Sub parameter rules control when parameters are visible or hidden. The trigger for a rule is defined by one or more parameters having certain values. A parameter whose visibility is controlled by sub parameter rules is by default hidden and becomes visible once one or more of these rules are triggered.
Definition of trigger and parameters to show/hide
A sub parameter rule contains an optional trigger and one or more parameters whose visibility shall be controlled.
The trigger is defined by first selecting which parameters that shall be included and then for each parameter select the values that shall trigger the rule. In the case of multi choice parameters it's the multi choice values that are selected to participate in the trigger rather than the actual parameters. A sub parameter rule is triggered when all Trigger parameters have been set to one of their triggering values.
See Disallowed combination rules for how triggering values are defined for different types of parameters.
For lookup parameters it's possible to define the non-triggering values instead of the triggering values. This is done by selecting the option Check non-triggering values. Then those values that are not selected are the triggering values and new values that are added to the parameter becomes triggering by default.
The parameters whose visibility shall be controlled by a sub parameter rules are selected in the list of Sub parameters. Selected parameters become visible when the rule's triggering condition is met. If many sub parameter rules or sub parameter expression rules affect the same parameter, it's enough that one of these rules triggering conditions are met for the parameter to become visible.
Parameters that always shall be hidden
By creating a sub parameter rule without a trigger those parameters that are selected as Sub parameters will always be hidden, unless they are made visible by another sub parameter rule or sub parameter expression rule. This can for example be used when introducing new parameters that should not yet be possible to set but are needed for the preparation of other parts of the configuration model like prices, bill 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 meanwhile being hidden in the production site.
Hidden parameters are disabled
A parameter that is hidden via sub parameter rules is also disabled. This means that the parameter is not an effective part of the configuration model, it gets the default value of its data type during execution of expressions and will not get a saved value even if the user had set a value before the parameter was hidden. Notice the difference compared to a parameter on a hidden tab which can still have a value even though the parameter is not visible to the user.
Restoring the value when reappearing
If a parameter that has been set to a value becomes hidden and later is shown again during the same editing session, then the system will try to restore its previous value. However, if this value is no longer allowed due to rules the value of the parameter is cleared out.
