Calculate
See also: Calculation field
The Behaviour type Calculate executes a Calculation expression that can be used in many ways to evaluate data available in the context of a form or to extract new data from it.
The optional check expression influences whether the actions are executed on 'true' or 'false' by returning a value that can be interpreted as a truthy/falsy value. The input value $input is the output value of the expression above. However, the variable 'orgInput' can also be used to access the original input value of the behaviour ($var(orgInput)).
The Behaviour type Calculate executes a Calculation expression that can be used in many ways to evaluate data available in the context of a form or to extract new data from it.
The return value of the 'calculation' overwrites the original input data ($input) of the behaviour. However, the Calculation expression can refer to input data (e.g. by $input) provided by a Events (Form designer) (e.g. Changed) or from a calling behaviour (see Execute behaviour). The rest of the procedure depends partly on whether an optional Check expression has been configured to determine a Boolean value by another Calculation expression for the selection of the actions (on 'true'/'false') to execute.
Overall, the following cases must be differentiated:
If the Calculation expression contains syntactical errors (e.g. regarding the use of parentheses), the Actions on 'false' will be executed. An error message is assigned as input data ($input). Any Check expression that has been defined is then not evaluated. The original input value of the behaviour can be accessed via the orgInput variable ($var(orgInput))
If no Check expression is defined, then the return value from a syntactically correct Calculation expression ($input) is passed to the Actions on 'true'. This is also the case if the return value is empty ($null), which happens, for example, with a 'division by 0'.
If a Check expression is defined, it is evaluated as a Calculation expression whereby the return value from the already evaluated Calculation expression provides the input data ($input).
If the Check expression contains syntactical errors (e.g. regarding the use of parentheses), the Actions on 'false' will be executed. An error message is assigned as input data ($input).
If the result of the Check expression is not considered false according to the following table, the input data ($input) from the Calculation expression is passed to the Actions on 'true'.
If the result of the Check expression is interpreted as false according to the following table, the input data ($input) from the Calculation expression is passed to the Actions on 'false'.
Data type
Values that are considered false ('falsy'):
(none)
null ($null)
Boolean value
false
Number
0
Text
'', '0', 'false', 'no' (not case sensitive)
Example
A numeric input field (for integers) should determine and display whether the assigned numeric value is even or odd, each time the value is changed.
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Configuration:
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►NOTE◄ Since the number 0 in the Check expression is interpreted as 'false' (see table above), it could be assumed that in this example the Check expression $not($input)would give the same results as $cmp($input,=,0). But this is not the case, because for the function not (Logical negation), every value that is not matching 'true' (case-insensitive) is considered 'false'. However, assigning $input directly as a Check expression and swapping the two Set hint actions would yield appropriate results.