Raising Errors in a class

[ae_jester]

Hi,

In my form I have a textbox validate routine that calls the individual sets of a class module, which check the data to ensure it is within the field size limits of the database. If the data is too long, I want to raise an error and pass this back to the textbox Validate routine so I can trap the error there. Currently, the program crashes in the Class in the Set properties when the data is too big. How do I pass this error back to the form??? I've included all the code below.

'Here is the text box validate routine on my form 
'Customer is the name of the class object I am using
 
Private Sub txtField_Validate(Index As Integer, Cancel As Boolean)
    On Error GoTo ValidationError
    
    Select Case Index
        Case FirstName
            Customer.FirstName = txtField(FirstName).Text
        Case MI
            Customer.MI = txtField(MI).Text
        Case LastName
            Customer.LastName = txtField(LastName).Text
        Case Spouse
            Customer.Spouse = txtField(Spouse).Text
        Case Address
            Customer.Address = txtField(Address).Text
        Case City
            Customer.City = txtField(City).Text
        Case StateProv
            Customer.StateProv = txtField(StateProv).Text
        Case ZipPostal
            Customer.ZipPostal = txtField(ZipPostal).Text
        Case PhoneNumber1
            Customer.PhoneNumber1 = txtField(PhoneNumber1).Text
        Case PhoneNumber2
            Customer.PhoneNumber2 = txtField(PhoneNumber2).Text
        Case Comments
            Customer.Comments = txtField(Comments).Text
        Case Else
        
    End Select
    
    Exit Sub
    
ValidationError:
    
    MsgBox Err.Number & " " & Err.Description
    txtField(Index).SetFocus
End Sub
 
'Here is an example of a set property in my Customer class
 
Public Property Let FirstName(vData As String)
    If Len(vData) > 20 Then
        Call Err.Raise(vbObjectError + 1, "First name exceeds the maximum length for this field")
    Else
        mFirstName = vData
    End If
End Property

[simondeutsch]

Don't know why you're using the Call function. Using Err.Raise should be fine like this

Err.Raise vbObjectError + 1, "First name exceeds the maximum length for this field"

[kleinma]

if you trap the error in the class using err.raise.. then you can just do something like this

ValidationError:
    
    Select Case Err.Number
        Case 1 + vbObjectError 'this was the error num u made in the class
            MsgBox Err.Description
        Case Else
            'ETC
    End Select
    txtField(Index).SetFocus
End Sub

[kleinma]

Originally posted by simondeutsch
Don't know why you're using the Call function. Using Err.Raise should be fine like this

Err.Raise vbObjectError + 1, "First name exceeds the maximum length for this field"

call can be used or omitted.. it doens't matter.. the only difference it makes is ( ) are required around function/sub params when you use call.. and they can't be used when you don't use call.. unless its returning a value

[ae_jester]

Isn't it 'better coding practice' if the class knows nothing about the interface? I'm trying to write a n-tier demo which I can then use to copy into any new programs I write. I was under the impression that the Business Tier classes should know nothing about the Interface, and the Database Tier classes should know nothing about the Business Tier classes.

Correct me if I'm wrong.

[kleinma]

well i suppose if you just want to display the error you could just show your error description in the error handling.. like

ValidationError:
    MsgBox Err.Description
    txtField(Index).SetFocus
 
End Sub

in this case it would work for you... because you just want to display the error description... in other cases you would need interaction.. because you would need to check specific error numbers and do specific things accordingly.. in that case you would need to look at error numbers

[ae_jester]

Originally posted by kleinma
if you trap the error in the class using err.raise.. then you can just do something like this

ValidationError:
    
    Select Case Err.Number
        Case 1 + vbObjectError 'this was the error num u made in the class
            MsgBox Err.Description
        Case Else
            'ETC
    End Select
    txtField(Index).SetFocus
End Sub

Maybe I'm just confused, or maybe you aren't understanding my problem. I want to be able to trap the error and set the focus to the appropriate text box (from the gui/form!!!) when an error is raised in the class. If this is or is not possible please let me know (I'm sure I've seen this before).

I don't want the class to know which text box to setfocus to, because I want this to be reused with minimal effort in other projects.

Am I making any sense?

[ae_jester]

Nevermind, I looked at your code again and it makes sense now. Thanks again.

[kleinma]

Originally posted by ae_jester
Nevermind, I looked at your code again and it makes sense now. Thanks again.