README.md

Demo

This is a showcase project to demonstrate ACS AEM commons error pages together with the SPA editor. In the past this required a lot of hacking, but thanks to recent updates this has become a lot easier and cleaner.

With this approach you can have 404 and 500 pages load in your SPA editor with a proper status. You can then navigate to the homepage or anywhere else on the menubar with React Routing.

In this case we are using React.

Common setup

First, make sure to follow the tutorial in the ACS AEM commons page to install the module. You will still need to put in the JSP files edit the dialog of the root page and obviously create the pages. Also, you will need SPA Page model manager 1.4.0 or higher!

404 Pages

For 404 pages to work, all you need to do is put this in your page template's customheaderlibs.html

<meta property="cq:errorpages" data-sly-test="${inheritedPageProperties.errorPages}" content="${inheritedPageProperties.errorPages}" />

And then use that in our front-end initialization:

const errorPageRoot = PathUtils.getMetaPropertyValue('cq:errorpages') + '/';

ModelManager.initialize({errorPageRoot}).then(pageModel => {
   //... 
});

And that is all to make the 404 pages work.

500 Pages

For 500 pages, we will target server-side generation errors coming from the Sling Model. Any other API-calls or javascript error handling is not covered here. However, you could leverage the ACS AEM commons error page to display an authorable error message.

For the back-end to work we need to do 2 things, 1 set structureDepth to 0 (so we don't load child pages). I haven't found a way to make this work properly with structureDepth not set to 0. Then we just set some dummy code to create an exception.

com.mysite.core.models.PageWithErrorHandling

@Model(adaptables = SlingHttpServletRequest.class, adapters = { Page.class,
        ContainerExporter.class }, resourceType = PageWithErrorHandling.RESOURCE_TYPE)
@Exporter(name = ExporterConstants.SLING_MODEL_EXPORTER_NAME, extensions = ExporterConstants.SLING_MODEL_EXTENSION)
public class PageWithErrorHandling implements Page {

    static final String RESOURCE_TYPE = "mysite/components/page";

    @Self
    @Via(type = ResourceSuperType.class)
    protected Page delegate;

    @Self
    protected SlingHttpServletRequest request;

    @AemObject
    protected com.day.cq.wcm.api.Page resourcePage;

    public Map<String, ? extends ComponentExporter> getExportedItems() {

        if (resourcePage.getName().equals("pagewitherror")) {
            throw new RuntimeException("Let's crash this party!");
        }

        return delegate.getExportedItems();

    }

    //other delegate methods
}

If you want to individually catch component errors, you could try to intercept the ModelFactoryWithError. com.mysite.core.services.ModelFactoryWithError

@Component(service = {ModelFactory.class}, immediate = true,
        property = {
                "sling.filter.scope=request",
                "filter.order=" + Integer.MAX_VALUE
        })
@ServiceRanking(Integer.MAX_VALUE)
public class ModelFactoryWithError implements ModelFactory {

    @Reference(target = ("(component.name=org.apache.sling.models.impl.ModelAdapterFactory)"))
    private ModelFactory modelFactory;

    @Reference
    private ErrorPageHandlerService errorPageHandlerService;

    @Override
    public <T> T getModelFromWrappedRequest(SlingHttpServletRequest slingHttpServletRequest, Resource resource, Class<T> aClass) {
        T model = modelFactory.getModelFromWrappedRequest(slingHttpServletRequest, resource, aClass);

        if (model == null) {

            String errorPage = errorPageHandlerService.findErrorPage(slingHttpServletRequest, slingHttpServletRequest.getResource());
            if (StringUtils.isNotBlank(errorPage)) {

                String errorPagePath = StringUtils.removeEnd(errorPage, ".html");
                Resource errorPageResource = slingHttpServletRequest.getResourceResolver().getResource(errorPagePath);
                Resource errorGridResource = errorPageResource.getChild("jcr:content/root/responsivegrid");

                if (errorGridResource != null) {
                    return (T) modelFactory.getModelFromWrappedRequest(slingHttpServletRequest, errorGridResource, ComponentExporter.class);
                }

            }


        }

        return model;
    }
    
    //other delegate methods
}

Be very careful here, there are potential side effects with this method. What I would recommend, is to perform a resourceType check and catch your own components. You can also create an abstract class that catches the postconstruct method and return some standard error json.