Okay, after a weekend of pain I finally found a solution. I never expected
it, but It's because I used object initializers to create my object. It
seems like the outcome is different and the generated objects are not
persistable...
On Sunday, February 7, 2016 at 4:01:24 PM UTC+1, Adrian Buchmann wrote:
>
> Hi
>
> I'm not sure if it's possible what I'm trying to do. But for our
> application I also have to gather data from a 3rd-party API and I would
> like to persist the to the datastore for caching reasons.
>
> To implement the solution I'm using Eclipse with the App Engine plugin and
> I have created a simple entity like this:
>
> import javax.jdo.annotations.IdentityType;
> import javax.jdo.annotations.PersistenceCapable;
> import javax.jdo.annotations.Persistent;
> import javax.jdo.annotations.PrimaryKey;
>
>
> @PersistenceCapable(identityType = IdentityType.APPLICATION)
> public class Bird {
> @PrimaryKey
> @Persistent
> long id;
> @Persistent
> String name;
> @Persistent
> String germanName;
> @Persistent
> String englishName;
> @Persistent
> String frenchName;
> @Persistent
> String italianName;
>
> public long getId() {
> return id;
> }
> public void setId(long id) {
> this.id = id;
> }
> public String getGermanName() {
> return germanName;
> }
> public void setGermanName(String germanName) {
> this.germanName = germanName;
> }
> public String getEnglishName() {
> return englishName;
> }
> public void setEnglishName(String englishName) {
> this.englishName = englishName;
> }
> public String getFrenchName() {
> return frenchName;
> }
> public void setFrenchName(String frenchName) {
> this.frenchName = frenchName;
> }
> public String getItalianName() {
> return italianName;
> }
> public void setItalianName(String italianName) {
> this.italianName = italianName;
> }
> public String getName() {
> return name;
> }
> public void setName(String name) {
> this.name = name;
> }
> }
>
>
> After that I created an Endpoint with the Eclipse plugin and modified
> listBird slightly (Orange part in the following code), Of course it makes
> no sense at all to do what I'm doing here, but I just want to give you a
> clean example what's my problem. Usually I would call a third party API to
> gather some data to persist there.
>
> package ch.hslu.testproject;
>
> import ch.hslu.testproject.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 = "birdendpoint", namespace = @ApiNamespace(ownerDomain = "
> hslu.ch", ownerName = "hslu.ch", packagePath = "testproject") )
> public class BirdEndpoint {
>
> /**
> * 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 = "listBird")
> public CollectionResponse<Bird> listBird(@Nullable @Named("cursor") String
> cursorString,
> @Nullable @Named("limit") Integer limit) {
>
> PersistenceManager mgr = null;
> Cursor cursor = null;
> List<Bird> execute = null;
>
> try {
> mgr = getPersistenceManager();
> Query query = mgr.newQuery(Bird.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<Bird>) 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 (Bird obj : execute)
> ;
> // CUSTOM
> if(execute.isEmpty()) {
> Bird testBird = new Bird() {{
> englishName = "Test";
> germanName = "Test";
> frenchName = "Test";
> italianName = "Test";
> }};
> mgr.makePersistent(testBird);
> }
> } finally {
> mgr.close();
> }
>
> return CollectionResponse.<Bird>
> 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 = "getBird")
> public Bird getBird(@Named("id") Long id) {
> PersistenceManager mgr = getPersistenceManager();
> Bird bird = null;
> try {
> bird = mgr.getObjectById(Bird.class, id);
> } finally {
> mgr.close();
> }
> return bird;
> }
>
> /**
> * 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 bird the entity to be inserted.
> * @return The inserted entity.
> */
> @ApiMethod(name = "insertBird")
> public Bird insertBird(Bird bird) {
> PersistenceManager mgr = getPersistenceManager();
> try {
> if (containsBird(bird)) {
> throw new EntityExistsException("Object already exists");
> }
> mgr.makePersistent(bird);
> } finally {
> mgr.close();
> }
> return bird;
> }
>
> /**
> * 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 bird the entity to be updated.
> * @return The updated entity.
> */
> @ApiMethod(name = "updateBird")
> public Bird updateBird(Bird bird) {
> PersistenceManager mgr = getPersistenceManager();
> try {
> if (!containsBird(bird)) {
> throw new EntityNotFoundException("Object does not exist");
> ...
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