{title:'Lifecycle Hooks', updated:'9.0.0'}

Lifecycle hooks allow you to hook into lifecycle events of the servlet/resource creation and REST calls.

For example, if you want to add an initialization method to your resource:

| @Rest(...) | public class MyResource { | | // Our database. | private Map<Integer,Object> myDatabase; | | @RestHook(INIT) | public void initMyDatabase(RestContext.Builder builder) throws Exception { | myDatabase = new LinkedHashMap<>(); | } | }

Or if you want to intercept REST calls:

| @Rest(...) | public class MyResource { | | // Add a request attribute to all incoming requests. | @RestHook(PRE_CALL) | public void onPreCall(RestRequest req) { | req.setAttribute("foo", "bar"); | } | }

The hook events can be broken down into two categories:

- {@link oajr.annotation.HookEvent}
  - Resource lifecycle events:
    - {@link oajr.annotation.HookEvent#INIT INIT} - Right before initialization.
    - {@link oajr.annotation.HookEvent#POST_INIT POST_INIT} - Right after initialization.
    - {@link oajr.annotation.HookEvent#POST_INIT_CHILD_FIRST POST_INIT_CHILD_FIRST} - Right after initialization, but run child methods first.
    - {@link oajr.annotation.HookEvent#DESTROY DESTROY} - Right before servlet destroy.
  - REST call lifecycle events:
    - {@link oajr.annotation.HookEvent#START_CALL START_CALL} - At the beginning of a REST call.
    - {@link oajr.annotation.HookEvent#PRE_CALL PRE_CALL} - Right before the @RestOp method is invoked.
    - {@link oajr.annotation.HookEvent#POST_CALL POST_CALL} - Right after the @RestOp method is invoked.
    - {@link oajr.annotation.HookEvent#END_CALL END_CALL} - At the end of the REST call after the response has been flushed.

- {@link oajr.annotation.RestHook}