Databases + asyncio.
Project description
Databases
Databases gives you simple asyncio support for a range of databases.
Currently PostgreSQL and MySQL are supported.
Requirements: Python 3.6+
Installation
$ pip install databases
You can install the required database drivers with:
$ pip install databases[postgresql]
$ pip install databases[mysql]
Getting started
Declare your tables using SQLAlchemy:
import sqlalchemy
metadata = sqlalchemy.MetaData()
notes = sqlalchemy.Table(
"notes",
metadata,
sqlalchemy.Column("id", sqlalchemy.Integer, primary_key=True),
sqlalchemy.Column("text", sqlalchemy.String(length=100)),
sqlalchemy.Column("completed", sqlalchemy.Boolean),
)
You can use any of the sqlalchemy column types such as sqlalchemy.JSON, or
custom column types.
Queries
You can now use any SQLAlchemy core queries:
from databases import Database
database = Database('postgresql://localhost/example')
# Establish the connection pool
await database.connect()
# Execute
query = notes.insert()
values = {"text": "example1", "completed": True}
await database.execute(query, values)
# Execute many
query = notes.insert()
values = [
{"text": "example2", "completed": False},
{"text": "example3", "completed": True},
]
await database.execute_many(query, values)
# Fetch multiple rows
query = notes.select()
rows = await database.fetch_all(query)
# Fetch single row
query = notes.select()
row = await database.fetch_one(query)
# Fetch multiple rows without loading everything into memory at once.
query = notes.select()
async for row in database.iterate(query):
...
Transactions
Transactions are managed by async context blocks:
async with database.transaction():
...
For a lower-level transaction API:
transaction = await database.transaction()
try:
...
except:
transaction.rollback()
else:
transaction.commit()
For strict test isolation you will always want to rollback the test database to a clean state between each test case:
async with database.transaction(force_rollback=True):
...
Transaction blocks are managed as task-local state. Nested transactions are fully supported, and are implemented using database savepoints.
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