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Esfand S

Handling very large lists of objects without paging? - Stack Overflow - 0 views

  • I have a class which can contain many small elements in a list. Looks like: public class Farm {    private ArrayList<Horse> mHorses;} just wondering what will happen if the mHorses array grew to something crazy like 15,000 elements. I'm assuming that trying to write and read this from the datastore would be crazy, because I'd get killed on the serialization process. It's important that I can get the entire array in one shot without paging, and each Horse element may only have two string properties in it, so they are pretty lightweight: public class Horse {    private String mId;    private String mName;} I don't need these horses indexed at all. Does it sound reasonable to just store the mHorse array as a raw Text field, and force my clients to do the deserialization? Something like: public class Farm {    private Text mHorsesSerialized;} then whenever the client receives a Farm instance, it has to take the raw string of horses, and split it in order to reinstantiate the list, something like: // GWT client perhapsFarm farm = rpcCall.getMyFarm();String horsesSerialized = farm.getHorses();String[] horseBlocks = horsesSerialized.split(",");for (int i = 0; i < horseBlocks.length; i++) {    // .. continue deserializing the individual objects ...} yeah...
Esfand S

How to upload primary key as an id instead of name - Google App Engine for Java | Googl... - 0 views

  • If you use the RemoteDatastore you have complete control in Java of   what you key is. http://code.google.com/p/remote-datastore/ e.g. this code puts an entity with the id set in your remote datastore   from your local machine:      RemoteDatastore.install();      RemoteDatastore.divert("http://myVersion.latest.myApp.appspot.com/remote-datastore ", "myApp", "myVersion");      DatastoreService service =   DatastoreServiceFactory.getDatastoreService();      Key key = KeyFactory.createKey("MyKindName, 35);      Entity entity1 = new Entity(key);      entity1.setProperty("property1", "hello");      datastore.put(Arrays.asList(entity1, entity2);
Esfand S

How to upload primary key as an id instead of name - Google App Engine for Java | Googl... - 0 views

  • If you use the RemoteDatastore you have complete control in Java of   what you key is. http://code.google.com/p/remote-datastore/ e.g. this code puts an entity with the id set in your remote datastore   from your local machine:      RemoteDatastore.install();      RemoteDatastore.divert("http://myVersion.latest.myApp.appspot.com/remote-datastore ", "myApp", "myVersion");      DatastoreService service =   DatastoreServiceFactory.getDatastoreService();      Key key = KeyFactory.createKey("MyKindName, 35);      Entity entity1 = new Entity(key);      entity1.setProperty("property1", "hello");      datastore.put(Arrays.asList(entity1, entity2);
  • You can do this now using the RemoteDatastore Java utility http://code.google.com/p/remote-datastore/ For example, this code runs on your desktop and creates a single   entity in your live datastore:     // divert datastore operations to live application     RemoteDatastore.install();     RemoteDatastore.divert("http://myVersion.latest.myApp.appspot.com/remote-datastore ", "myApp", "myVersion");     // create an entity with a numeric key     Key key = KeyFactory.createKey("MyKindName, 35);     Entity entity1 = new Entity(key);     entity1.setProperty("property1", "hello");     // put entity to the remote datastore     DatastoreService service =   DatastoreServiceFactory.getDatastoreService();     datastore.put(entity1); This also works for bulk puts
  • this won't be available until 1.3.6. You should be able to do something like this:  - property: __key__    external_name: CityId    export_transform: datastore.Key.id    import_transform: lambda value: datastore.Key.from_path('City', int(value))
Esfand S

Unowned relationship confusion - Google App Engine for Java | Google Groups - 0 views

  • You will only find "unowned relationships" terminology in Google docs. This "unowned relationships" in the GAE/J docs is where you have a field that is a "Key" or a Collection/Map/array of keys. So no *real* relation, just some implicit relation by that "key". You have to manage these keys yourself, and you tie your code to GAE/J by using them.
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