Gets or sets a formula that is evaluated each time that a list item is added or updated.
Assembly: Microsoft.SharePoint (in Microsoft.SharePoint.dll)
The string is too long. The maximum length of a validation formula string is 1024.
Each time that a list item is added or updated, the validation formula is evaluated. If the formula evaluates to false, or if a calculation error occurs, the update is not permitted and the message in the ValidationMessage property is displayed.
Keep in mind that each field in a list item has a ValidationFormula property of its own. The difference is that the validation formula for a field can refer only to that field, whereas the validation formula for a list item can refer to several or even all fields in the item.
Formula validation is independent of the type of validation controlled by the EnforceDataValidation property.