Inclusion expression rules determine whether a parameter is an active part of the configuration model or not. These rules work like inclusion rules, with the difference that the trigger is a Boolean expression, allowing for more complex logic. When a parameter is excluded by these rules, it is automatically hidden from the user interface and disabled in the background.
Definition of trigger and parameters to include
An inclusion expression rule contains a trigger and one or more parameters whose inclusion is controlled by the rule.
The trigger expression is a Boolean formula, and the rule is triggered as long as the expression evaluates to true. An empty trigger expression is treated as always true.
The parameters whose inclusion is controlled by an inclusion expression rule are selected in the Inclusion parameters list. Selected parameters become active and visible when the rule's triggering condition is met. If multiple inclusion rules or inclusion expression rules affect the same parameter, it is sufficient for just one of these rules' triggering conditions to be met for the parameter to be included.
Parameters that always shall be hidden
By creating an inclusion expression rule with false as the trigger expression, the parameters selected as inclusion parameters will always be excluded, unless they are made active by another inclusion rule or inclusion expression rule. This can be used, for example, when introducing new parameters that should not yet be available to set, but are required to prepare other parts of the configuration model, such as prices, bills of materials, or visualizations. By also setting the site effectivity for the rule, the new parameters can be made available for testing in the administration site while remaining excluded in the production site.
Excluded parameters are disabled
A parameter that is excluded via inclusion expression rules is also disabled. This means that the parameter is not an active part of the configuration model.
To prevent errors when the system evaluates expressions elsewhere—such as in bills of materials (BOM), reports, or graphics—the excluded parameter must still provide a value. Therefore, it automatically receives the default value of its data type during expression execution.
Additionally, the parameter will not retain any saved value; even if the user had manually set a value before the parameter became excluded, that value is discarded. Note the difference compared to a parameter on a hidden tab, which is still included in the model and can hold its value even though it is invisible to the user.
Restoring values upon reappearing
If a parameter that has been assigned a value becomes excluded and is later included again during the same editing session, the system will attempt to restore its previous value. However, if this value is no longer allowed due to other rules, the parameter value is cleared.
