I have only just started to use ZODB and have been able to use it with
ease so far.
I want to be able to have access to multiple ZODB databases at the same
time that are completely independent.
What I cannot see how to do is to keep the changes to the objects from
each database separate - that is making the transaction commits only
occur for one database at a time even if changes have occurred to
multiple databases between commits.
Can the transactions be made specific to a particular database or
connection?
Below is example code that accesses two independent databases.
It opens the databases, increments the value for an object in each
database, but I only want to commit the changes to one of databases.
The code here commits the changes for both databases.
How do I stop that happening?
I am assuming that I need to do something different than just
transaction.commit() but what do I need to do?
Thanks
Matt
# START CODE
from ZODB import FileStorage, DB
import transaction
from persistent import Persistent
def get_item_root(file_name):
# open the database
storage = FileStorage.FileStorage(file_name)
db = DB(storage)
conn = db.open()
dbroot = conn.root()
return dbroot
def get_item(dbroot, name):
try:
item = dbroot[name]
except KeyError:
item = None
return item
def add_item(dbroot, item):
if item.name not in dbroot:
dbroot[item.name] = item
def save_item(dbroot, item):
transaction.commit()
class Test(Persistent):
def __init__(self, name):
self.name = name
self.value = 0
db_1 = get_item_root(db_1)
db_2 = get_item_root(db_2)
test_1 = get_item(db_1, test_1)
if test_1 is None:
test_1 = Test(test_1)
add_item(db_1, test_1)
test_2 = get_item(db_2, test_2)
if test_2 is None:
test_2 = Test(test_2)
add_item(db_2, test_2)
print BEFORE: test_1: [%s] [%s] % (test_1.name, test_1.value)
print BEFORE: test_2: [%s] [%s] % (test_2.name, test_2.value)
# increment values
test_1.value = test_1.value + 1
test_2.value = test_2.value + 1
print AFTER: test_1: [%s] [%s] % (test_1.name, test_1.value)
print AFTER: test_2: [%s] [%s] % (test_2.name, test_2.value)
save_item(db_1, test_1)
# END CODE #
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