[COMPONENT] CQ filter

Sling Request Invocation Chain

  

Implementing Sling Filters

Registration of Filters

1. Standard Servlet Filter (javax.servlet.Filter)
1. Need to be registered as Service („manually“ or SlingFilter SCR Annotation)
2. Order and FilterScopes can be defined
3. Order defined by Serviceranking
4. Filterscopes
1. REQUEST
2. COMPONENT
3. ERROR
4. INCLUDE *
5. FORWARD *

* FilterChain executes COMPONENT scope for these scopes as well.

SCR Annotation

@SlingFilter(scope = SlingFilterScope.COMPONENT, order = -10000, metatype = false) public class MyComponentFilter implements javax.servlet.Filter { @Override public void doFilter(ServletRequest pRequest, ServletResponse pResponse, FilterChain pChain) throws IOException, ServletException { // Implement Filter // continue with filter chaining pChain.doFilter(pRequest, pResponse); } }

Filter Order

Existing Filters might use the deprecated “filter.order” instead “service.ranking”.

Existing Filters and their execution ORDER can be inspected via http://<instance>:<port>/system/console/status-slingfilter

Check Filterconditions at first place

public void doFilter(ServletRequest pRequest, ServletResponse pResponse, FilterChain pChain) throws IOException, ServletException { if (!(pRequest instanceof SlingHttpServletRequest)) { throw new ServletException("Request is not a Sling HTTP request."); } if (isFilterEnabled(slingRequest)) { // Implement Filter-Logic } else { // continue with filter chaining pChain.doFilter(pRequest, pResponse); } }

Check available Information from slingRequest if Filter should do anything.

Be aware that these checks may be performed a lot especially for COMPONENT scope

Accessing and Using Data in Filter

if (isFilterEnabled(slingRequest)) { if (isFilterEnabled(slingRequest)) { Resource resource = slingRequest.getResource(); // already resolved if (null != resource) { PrintWriter writer = pResponse.getWriter(); writer.write("<component resourceType=\"" + resource.getResourceType() + "\">"); pChain.doFilter(pRequest, pResponse); writer.write("</component>"); return; } } }