mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-18 14:42:01 -04:00
Mike Bayer
5fb0138a32
Using the approach introduced at https://gist.github.com/zzzeek/6287e28054d3baddc07fa21a7227904e We can now create asyncio endpoints that are then handled in "implicit IO" form within the majority of the Core internals. Then coroutines are re-exposed at the point at which we call into asyncpg methods. Patch includes: * asyncpg dialect * asyncio package * engine, result, ORM session classes * new test fixtures, tests * some work with pep-484 and a short plugin for the pyannotate package, which seems to have so-so results Change-Id: Idbcc0eff72c4cad572914acdd6f40ddb1aef1a7d Fixes: #3414
72 lines
2.2 KiB
Python
72 lines
2.2 KiB
Python
"""Illustrates the asyncio engine / connection interface.
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In this example, we have an async engine created by
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:func:`_engine.create_async_engine`. We then use it using await
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within a coroutine.
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"""
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import asyncio
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from sqlalchemy import Column
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from sqlalchemy import Integer
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from sqlalchemy import MetaData
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from sqlalchemy import String
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from sqlalchemy import Table
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from sqlalchemy.ext.asyncio import create_async_engine
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meta = MetaData()
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t1 = Table(
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"t1", meta, Column("id", Integer, primary_key=True), Column("name", String)
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)
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async def async_main():
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# engine is an instance of AsyncEngine
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engine = create_async_engine(
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"postgresql+asyncpg://scott:tiger@localhost/test", echo=True,
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)
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# conn is an instance of AsyncConnection
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async with engine.begin() as conn:
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# to support SQLAlchemy DDL methods as well as legacy functions, the
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# AsyncConnection.run_sync() awaitable method will pass a "sync"
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# version of the AsyncConnection object to any synchronous method,
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# where synchronous IO calls will be transparently translated for
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# await.
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await conn.run_sync(meta.drop_all)
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await conn.run_sync(meta.create_all)
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# for normal statement execution, a traditional "await execute()"
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# pattern is used.
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await conn.execute(
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t1.insert(), [{"name": "some name 1"}, {"name": "some name 2"}]
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)
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async with engine.connect() as conn:
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# the default result object is the
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# sqlalchemy.engine.Result object
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result = await conn.execute(t1.select())
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# the results are buffered so no await call is necessary
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# for this case.
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print(result.fetchall())
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# for a streaming result that buffers only segments of the
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# result at time, the AsyncConnection.stream() method is used.
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# this returns a sqlalchemy.ext.asyncio.AsyncResult object.
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async_result = await conn.stream(t1.select())
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# this object supports async iteration and awaitable
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# versions of methods like .all(), fetchmany(), etc.
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async for row in async_result:
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print(row)
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asyncio.run(async_main())
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