jdo

My problem I am porting my application from version 1.x to 2.0 of the DataNucleus plug-in for GAE/J using the new 1.7.5 GAE/J SDK. This changes my JDO version from 2.3 to 3.0.1. My persistent entity class has a primary key of type encoded string, along with read-only access to the object’s numeric ID. Each instance is the sole member of its entity group (children and parent are linked by numeric ID only). Previously, I have been able to create and persist a new MyEntity instance and then immediately access its numeric ID to store in the parent MyEntity instance’s list of child IDs. Now I find

One can easily use JDO syntax to query on multiple parameters as follows: //specify the persistent entity you're querying and you filter usign params query = pm.newQuery(MyClass.class, " customer == paramCustomer && date >= paramStartDate && date <=paramEndDate "); // declare params used above query.declareParameters("com.google.appengine.api.users.User paramCustomer, java.util.Date paramStartDate, java.util.Date paramEndDate"); //pass the object declared as params MyClassList = (List<MyClass>) query.execute(user, startDate, endDate); It's straightforward to programmatically build a string

I have an application deployed in Google app engine. I am getting inconsistent data when i fetch an entity by id immediately after updating that entity. I'm using JDO 3.0 to access the app engine datastore. I have an entity Employee @PersistenceCapable(detachable = "true") public class Employee implements Serializable { /** * */ private static final long serialVersionUID = -8319851654750418424L; @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY, defaultFetchGroup = "true") @Extension(vendorName = "datanucleus", key = "gae.encoded-pk", value = "true") private String id;

I'm trying to setup jdo/jpa in Android Studio and havefollowed an answer from a previous question here . When I attempt to run the enhance task I get: Error:Execution failed for task ':backend:appengineEnhance'. An error occurred enhancing DataNucleus classes. and the log file shows: java.lang.RuntimeException: Unexpected exception at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:76) at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71) at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51) Caused by: java.lang.reflect

I am trying to design a data model which can hold a very large amount of data, does anyone with experience in large volumes of data have any feedback on this, ie: // example only, not meant to compile public class TransactionAccount { private long balance; private List<Transaction> transactions = new ArrayList<Transaction>(); .... public long getBalance() { return balance; } } private class Transaction { public Date date; public long amount; } Based on what I have read, the only way to get transactional integrity on inserting a Transaction and updating balance is to make it one entity group.

Data Access Objects (DAOs) are a common design pattern, and recommended by Sun. But the earliest examples of Java DAOs interacted directly with relational databases -- they were, in essence, doing object-relational mapping (ORM). Nowadays, I see DAOs on top of mature ORM frameworks like JDO and Hibernate, and I wonder if that is really a good idea. I am developing a web service using JDO as the persistence layer, and am considering whether or not to introduce DAOs. I foresee a problem when dealing with a particular class which contains a map of other objects: public class Book { // Book

I got this "javax.jdo.JDOFatalUserException: Error in meta-data for don.Comment.id: Cannot have a java.lang.String primary key and be a child object (owning field is don.Post.comments). NestedThrowables:" when running my grails + app-engine webapp How can I fix this? class Comment.groovy import javax.jdo.annotations.*; @PersistenceCapable(identityType = IdentityType.APPLICATION, detachable="true") class Comment implements Serializable { @PrimaryKey @Persistent(valueStrategy = IdGeneratorStrategy.IDENTITY) String id @Persistent(mappedBy="comments") Post post @Persistent String name @Persistent