NOTE This is alpha software. All the tests are passing and there is pretty good test coverage but the library is new, new, new. Things may change significantly, there not be a test covering your use case, etc., etc.
Handbag is an embedded database for python. Its goal is to be a viable persistence option for small-to-medium sized projects and also to be enjoyable to use. This is not the DB for giganto-scale applications, but if you want data persistence, consistency and convenience this might be the thing for you.
Handbag uses lmdb (also py-lmdb) so it inherits all of its excellent qualities. When you use Handbag you get:
- Multi-thread and multi-process concurrency
- ACID guarantees
- Pretty good core performance (lmdb benchmark, no handbag benchmarks yet)
- Data validation
- Relationship modeling
- Sorted indexes
The backend system is pluggable making it hypothetically possible to implement other storage mechanisms in the future but as of now, that engine must support multi-table atomic transactions.
import random
from handbag import environment
# Create a database on the filesystem
env = environment.open('/tmp/foos-and-bars.db')
# Define some models that will be stored in the database
class Foo(env.Model):
name = Text(index=True)
flavor = Enum('spicy', 'artichoke', 'red')
indexes = ['name']
class Bar(env.Model):
address = Text()
foo = ManyToOne(Foo, inverse="bars")
# Do everything inside a transaction
with env.write():
foo = Foo(name='Foo Boringface', flavor='spicy')
bar = Bar(address='123 Snapchat Lane', foo=foo)
bar_id = bar.id
# Some time later...
with env.read():
bar = Bar.get(bar_id)
assert bar.address == "123 Snapchat Lane"
assert bar.foo.name == "Foo Boringface"
assert list(foo.bars)[0] == bar
# We can also look up by indexed fields ...
foo2 = Foo.indexes['name'].get("Foo Boringface")
assert foo2 == foo
# Let's add some more foos
with env.write():
for i in range(0,10):
foo = Foo(name="Thing #%d" % i, flavor=random.choice(Foo.flavor.values))
# Indexes also support range lookup
with env.read():
assert Foo.indexes['name'].cursor().range('Th').count() == 10