It happens to have functional requirement, when specific input field becomes required based on another field value. Sounds clear, however there is one trick you should know while implementing this requirement. First thing ADF developer will try, he will define
AutoSubmit and
PartialTriggers properties between some field and dependent conditionally required field. What happens during runtime, it is not working so straightforward. If we define
PhoneNumber as dependent attribute from
JobId, and implement attribute required condition to be
true when
JobId = AD_PRES:
We will face problem in a case when
PhoneNumber field will be empty. User will try to change
JobId field value to something else, but he will be stuck because framework will report required field validation error:
This happens because there was defined
PartialTrigger dependency between
PhoneNumber and
JobId. Any change in parent attribute triggers child attribute, where validation is invoked and failed for empty value.
Instead of defining
PartialTrigger dependency directly between two fields, we should invoke it through partial trigger dependency in Backing Bean code. Let's define
ValueChangeListener for parent field,
JobId in my case:
Listener code is self explanatory, based on
JobId value, we are setting
PhoneNumber as required or not and then invoking partial target. Its a key difference comparing to
PartialTrigger dependency, now we are changing dependent attribute required property first and only then triggering this attribute refresh. This allows to avoid validation error while changing condition for required property:
It works fine, but you shouldn't forget initial
PhoneNumber correct rendering, there is already predefined expression for required option. This creates trouble, because we are trying to change it from value change listener, ADF_FACES-60058 exception is thrown while changing
JobId:
Its because exists already predefined expression language for
Required property:
Now we will apply old trick from ADF 10g, instead of using expression language, will calculate
Required property value in Backing Bean method:
This method works in the same way as value change listener explained above, only one difference - it always returns
false:
Main trick - you should define this method not directly on
Required property itself, but on unrelated property, let's say -
Readonly. This allows to avoid ADF_FACES-60058 described above. Its why we are returning always
false, because field should be always editable.
On runtime, when
JobId is not AD_PRES,
PhoneNumber is not required:
If we navigate to such record, where
JobId is AD_PRES,
PhoneNumber will be automatically required:
Find employee with
JobId not equal AD_PRES and change it to AD_PRES:
PhoneNumber field will become required:
Now try to change
JobId again, you should be allowed to do the change:
PhoneNumber field will become not required:
