Sending requests mannually¶

Send asynchronous SQLite requests manually and adapt to any task.

Introduction¶

The core of the sl3aio library is ConnectionManager and CursorManager classes which wrap the sqlite3’s Conenction and Cursor classes. You can use these classes to work with sqlite databases asynchronously without using the high-level interfaces of the library.

ConnectionManager¶

The ConnectionManager class is build on top of the ConsistentExecutor class, but with an additional methods of sqlite3’s Connection class and singleton pattern for every database accessed using it.

Its use is very similar to the use of the ConsistentExecutor and sending the requests is the same thing as sending them using Connection class. Here is an example:

import asyncio
from sl3aio import Connector

# Replace ... with the desired connection parameters.
cm = Connector('my_database.db', ...).connection_manager()

# Use the context manager
async with cm:
    cursor_manager = await cm.execute('sql query', ['some', 'parameters'])
    async for row in cursor_manager:
        # Some logic with rows...
        pass

    # Do not forget about executemany
    cursor_manager = await cm.executemany(
        'sql query',
        [['some', 'parameters'], ['more', 'parameters'], ...]
    )

# Or start/stop manager mannually
cm.start()
cursor_manager = await cm.executescript('some sql script')
cm.stop()

Hint

The Connector class stores all of the conenction information to stop/start it automatically.

In addition to execution methods there are some other methods from Connection class:

ConnectionManager.commit(): Commits the current transaction.
ConnectionManager.rollback(): Rolls back the current transaction.

You can also get or replace the current connector:

current_connector = cm.connector

# This will stop the manager,
# remove it from the singletons
# if the database path was changed,
# and will start a new manager with the new connector.
cm.set_connector(Connector(...))

To remove the manger from the singletons list use the ConnectionManager.remove() method.

CursorManager¶

The CursorManager class is a wrapepr for the sqlite3’s Cursor class but with support for the asynchronous operations and iterations. You don’t need to start/stop the cursor, because it will stop working automatically with the manager.

First get the CursorManager instance (after executing sql query via the connection manager).

Now you can get the affected rows:

# Iterate over the affected rows
async for row in cursor_manager:
    # Some logic with rows...
    pass

# Fetch one row
row = await cursor_manager.fetchone()
# or
row = await anext(cursor_manager, None)

# Fetch all rows
rows = await cursor_manager.fetch()

# Sliced fetch
# start is optional, default to 0
# stop is optional, default to the length of the result
# step is optional, default to 1
rows = await cursor_manager.fetch(start=..., stop=..., step=...)

Or execute other queries with this cursor:

# Execute SQL query
await cursor_manager.execute('sql query', ['some', 'parameters'])

# Executemany SQL query
await cursor_manager.executemany(
    'sql query',
    [['some', 'parameters'], ['more', 'parameters']]
)

# Execute SQL script
await cursor_manager.executescript('some sql script')