsdate,'ABSENT')"
com1 = New SqlCommand(str1, con)
com1.Parameters.AddWithValue("@sstudentid", i)
com1.Parameters.AddWithValue("@sname", stufnametxt.Text)
com1.Parameters.AddWithValue("@btbatchid", batchidcmb.Text)
com1.Parameters.AddWithValue("@ccoursename", coursenamecmb.Text)
com1.Parameters.AddWithValue("@atsdate", DateTimePicker1.Value.Date)
com1.CommandText = str1
com1.ExecuteNonQuery()
con.Close()
MsgBox("Record Inserted Successfully", MsgBoxStyle.Information)
Display()
clear()
'Catch ex As Exception

'End Try
End Sub

Ashutosh Dutondkar 9-Jan-16 15:36pm

One more doubt! M checking validate fields! like contact number , age, email etc. So, if i entered wrong data and click insert button it is validating me but the problem is after correcting the field the data is getting inserted 2 times because i have press insert 2 times! As many time if i will press insert button because of validation that many times the data is getting inserted

Wendelius 9-Jan-16 15:42pm

The main problem is that you do validations after inserts. Move all the validations into the beginning of the sub and if they all succeed do the inserts after that.

Another problem is that you're not using transactions for multiple statements. I suggest reading Properly executing database operations[^]

Ashutosh Dutondkar 10-Jan-16 14:04pm

thanks it helped me again! :) Now the validation are working properly!

Wendelius 10-Jan-16 14:19pm

That's great to hear :)

Ashutosh Dutondkar 11-Jan-16 13:29pm

One more thing please! I have datagirdview in my WinForms and in which i have checkbox column, and other two columns with service name and total. When i will check the check box in gird view i want to display the service name and total in the next forms listbox on click of 'OK' button! M not getting how to do it, please help me with it!

Wendelius 15-Jan-16 1:19am

Since this is a different issue I suggest posting a new question if you haven't already done so. This way you'll get opinions and solutions from several persons.