1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
from db.mongo import Model
from pymongo import ReadPreference
from bson.objectid import ObjectId
from pymongo.read_concern import ReadConcern
from pymongo.write_concern import WriteConcern
class Order(Model):
def __init__(self, user_id, product_id):
self.__id = None
self.__user_id = user_id
self.__product_id = product_id
def store(self):
client = Model.get_client()
my_write_concern_majority = WriteConcern('majority', wtimeout=1000)
def callback(my_session):
product_collection = my_session.client.shoppe.products
user_collection = my_session.client.shoppe.users
# Important:: You must pass the session to the operations.
p = product_collection.find_one({'_id': ObjectId(self.__product_id)}, session=my_session)
u = user_collection.update_one(
{'_id': ObjectId(self.__user_id)},
{"$inc": {"balance": -1 * p["price"]}},
session=my_session)
print(u)
print(p)
pu = product_collection.update_one(
{'_id': ObjectId(self.__product_id)},
{"$inc": {"available": -1}},
session=my_session)
print(pu)
# . Step 2: Start a client session.
with client.start_session() as session:
# Step 3: Use with_transaction to start a transaction, execute the callback, and commit (or abort on error).
session.with_transaction(callback,
read_concern=ReadConcern('local'),
write_concern=my_write_concern_majority,
read_preference=ReadPreference.PRIMARY)
res = Order.get_collection().insert_one(self.to_dict())
return str(res.inserted_id)
@staticmethod
def get_collection():
return Model.get_db().get_collection("orders")
@staticmethod
def dict_to_object(dictionary):
pass
def to_dict(self):
return {
"user_id": self.__user_id,
"product_id": self.__product_id
}