AEM Custom component for page redirect - redirect

Question

I am trying to create a custom component for page redirect. The use case is pageB should be accessible only via pageA. If pageB is accessed directly then user should be redirected to pageA.
In order to achieve this, I am setting a variable in pageA's request scope. In pageB i will be including a component(drag and droppable), which will look for pageA's request scope variable and if it is not available then we pageB will be redirected, using below snippet.
private void redirect(SlingHttpServletRequest request) {
String redirectPath = "/content/geometrixx/home.html";
if (StringUtils.isNotBlank(redirectPath)) {
getResponse().setStatus(HttpServletResponse.SC_MOVED_PERMANENTLY);
getResponse().setHeader(redirectPath);
} else {
LOGGER.error("Redirect path is not set in component");
}
}
But the above code is failing. I believe it is due to "response already committed" error.
Can someone suggest me a way out for this problem?

Answer 1

I would suggest to you to not use a component on a page to do this. There is another mechanism called (Sling) Filter which is much more suited for something like this.
Put simply, a filter is a OSGi service that is called on every request. The filter gets the request and response passed and can use them to do different things, like for example check if a user visited a page before visiting another page.
There is already a good answer for something like this on StackOverflow: Filter request URL before any processing in CQ5.6
Important note:
Filters are only run if a users request gets to AEM. Typical AEM installations use a so called Dispatcher (Apache with a special "Dispatcher" Apache module) that cache responses. If a response is cached the Dispatcher will serve the cached HTML page instead of request AEM. So if a page is served from the Dispatcher cache your filter won't be run and therefore this check can not be done. There are a few ways to work around this but that's a topic for another question.

Answer 2

Sling filter is used when there is a need to handle more than one page following a certain pattern and you want to do some processing beforehand.
If you know the page URL already and simply want a redirect then you can also use sling:Mapping to redirect the page B request to page A.
You can use something like this.
Goto /etc/map/http and create a node below this path. For https requests, create a sling:folder for https as well.
/etc/map
+-- http
| +-- jcr:primaryType="sling:Folder"
+-- page-b
| +-- jcr:primaryType="sling:Mapping"
| +-- sling:redirect=/content/pageA.html -> Type String
| +-- sling:match=localhost.4502/content/pageB(.*)(/.*) -> Type String
+-- https
| +-- jcr:primaryType="sling:Folder"
+-- page-b
| +-- jcr:primaryType="sling:Mapping"
| +-- sling:redirect=/content/pageA.html -> Type String
| +-- sling:match=localhost.4502/content/pageB(.*)(/.*) -> Type String
Or if you simply want an internal handling of the resource and avoid page reload you can use:
jcr:primaryType="sling:Mapping"
sling:internalRedirect=/content/pageA.html -> Type String
sling:match=localhost.4502/content/pageB(.*)(/.*) -> Type String
To handle dispatcher redirect:
Include a rewrite rule in dispatcher for redirection from pageB to pageA.
Note: You can change the regex in sling:match to suit your needs.