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Appengine: Check if object is present in database

/ Published in: Java
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import com.google.appengine.api.datastore.Key;\\\\\\\\\\\\\\\\r\\\\\\\\\\\\\\\\nimport com.google.appengine.api.datastore.KeyFactory;

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  1. PersistenceManager pm = JDOHelper.getPersistenceManagerFactory("transactions-optional").getPersistenceManager();
  2. String keyAsString = "key of object";
  3. Key objectDbKey = KeyFactory.createKey(MyDbObject.class.getSimpleName(), keyAsString);
  4. DbObject_Device object = null;
  5. try{
  6. 	object = pm.getObjectById(MyDbObject.class, objectDbKey);
  7. }
  8. if(object != null){
  9. 	// Object was present in database
  10. } else{
  11. 	// .. not present
  12. 	object = new DbObject();
  13. }
  14. // change object values here
  15. pm.makePersistent(object );
  16. pm.close();

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