Bool

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4D v18

Bool


Bool ( expression ) -> Function result

Parameter	Type	Description
expression	Expression	Expression for which to return the boolean form
Function result	Boolean	Boolean form of the expression

Description

The Bool command returns the boolean form of the expression you passed in expression.

The command can return the following values, depending on the expression result type:

Expression result type	Return of the Bool command
Undefined	False
Null	False
Boolean	False if false, otherwise True
Number	False if 0, other True
Other types	False

This command is useful when the code expects a boolean value, and when the evaluation of the expression could result in a different type (e.g. if it evaluates to null or undefined).

Example

You select a value depending on the contents of an object field attribute, anticipating the case where the attribute is missing:

 C_TEXT($married)

 $married:=Choose(Bool([Person]data.married);"Married";"Single")

  //"Single" if the "married" attribute is not found in the field

 ALERT("This person is "+$married)