QuoteEndpoint.java

package com.mindstorm.famousquotes.entity;

import com.mindstorm.famousquotes.entity.PMF;

import com.google.api.server.spi.config.Api;
import com.google.api.server.spi.config.ApiMethod;
import com.google.api.server.spi.config.ApiNamespace;
import com.google.api.server.spi.response.CollectionResponse;
import com.google.appengine.api.datastore.Cursor;
import com.google.appengine.datanucleus.query.JDOCursorHelper;

import java.util.HashMap;
import java.util.List;

import javax.annotation.Nullable;
import javax.inject.Named;
import javax.persistence.EntityExistsException;
import javax.persistence.EntityNotFoundException;
import javax.jdo.PersistenceManager;
import javax.jdo.Query;

@Api(name = "quoteendpoint", namespace = @ApiNamespace(ownerDomain = "mindstorm.com", ownerName = "mindstorm.com", packagePath = "famousquotes.entity"))
public class QuoteEndpoint {

        /**
         * This method lists all the entities inserted in datastore.
         * It uses HTTP GET method and paging support.
         *
         * @return A CollectionResponse class containing the list of all entities
         * persisted and a cursor to the next page.
         */
        @SuppressWarnings({ "unchecked", "unused" })
        @ApiMethod(name = "listQuote")
        public CollectionResponse<Quote> listQuote(
                        @Nullable @Named("cursor") String cursorString,
                        @Nullable @Named("limit") Integer limit) {

                PersistenceManager mgr = null;
                Cursor cursor = null;
                List<Quote> execute = null;

                try {
                        mgr = getPersistenceManager();
                        Query query = mgr.newQuery(Quote.class);
                        if (cursorString != null && cursorString != "") {
                                cursor = Cursor.fromWebSafeString(cursorString);
                                HashMap<String, Object> extensionMap = new HashMap<String, Object>();
                                extensionMap.put(JDOCursorHelper.CURSOR_EXTENSION, cursor);
                                query.setExtensions(extensionMap);
                        }

                        if (limit != null) {
                                query.setRange(0, limit);
                        }

                        execute = (List<Quote>) query.execute();
                        cursor = JDOCursorHelper.getCursor(execute);
                        if (cursor != null)
                                cursorString = cursor.toWebSafeString();

                        // Tight loop for fetching all entities from datastore and accomodate
                        // for lazy fetch.
                        for (Quote obj : execute)
                                ;
                } finally {
                        mgr.close();
                }

                return CollectionResponse.<Quote> builder().setItems(execute)
                                .setNextPageToken(cursorString).build();
        }

        /**
         * This method gets the entity having primary key id. It uses HTTP GET method.
         *
         * @param id the primary key of the java bean.
         * @return The entity with primary key id.
         */
        @ApiMethod(name = "getQuote")
        public Quote getQuote(@Named("id") Long id) {
                PersistenceManager mgr = getPersistenceManager();
                Quote quote = null;
                try {
                        quote = mgr.getObjectById(Quote.class, id);
                } finally {
                        mgr.close();
                }
                return quote;
        }

        /**
         * This inserts a new entity into App Engine datastore. If the entity already
         * exists in the datastore, an exception is thrown.
         * It uses HTTP POST method.
         *
         * @param quote the entity to be inserted.
         * @return The inserted entity.
         */
        @ApiMethod(name = "insertQuote")
        public Quote insertQuote(Quote quote) {
                PersistenceManager mgr = getPersistenceManager();
                try {
                        if (quote.getId() != null) {
                                if (containsQuote(quote)) {
                                        throw new EntityExistsException("Object already exists");
                                }
                        }
                        mgr.makePersistent(quote);
                } finally {
                        mgr.close();
                }
                return quote;
        }

        /**
         * This method is used for updating an existing entity. If the entity does not
         * exist in the datastore, an exception is thrown.
         * It uses HTTP PUT method.
         *
         * @param quote the entity to be updated.
         * @return The updated entity.
         */
        @ApiMethod(name = "updateQuote")
        public Quote updateQuote(Quote quote) {
                PersistenceManager mgr = getPersistenceManager();
                try {
                        if (!containsQuote(quote)) {
                                throw new EntityNotFoundException("Object does not exist");
                        }
                        mgr.makePersistent(quote);
                } finally {
                        mgr.close();
                }
                return quote;
        }

        /**
         * This method removes the entity with primary key id.
         * It uses HTTP DELETE method.
         *
         * @param id the primary key of the entity to be deleted.
         */
        @ApiMethod(name = "removeQuote")
        public void removeQuote(@Named("id") Long id) {
                PersistenceManager mgr = getPersistenceManager();
                try {
                        Quote quote = mgr.getObjectById(Quote.class, id);
                        mgr.deletePersistent(quote);
                } finally {
                        mgr.close();
                }
        }

        private boolean containsQuote(Quote quote) {
                PersistenceManager mgr = getPersistenceManager();
                boolean contains = true;
                try {
                        mgr.getObjectById(Quote.class, quote.getId());
                } catch (javax.jdo.JDOObjectNotFoundException ex) {
                        contains = false;
                } finally {
                        mgr.close();
                }
                return contains;
        }

        private static PersistenceManager getPersistenceManager() {
                return PMF.get().getPersistenceManager();
        }

}