185 lines
5.4 KiB
Markdown
185 lines
5.4 KiB
Markdown
# ORM
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<p>
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<a href="https://travis-ci.org/encode/orm">
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<img src="https://travis-ci.com/collerek/async-orm.svg?branch=master" alt="Build Status">
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</a>
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<a href="https://codecov.io/gh/encode/orm">
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<img src="https://codecov.io/gh/collerek/async-orm/branch/master/graph/badge.svg" alt="Coverage">
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</a>
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<a href="https://pypi.org/project/orm/">
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<img src="https://badge.fury.io/py/orm.svg" alt="Package version">
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</a>
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</p>
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The `async-orm` package is an async ORM for Python, with support for Postgres,
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MySQL, and SQLite. ORM is built with:
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* [`SQLAlchemy core`][sqlalchemy-core] for query building.
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* [`databases`][databases] for cross-database async support.
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* [`pydantic`][pydantic] for data validation.
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Because ORM is built on SQLAlchemy core, you can use [`alembic`][alembic] to provide
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database migrations.
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The goal was to create a simple orm that can be used directly with [`fastapi`][fastapi] that bases it's data validation on pydantic.
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Initial work was inspired by [`encode/orm`][encode/orm].
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The encode package was too simple (i.e. no ability to join two times to the same table) and used typesystem for data checks.
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**aysn-orm is still under development: We recommend pinning any dependencies with `async-orm~=0.1`**
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**Note**: Use `ipython` to try this from the console, since it supports `await`.
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```python
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import databases
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import orm
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import sqlalchemy
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database = databases.Database("sqlite:///db.sqlite")
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metadata = sqlalchemy.MetaData()
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class Note(orm.Model):
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__tablename__ = "notes"
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__database__ = database
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__metadata__ = metadata
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id = orm.Integer(primary_key=True)
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text = orm.String(max_length=100)
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completed = orm.Boolean(default=False)
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# Create the database
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engine = sqlalchemy.create_engine(str(database.url))
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metadata.create_all(engine)
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# .create()
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await Note.objects.create(text="Buy the groceries.", completed=False)
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await Note.objects.create(text="Call Mum.", completed=True)
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await Note.objects.create(text="Send invoices.", completed=True)
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# .all()
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notes = await Note.objects.all()
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# .filter()
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notes = await Note.objects.filter(completed=True).all()
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# exact, iexact, contains, icontains, lt, lte, gt, gte, in
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notes = await Note.objects.filter(text__icontains="mum").all()
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# .get()
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note = await Note.objects.get(id=1)
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# .update()
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await note.update(completed=True)
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# .delete()
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await note.delete()
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# 'pk' always refers to the primary key
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note = await Note.objects.get(pk=2)
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note.pk # 2
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```
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ORM supports loading and filtering across foreign keys...
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```python
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import databases
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import orm
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import sqlalchemy
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database = databases.Database("sqlite:///db.sqlite")
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metadata = sqlalchemy.MetaData()
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class Album(orm.Model):
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__tablename__ = "album"
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__metadata__ = metadata
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__database__ = database
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id = orm.Integer(primary_key=True)
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name = orm.String(max_length=100)
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class Track(orm.Model):
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__tablename__ = "track"
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__metadata__ = metadata
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__database__ = database
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id = orm.Integer(primary_key=True)
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album = orm.ForeignKey(Album)
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title = orm.String(max_length=100)
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position = orm.Integer()
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# Create some records to work with.
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malibu = await Album.objects.create(name="Malibu")
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await Track.objects.create(album=malibu, title="The Bird", position=1)
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await Track.objects.create(album=malibu, title="Heart don't stand a chance", position=2)
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await Track.objects.create(album=malibu, title="The Waters", position=3)
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fantasies = await Album.objects.create(name="Fantasies")
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await Track.objects.create(album=fantasies, title="Help I'm Alive", position=1)
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await Track.objects.create(album=fantasies, title="Sick Muse", position=2)
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# Fetch an instance, without loading a foreign key relationship on it.
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track = await Track.objects.get(title="The Bird")
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# We have an album instance, but it only has the primary key populated
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print(track.album) # Album(id=1) [sparse]
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print(track.album.pk) # 1
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print(track.album.name) # Raises AttributeError
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# Load the relationship from the database
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await track.album.load()
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assert track.album.name == "Malibu"
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# This time, fetch an instance, loading the foreign key relationship.
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track = await Track.objects.select_related("album").get(title="The Bird")
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assert track.album.name == "Malibu"
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# Fetch instances, with a filter across an FK relationship.
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tracks = Track.objects.filter(album__name="Fantasies")
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assert len(tracks) == 2
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# Fetch instances, with a filter and operator across an FK relationship.
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tracks = Track.objects.filter(album__name__iexact="fantasies")
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assert len(tracks) == 2
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# Limit a query
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tracks = await Track.objects.limit(1).all()
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assert len(tracks) == 1
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```
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## Data types
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The following keyword arguments are supported on all field types.
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* `primary_key`
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* `allow_null`
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* `default`
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* `index`
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* `unique`
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All fields are required unless one of the following is set:
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* `allow_null` - Creates a nullable column. Sets the default to `None`.
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* `allow_blank` - Allow empty strings to validate. Sets the default to `""`.
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* `default` - Set a default value for the field.
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* `orm.String(max_length)`
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* `orm.Text()`
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* `orm.Boolean()`
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* `orm.Integer()`
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* `orm.Float()`
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* `orm.Date()`
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* `orm.Time()`
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* `orm.DateTime()`
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* `orm.JSON()`
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[sqlalchemy-core]: https://docs.sqlalchemy.org/en/latest/core/
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[databases]: https://github.com/encode/databases
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[pydantic]: https://pydantic-docs.helpmanual.io/
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[encode/orm]: https://github.com/encode/orm/
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[alembic]: https://alembic.sqlalchemy.org/en/latest/
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[fastapi]: https://fastapi.tiangolo.com/ |