Check if form fields are empty

[Bluenose]

Hello

I have a two-field form (email and password). If I want to check that both fields have been completed by the user, is this likely to work?

strEmail is the ID of the email field and password is the ID of the password field. I don't get any debug errors in Visual Studio 2013 for Web.

Sub Main()

        Dim strEmail As String = Nothing
        Dim password As String = Nothing

        If String.IsNullOrEmpty(strEmail) Then

            MsgBox("Please type in a valid email")

        End If

        If String.IsNullOrEmpty(password) Then

            MsgBox("Please type in a password")

        End If

    End Sub

Thank you.

[Luk3r]

I recreated what you're trying to do with a button (button1) and two textboxes (textbox1 and textbox2). You likely will not want to run two If.. statements because your users will be prompted with unnecessary prompts:

Public Class Form1
    Dim strEmail As String = Nothing
    Dim password As String = Nothing

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        If String.IsNullOrEmpty(strEmail) Then
            MsgBox("Email is empty")
        ElseIf String.IsNullOrEmpty(password) Then
            MsgBox("Password is empty")
        End If
    End Sub

    Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
        strEmail = TextBox1.Text
    End Sub

    Private Sub TextBox2_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox2.TextChanged
        password = TextBox2.Text
    End Sub
End Class

[Bluenose]

Hello Luk3r

Many thanks for your reply and code.

I have put it into Visual Studio (in it's own class, as you have it, in my logon.aspx.vb file) and made a couple of amendments to conform with the name of my button and text-boxes (I couldn't include it in my main class and logon button because I got a few errors).

It looks like this:

Public Class LogonForm


    Dim strEmail As String = Nothing
    Dim password As String = Nothing

        Private Sub LogonBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LogonBtn.Click)

        If String.IsNullOrEmpty(strEmail) Then

            MsgBox("Please type in a valid email")

        ElseIf String.IsNullOrEmpty(password) Then

            MsgBox("Please type in a password")

        End If

    End Sub

    Private Sub strEmail_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strEmail.TextChanged

        strEmail = strEmail.Text

    End Sub

    Private Sub password_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles password.TextChanged

        password = password.Text()

    End Sub

End Class

I have replaced your Button1 with my LogonBtn, your TextBox1.Text with my strEmail.Text, and your TextBox2.Text with my password.Text.

I am getting a few errors, which are almost certainly my fault (please see attachment).

The three 'Handles' errors refer to a 'Handles clause requires a WithEvents variable defined in the containing type or one of its base types' (whatever that means), and the other two errors (blue underlines) here:

strEmail.Text
password.Text()

Error: 'Text is not a member of String'

Thanks again for your time!

[Luk3r]

Bluenose,
These errors come from you having variables and controls named exactly the same. You cannot do this. You would have to do something like the following (notice the button names):

Public Class LogonForm

     Dim strEmail As String = Nothing
     Dim password As String = Nothing
 
     Private Sub LogonBtn_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles LogonBtn.Click)
         If String.IsNullOrEmpty(strEmail) Then
             MsgBox("Please type in a valid email")
         ElseIf String.IsNullOrEmpty(password) Then
             MsgBox("Please type in a password")
         End If
     End Sub
 
     Private Sub strEmailButton_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strEmail.TextChanged
         strEmail = strEmail.Text
     End Sub
 
     Private Sub passwordButton_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles password.TextChanged
         password = password.Text()
     End Sub
 
 End Class

[Bluenose]

Hello Luk3r

Thanks again.

I have copied and pasted your code - thanks - into Visual Studio (VS) and added two buttons to my aspx page:

<asp:Button ID="strEmailButton" runat="server" Text="Button" />

<asp:Button ID="passwordButton" runat="server" Text="Button" />

These are objects, aren't they, like my strEmail text-box, who values we know (their IDs) in a way that we don't know about variables.

I am attaching a screenshot of what VS shows with the code you kindly posted. The errors seems to be the same as before.

Yes, I can see what you mean about confusion and not helped by the error 'Text is not a member of String'.

I get the feeling that the errors shown in the screenshot are not the real errors. For example, there is nothing wrong with:

Handles LogonBtn.Click

because I have used it elsewhere in another class (same aspx.vb file, but another class).

If I were to keep strEmail as the ID of the email form field and declare strEmailValue as the variable, how would that pan out?

How would I set the code out in that case?

Thanks again

[Luk3r]

My apologies, I should have written the code to reflect the name changes. Your code is still trying to set a variable to the name of a textbox that doesn't exist. This code is more accurate:

     Private Sub strEmailButton_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strEmail.TextChanged
          strEmail = strEmailButton.Text
      End Sub
 
      Private Sub passwordButton_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles password.TextChanged
          password = passwordButton.Text
      End Sub

I would venture to guess that the textbox names that I chose are also misleading. They should be something more like "strEmailTextBo x" and "passwordTextBo x" instead of "strEmailButton " and "passwordButton ". That updated code would look like this:

      Private Sub strEmailTextBox_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strEmail.TextChanged
          strEmail = strEmailTextBox.Text
      End Sub
 
      Private Sub passwordTextBox_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles password.TextChanged
          password = passwordTextBox.Text
      End Sub

[Bluenose]

Sorry for the delay in replying.

Please see attachment after I incorporated your code.

I have placed these in my aspx file:

<asp:TextBox ID="strEmailTextBox" runat="server"></asp:TextBox>

<asp:TextBox ID="passwordTextBox" runat="server"></asp:TextBox>

The code looks more self-explanatory but a couple of errors remain. The error I find baffling is this one:

Handles LogonBtn.Click

where LogonBtn is definitely in my aspx file and, indeed, allows me to logon via the code I have in my other class:

 <asp:Button ID="LogonBtn" runat="server" Text="Send" CssClass="submit" OnClick="LogonBtn_Click" />

At the very beginning of your code I have these declarations to make it easier for me to read:

 
Dim strEmailValue As String = Nothing 'variable
Dim passwordValue As String = Nothing 'variable

Dim strEmailTextBox As Object 'TextBox itself
Dim passwordTextBox As Object 'TextBox itself

[Luk3r]

Sorry, I keep assuming that you will notice some of these things yourself and I shouldn't. First things first, you need to modify your subs similar to the below code. Anywhere that "strEmail" or "password" used to be (as a Sub) needs modified to "strEmailTextBo x" and "passwordTextBo x".

Example:

Private Sub strEmailTextBox_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles strEmailTextBox.TextChanged
     strEmail = strEmailTextBox.Text
End Sub

Private Sub passwordTextBox_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles passwordTextBox.TextChanged
    password = passwordTextBox.Text
End Sub