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.
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