Hi Debal.
Are you trying to find all assets in the DAM and paginate those (and then show their individual metadata) ?
If so, the QueryBuilder API would work just great here. The following creates a new map of the search predicates and adds the path to the dam and the type to "dam:Asset".
Map<String, String> map = new HashMap<String, String>(); map.put("path", "/content/dam"); map.put("type", "dam:Asset");The next part will handle the pagination for you:
map.put("p.offset", 0); map.put("p.limit", 20);where the offset is the start of the resulting collection of asset and the limit it how many assets the result should contain. If we want to show 20 assets one each page we simply put the limit to 20. And for the first page we want the offset to be 0.
Then we do the search with the following code and put our result in the SearchResult named result:
Query query = builder.createQuery(PredicateGroup.create(map), session); SearchResult result = query.getResult();
After that we want to extract some metadata from our search. Why ? Well we want to see how many total results we had and how many pages it would take to display them all given the number of results we wanted to show on each page. This is all done by using the handy build in methods of the SearchResult. We put the total in the variable totalMatches and the numberOfPages with the following code:
// paging metadata int hitsPerPage = result.getHits().size(); // 20 (set above) or lower long totalMatches = result.getTotalMatches(); long offset = result.getStartIndex(); long numberOfPages = totalMatches / 20;
In the last step we want to iterate over our results and display the asset information (the metadata). This can be done with the following code:
for (Hit hit : result.getHits()) { //Something in the lines of... Asset damAsset = hit.getResource().adaptTo(Asset.class); Map<String, Object> metadata = damAsset.getMetadata(); String displayTitle = "No title" if(metadata.containsKey("dc:title")){ Object titleObject = metadata.get("dc:title"); if (titleObject instanceof Object[]) { Object[] titleArray = (Object[]) titleObject; displayTitle = (titleArray.length > 0) ? titleArray[0].toString() : displayTitle; } else { displayTitle = titleObject.toString(); } } logger.info("Asset title:" + displayTitle); }Here we iterate over all the results and then adapt each hit to an asset from which we can retrieve it's metadata.
Then we log this one to the log :) Of course you will do something different with this :)
In the last step we want to handle the pagination this is done by using some other great built in features. It could look like this:
<% pageContext.setAttribute("result", result); %> <ul> <li> <a href="${currentPage.path}.${result.previousPage.index}.html">Previous</a> </li> <c:forEach var="page" items="{result.resultPages}"> <c:choose> <c:when test="${page.currentPage}"> <li><a href="">${page.index + 1}</a></li> </c:when> <c:otherwise> <li> <a href="${currentPage.path}.${page.index}.html">${page.index + 1}</a> </li> </c:otherwise> </c:choose> </c:forEach> <li> <a href="${currentPage.path}.${result.nextPage.index}.html">Next</a> </li> </ul>And that would be a quick version of implementing pagination and asset metadata extraction together.
Once you see that this works, and of course handled the different query parameters sent to the page that you are on you could start to extract most of this into you own custom tag library.
There are a lot of great guides on that around. For more info about the querybuilder API take a look at this page: http://dev.day.com/docs/en/cq/current/dam/customizing_and_extendingcq5dam/query_builder.html
Good Luck
/Johan
