vb.net If Else statement - vb.net

Question

I have this if else statement that I need help with.
What I would like to happen is the user enters a number in data grid view columnIndex 0. If the first validation (If CheckSatus(chkValue)) fails turn the back color red and stop. If its valid I want to continue to CheckRelease(chkValue). Right now if its invalid it goes to CheckRelease(chkValue) and change the back color yellow.
Current Code:
Private Sub gridUserEntries_CellLeave(sender As Object, e As DataGridViewCellEventArgs) Handles gridUserEntries.CellLeave
'Validate Release Number is validate and that Release is in F4 screen
If (e.ColumnIndex = 0) Then
Dim currCell As DataGridViewCell = gridUserEntries.CurrentCell
Dim chkValue As String = currCell.GetEditedFormattedValue(currCell.RowIndex, DataGridViewDataErrorContexts.Display)
If Not (chkValue.Trim = "") Then
'Validate if release is in jobscopedb.IPJOBM table
If CheckSatus(chkValue) Then
currCell.Style.BackColor = Color.White
Else
currCell.Style.BackColor = Color.Red
btnUpdatePPUSRFS.Enabled = False
btnClear.Enabled = True
End If
'Validate if the Release Number is in the PPUSRFS TABLE
If CheckRelease(chkValue) Then
currCell.Style.BackColor = Color.White
btnValidate.Enabled = True
btnRetrieve.Enabled = True
btnClear.Enabled = True
Else
currCell.Style.BackColor = Color.Yellow
btnInsertPPUSRFS.Enabled = True
btnValidate.Enabled = False
btnRetrieve.Enabled = False
End If
Else
currCell.Style.BackColor = Color.White
End If
End If

Answer 1

Simplify each test by only looking for the failure condition (no Else block), and then use a Return statement to stop processing. Then put the success code just once, after all the tests:
If (e.ColumnIndex = 0) Then
Dim currCell As DataGridViewCell = gridUserEntries.CurrentCell
Dim chkValue As String = currCell.GetEditedFormattedValue(currCell.RowIndex, DataGridViewDataErrorContexts.Display)
'Validate if release is in jobscopedb.IPJOBM table
If String.IsNullOrWhitespace(chkValue) Then
currCell.Style.BackColor = Color.Red
btnUpdatePPUSRFS.Enabled = False
btnClear.Enabled = True
Return ' or Exit Sub
End If
'Validate if the Release Number is in the PPUSRFS TABLE
If Not CheckRelease(chkValue) Then
currCell.Style.BackColor = Color.Yellow
btnInsertPPUSRFS.Enabled = True
btnValidate.Enabled = False
btnRetrieve.Enabled = False
Return
End If
' Add as many other tests as you need
'Made it this far means success
currCell.Style.BackColor = Color.White
btnValidate.Enabled = True
btnRetrieve.Enabled = True
btnClear.Enabled = True
End If
Even better, use a boolean so you also only need the failure code once:
If (e.ColumnIndex = 0) Then
Dim currCell As DataGridViewCell = gridUserEntries.CurrentCell
Dim chkValue As String = currCell.GetEditedFormattedValue(currCell.RowIndex, DataGridViewDataErrorContexts.Display)
'Validate if release is in jobscopedb.IPJOBM table
Dim Success As Boolean = Not String.IsNullOrWhitespace(chkValue)
'Validate if the Release Number is in the PPUSRFS TABLE
Success = Success AndAlso CheckRelease(chkValue)
' Add as many other tests as you need
If Success Then
currCell.Style.BackColor = Color.White
btnValidate.Enabled = True
btnRetrieve.Enabled = True
btnClear.Enabled = True
Else
currCell.Style.BackColor = Color.Yellow
btnInsertPPUSRFS.Enabled = True
btnValidate.Enabled = False
btnRetrieve.Enabled = False
End If
End If
Note the use of AndAlso, which short-circuits, meaning it will stop evaluating the expression as soon as it knows that logical result (when the first part is False). The CheckRelease() only runs if Success is True. We can use this to further reduce the code:
Dim Success As Boolean =
Not String.IsNullOrWhitespace(chkValue) AndAlso
CheckRelease(chkValue) AndAlso
SomeOtherTest() AndAlso
AsManyAsYouNeed()