How to use refresh property correctly?

 

We all may know what refreshing an iterator is. It is the process in which an iterator binding rebinds itself to a live row set iterator which is tracking the current row of same data collection.

Having a strong knowledge on ADF Life Cycle might help before reading this article. Please read in the provided link.

Now By default, this happens only once, when the iterator is first accessed by the client layer during the life cycle.

To force the iterator binding to refresh its row set iterator earlier in the lifecyle, you can set the refresh attribute on the iterator binding to a value other than the default.

The refresh and refreshCondition attributes are used to determine when and whether to invoke an executable, such as an iterator binding, or an invokeAction.

Different Values for refresh property              

By default, when JDeveloper adds an executable to a page definition (for example, when you drop an operation as a command component), the refresh attribute for the executable binding is set to deferred.

We can change this into the following values:

·         deffered: It enforces execution whenever the binding is accessed the first time. If no refreshCondition value exists, the executable is invoked. If a value for refreshCondition exists, then that value is evaluated as an EL expression, and if the return value of the evaluation is true, then the executable is invoked

·         prepareModel: It will get refreshed during the Prepare Model phase of ADF life cycle.

·         renderModel: It will get refreshed during the Prepare Render phase of ADF life cycle.

·         ifNeeded: During the Prepare Model and Prepare Render phases, only if needed. For iterators, the refresh is considered needed if the binding has not yet been refreshed. To determine if the execution is needed for an invokeAction, the framework compares the current set of evaluated parameter values with the set that was used to invoke the method action binding previously. If the parameter values for the current invocation are exactly the same as those used previously, the invokeAction does not invoke its bound method action binding.

·         prepareModelIfNeeded & prepareRenderIfNeeded: Same as ifNeeded, except that it is executed during the named phase.

·         never: Not valid for invokeAction executables. For iterators, the iterator will never be refreshed. Use when your own code calls getRowSetIterator() on the iterator binding.

·         always: Not valid for invokeAction executables. For iterators, the iterator will always be refreshed (potentially multiple times) during both the Prepare Model and Prepare Render phases, as well as during the Update Model phase.

·         refreshAfter: Use to handle dependencies between executables. For example, you can set the condition so that this executable refreshes after another executable

Important Note – Distinction Between prepareModel & renderModel

prepareModel comes before JSF’ Invoke application phase.

renderModel comes after JSF’ invoke application phase.

So if you want your iterator to get refreshed after the execution of the action listeners then you should use renderModel.