| True DataControl 8.0 Reference > Field Object > Field Object Properties > CalcConditionExpression Property |
Condition determining whether the field’s calculated expression should be evaluated.
Field.CalcConditionExpression = variant
Read/Write at run time and design time. Property applies to Field object.
This property specifies the applicability expression for the CalculatedExpression of a field; it determines whether the associated calculated expression should be evaluated.
If this expression is empty or evaluates to True, the calculated expression will be evaluated.
If this expression evaluates to False, the calculated expression will not be evaluated.
The CalcConditionExpression property is generally used with data fields that have a non-empty CalculatedExpression. There is not much sense for a data field to have a non-empty CalculatedExpression and an empty CalcConditionExpression, because then it would be just like a calculated field (sometimes it might be useful though, for storing modified values). CalculatedExpression may be used, for example, to initialize an empty data field with the value of another field that has just been modified. For instance, to initialize the value of the BillTo field with the value of the ShipTo field when the latter has just been entered, you would set the former's CalculatedExpression to ShipTo, and its associated CalcConditionExpression to IsEmpty(BillTo).
See True DataControl Fields for information about data fields and calculated fields. See True DataControl Expressions for general information about expressions.