Hi All,
I am trying to evaluate GAE + GWT (1.3.2) and I have some issue with
the "detach" feature of JDO-2.0. I have a simple service which return
all questions:
public List<Question> getQuestions() {
PersistenceManager pm = PMF.get().getPersistenceManager();
try {
Query query = pm.newQuery(Question.class);
List<Question> questions =
(List<Question>)pm.detachCopyAll((List<Question>)query.execute());
return questions;
} finally {
pm.close();
}
}
The Question entity is a "Persistent" object which defined with
detachable = "true" and has a bidirectional one to many relationship
to an Answer entity (which defined in the same way.
Unfortunately I started getting the
"IncompatibleRemoteServiceException" from yesterday (till than all
worked well :( ).
I browsed the forums of Google groups and tried to make some changes
to make things working like:
- Implementing from IsSerializable instead of Serializable (on
entities Question & Answer)
- Using "detachCopyAll"
Nothing seems to make a different.
I assume the code will work if I will create DTO for each persistent
entity although I really wish to avoid code duplication, plus that's
missing some of JDO 2.0 nicest feature
Question Code:
--------------------
@PersistenceCapable (detachable = "true")
public class Question implements IsSerializable {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent
private String topic;
@Persistent
private String language;
@Persistent
private String category;
@Persistent
private String experience;
@Persistent
private String difficultLevel;
// Question details
@Persistent
private String title;
@Persistent
private String body;
@Persistent
private String type;
@Persistent
private String image;
@Persistent(mappedBy = "question")
private List<Answer> answers;
// @Persistent
//private Author author;
// Classification properties
public Question(){}
public Question(String topic, String language,
String category, String experience, String
difficultLevel,
String title, String body, String type, String image,
List<Answer> answers) {
super();
//this.author = author;
this.topic = topic;
this.language = language;
this.category = category;
this.experience = experience;
this.difficultLevel = difficultLevel;
this.title = title;
this.body = body;
this.type = type;
this.image = image;
this.answers = answers;
}
public Key getKey() {
return key;
}
public void setKey(Key key) {
this.key = key;
}
// public Author getAuthor() {
// return author;
// }
//
// public void setAuthor(Author author) {
// this.author = author;
// }
public String getTopic() {
return topic;
}
public void setTopic(String topic) {
this.topic = topic;
}
public String getLanguage() {
return language;
}
public void setLanguage(String language) {
this.language = language;
}
public String getCategory() {
return category;
}
public void setCategory(String category) {
this.category = category;
}
public String getExperience() {
return experience;
}
public void setExperience(String experience) {
this.experience = experience;
}
public String getDifficultLevel() {
return difficultLevel;
}
public void setDifficultLevel(String difficultLevel) {
this.difficultLevel = difficultLevel;
}
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public String getBody() {
return body;
}
public void setBody(String body) {
this.body = body;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public String getImage() {
return image;
}
public void setImage(String image) {
this.image = image;
}
public List<Answer> getAnswers() {
return answers;
}
public void setAnswers(List<Answer> answers) {
this.answers = answers;
}
}
Answer Code
------------------
package com.lugo.dao;
import javax.jdo.annotations.IdGeneratorStrategy;
import javax.jdo.annotations.PersistenceCapable;
import javax.jdo.annotations.Persistent;
import javax.jdo.annotations.PrimaryKey;
import com.google.appengine.api.datastore.Key;
import com.google.gwt.user.client.rpc.IsSerializable;
@PersistenceCapable (detachable = "true")
public class Answer implements IsSerializable {
@PrimaryKey
@Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY)
private Key key;
@Persistent
private String answer;
@Persistent
private Boolean isCorrect;
@Persistent
private Question question;
public Answer() {
super();
}
public Answer(String answer, Boolean isCorrect, Question question) {
super();
this.answer = answer;
this.isCorrect = isCorrect;
this.question = question;
}
public Key getKey() {
return key;
}
public void setKey(Key key) {
this.key = key;
}
public String getAnswer() {
return answer;
}
public void setAnswer(String answer) {
this.answer = answer;
}
public Boolean getIsCorrect() {
return isCorrect;
}
public void setIsCorrect(Boolean isCorrect) {
this.isCorrect = isCorrect;
}
public Question getQuestion() {
return question;
}
public void setQuestion(Question question) {
this.question = question;
}
}
All the Best
Luk
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