Rules allow for dynamic aspects for a form, e.g. by hiding or disabling UI schema elements.
A rule may be attached to any UI schema element and can be defined with the
We'll first look at an example definition of a rule and then explain it in detail.
A rule basically works by first evaluating the
condition property and in case it evaluates to true, executing the associated
effect property determines what should happen to the attached UI schema element once the
condition is met. In the example above, if the
name property has the value of
foo, we'll hide the UI schema element the rule is attached to. Current effects include:
HIDE: hide the UI schema element
SHOW: show the UI schema element
DISABLE: disable the UI schema element
ENABLE: enable the UI schema element
condition property describes what value should be observed and validates that value with against the JSON schema that is specified with
schema. If validation succeeds the condition is fulfilled and the associated
effect will be triggered.
SchemaBasedConditions have been introduced with version 2.0.6 and have become the new default. The previous format via
expectedValue properties is still supported for the time being.