Best way of Handling Field Level Validations

For fields to be only numeric of alpha, you better validate on a per-character basis (using the KeyPress event).

For specific field validation (mandatory, minimum length, ...), you better validate in the LostFocus event of each controls.

For referential validation (if FieldA is empty then FieldB must not be empty, ...), you better use form validation (in your save button click event for example).

Using appropriate controls helps you a lot (like a mask edit box, date time picker, ...).

You can roll-your-own textbox controls or use third-party controls to restrict your users' input.  

My saying to my VB students:
"The best validation is the one that requires no code, because the user is limited to entering only valid data."

>>What I had done to handle this is to have a user-control that added a DataType property.  With this, I defined the type of valid data allowed in the field, such as numeric, integer, alpha-only, "sentence", alpha-numeric, e-mail, etc.  When the field is created, define the DataType property and the validation can be done during data entry.<<

If you are interested to create a usercontrol then check out the "PART 2" this link:

http://216.26.168.92/vbworld/file.aspx?tag=activex

It will surely help you to create your own control, without having actually to make validation for each TextBox

-priya

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