AbstractListing.java

package org.onehippo.forge.weblogdemo.components.overview;

import org.apache.commons.lang.StringUtils;
import org.hippoecm.hst.content.beans.query.HstQuery;
import org.hippoecm.hst.content.beans.query.HstQueryResult;
import org.hippoecm.hst.content.beans.query.exceptions.QueryException;
import org.hippoecm.hst.content.beans.standard.HippoBean;
import org.hippoecm.hst.content.beans.standard.HippoBeanIterator;
import org.hippoecm.hst.content.beans.standard.HippoFolderBean;
import org.hippoecm.hst.core.component.HstComponentException;
import org.hippoecm.hst.core.component.HstRequest;
import org.hippoecm.hst.core.component.HstResponse;
import org.onehippo.forge.weblogdemo.beans.BaseDocument;
import org.onehippo.forge.weblogdemo.beans.BeanConstants;
import org.onehippo.forge.weblogdemo.components.BaseSiteComponent;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.ArrayList;
import java.util.List;

/**
 * Abstract component for an overview of documents in a folder.
 * Queries a folder and puts a paged resultset on the request.
 * Implementing classes should define which document type is used as filter.
 *
 * @author Jasha Joachimsthal
 */
public abstract class AbstractListing extends BaseSiteComponent {
    public static final int PAGESIZE = 10;
    public static final Logger log = LoggerFactory.getLogger(AbstractListing.class);

    @Override
    public void doBeforeRender(HstRequest request, HstResponse response) throws HstComponentException {
        super.doBeforeRender(request, response);
        setPageTitle(request);
        
        HippoBean contentBean = getContentBean(request);
        if (!(contentBean instanceof HippoFolderBean)) {
            log.warn("Parameter hst:relativecontentpath does not reference a folder");
            response.setStatus(HstResponse.SC_NOT_FOUND);
            return;
            // TODO: redirect to 404?
        }

        int page = getPageNumber(request);
        request.setAttribute("page", page);


        request.setAttribute("documents", getDocumentsForOverview(request, page));

    }

    /**
     * Gets a {@link List} of {@link org.hippoecm.hst.content.beans.standard.HippoBean} documents.
     * Can call {@link #getDocumentList(org.hippoecm.hst.core.component.HstRequest, int, Class)} with the specific class to get a List of
     * documents with a specific class under a folder.
     *
     * @param request current {@link org.hippoecm.hst.core.component.HstRequest}
     * @param page    page number within the listing
     * @return {@link java.util.List} of {@link org.hippoecm.hst.content.beans.standard.HippoBean} documents
     */
    protected abstract List<HippoBean> getDocumentsForOverview(HstRequest request, int page);

    protected void setPageTitle(HstRequest request) {
        String pageTitle = getParameter("pageTitle", request) == null ? "" : getParameter("pageTitle", request);
        request.setAttribute("pageTitle", pageTitle);
    }

    /**
     * Gets the current page number for the listing as int with offset 0.
     *
     * @param request current {@link org.hippoecm.hst.core.component.HstRequest}
     * @return int current page number withing a list, offset 0
     */
    private int getPageNumber(HstRequest request) {
        String pageStr = request.getParameter("page");

        int page = 0;
        if (StringUtils.isNotBlank(pageStr)) {
            try {
                page = Integer.parseInt(pageStr);
            } catch (NumberFormatException e) {
                log.debug("Value '{}' cannot be converted to an Integer", pageStr);
            }
        }
        return page;
    }


    private HippoBeanIterator getQueryResultAsIterator(HippoBean contentBean, Class<? extends BaseDocument> beanClass) {
        try {
            HstQuery hstQuery = getQueryManager().createQuery(contentBean, beanClass);
            hstQuery.addOrderByDescending(BeanConstants.PROP_DATE);
            HstQueryResult queryResult = hstQuery.execute();
            return queryResult.getHippoBeans();
        } catch (QueryException e) {
            log.warn("Error in querying blogposts", e);
        }
        return null;
    }


    /**
     * Iterates over query result for the requested "page" and returns a List of documents.
     *
     * @param request   {@link org.hippoecm.hst.core.component.HstRequest}   
     * @param page      current page number
     * @param beanClass the Class of documents that is used as query filter
     * @return {@link java.util.List} of documents or empty List if no documents are found
     */
    protected List<HippoBean> getDocumentList(HstRequest request, int page,
                                              Class<? extends BaseDocument> beanClass) {
        List<HippoBean> documents = new ArrayList<HippoBean>();

        HippoBeanIterator beans = getQueryResultAsIterator(getContentBean(request), beanClass);
        if (beans == null) {
            return documents;
        }

        long beansSize = beans.getSize();
        // calculates the total number of pages
        long pages = beans.getSize() % PAGESIZE > 0L ? beansSize / PAGESIZE + 1L : beansSize / PAGESIZE;

        request.setAttribute("pages", pages);
        if (beansSize > page * ((long) PAGESIZE)) {
            beans.skip(page * PAGESIZE);
        }

        int results = 0;
        while (beans.hasNext() && results < PAGESIZE) {
            HippoBean bean = beans.next();
            if (bean != null) { // document may have been deleted after searching
                documents.add(bean);
                results++;
            }
        }
        return documents;
    }

}