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
we'll hide the UI schema element the rule is attached to. Current effects
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.