Hi, all I have a java project on app engine, and I use python based code to backup my datastore.
jdo class------------------------------------------------------------------------ public class PaymentUser { @PrimaryKey private String transId; @Persistent private String media; @Persistent private float fee; @Persistent private String currency; @Persistent private long timestamp; //getters and setter... } The backup python code:--------------------------------------------------------- from google.appengine.ext import db from google.appengine.tools import bulkloader import sys reload(sys) sys.setdefaultencoding('utf-8') class PaymentUser(db.Model): media = db.StringProperty() fee = db.FloatProperty() currency = db.StringProperty() timestamp = db.IntegerProperty() def AddKeys(entity_generator): for entity in entity_generator: entity['key'] = entity.key() yield entity class PaymentUserExporter(bulkloader.Exporter): def __init__(self): bulkloader.Exporter.__init__(self, 'PaymentUser', [('transId', str, None), ('media', str, None), ('fee', str, None), ('currency', str, None), ('timestamp', str, None) ]) def output_entities(self, entity_generator): bulkloader.Exporter.output_entities(self, AddKeys(entity_generator)) exporters = [PaymentUserExporter] class PaymentUserLoader(bulkloader.Loader): def __init__(self): bulkloader.Loader.__init__(self, 'PaymentUser', [('transId', str), ('media', str), ('fee', float), ('currency', str), ('timestamp', int) ]) loaders = [PaymentUserLoader] And I use appcfg to backing up my data to CSV file.problems:-------------------------------------------------- 1.The field currency either some String data or null (not take any space), because I have to backup these strings,so these nulls are.In my CSV file these nulls are str "None". When I upload these data to server again,I found original nulls are replaced by string None.Here I will waste many spaces. 2. The problem is as same as the first one. But is a long property(timestamp), when I upload the data to server These None connot be converted to long value, so there are many exceptions. How can I solve it, Thanks. -- You received this message because you are subscribed to the Google Groups "Google App Engine for Java" group. To post to this group, send email to google-appengine-j...@googlegroups.com. To unsubscribe from this group, send email to google-appengine-java+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/google-appengine-java?hl=en.