An simple async ORM with Fastapi in mind.
Project description
ORMar
The ormar
package is an async ORM for Python, with support for Postgres,
MySQL, and SQLite. Ormar is built with:
SQLAlchemy core
for query building.databases
for cross-database async support.pydantic
for data validation.
Because ormar is built on SQLAlchemy core, you can use alembic
to provide
database migrations.
The goal was to create a simple ORM that can be used directly with fastapi
that bases it's data validation on pydantic.
Initial work was inspired by encode/orm
.
The encode package was too simple (i.e. no ability to join two times to the same table) and used typesystem for data checks.
To avoid too high coupling with pydantic and sqlalchemy ormar uses them by composition rather than by inheritance.
ormar is still under development: We recommend pinning any dependencies with ormar~=0.1.1
Note: Use ipython
to try this from the console, since it supports await
.
import databases
import ormar
import sqlalchemy
database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()
class Note(ormar.Model):
__tablename__ = "notes"
__database__ = database
__metadata__ = metadata
# primary keys of type int by dafault are set to autoincrement
id = ormar.Integer(primary_key=True)
text = ormar.String(length=100)
completed = ormar.Boolean(default=False)
# Create the database
engine = sqlalchemy.create_engine(str(database.url))
metadata.create_all(engine)
# .create()
await Note.objects.create(text="Buy the groceries.", completed=False)
await Note.objects.create(text="Call Mum.", completed=True)
await Note.objects.create(text="Send invoices.", completed=True)
# .all()
notes = await Note.objects.all()
# .filter()
notes = await Note.objects.filter(completed=True).all()
# exact, iexact, contains, icontains, lt, lte, gt, gte, in
notes = await Note.objects.filter(text__icontains="mum").all()
# .get()
note = await Note.objects.get(id=1)
# .update()
await note.update(completed=True)
# .delete()
await note.delete()
# 'pk' always refers to the primary key
note = await Note.objects.get(pk=2)
note.pk # 2
Ormar supports loading and filtering across foreign keys...
import databases
import ormar
import sqlalchemy
database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()
class Album(ormar.Model):
__tablename__ = "album"
__metadata__ = metadata
__database__ = database
id = ormar.Integer(primary_key=True)
name = ormar.String(length=100)
class Track(ormar.Model):
__tablename__ = "track"
__metadata__ = metadata
__database__ = database
id = ormar.Integer(primary_key=True)
album = ormar.ForeignKey(Album)
title = ormar.String(length=100)
position = ormar.Integer()
# Create some records to work with.
malibu = await Album.objects.create(name="Malibu")
await Track.objects.create(album=malibu, title="The Bird", position=1)
await Track.objects.create(album=malibu, title="Heart don't stand a chance", position=2)
await Track.objects.create(album=malibu, title="The Waters", position=3)
fantasies = await Album.objects.create(name="Fantasies")
await Track.objects.create(album=fantasies, title="Help I'm Alive", position=1)
await Track.objects.create(album=fantasies, title="Sick Muse", position=2)
# Fetch an instance, without loading a foreign key relationship on it.
track = await Track.objects.get(title="The Bird")
# We have an album instance, but it only has the primary key populated
print(track.album) # Album(id=1) [sparse]
print(track.album.pk) # 1
print(track.album.name) # Raises AttributeError
# Load the relationship from the database
await track.album.load()
assert track.album.name == "Malibu"
# This time, fetch an instance, loading the foreign key relationship.
track = await Track.objects.select_related("album").get(title="The Bird")
assert track.album.name == "Malibu"
# By default you also get a second side of the relation
# constructed as lowercase source model name +'s' (tracks in this case)
# you can also provide custom name with parameter related_name
album = await Album.objects.select_related("tracks").all()
assert len(album.tracks) == 3
# Fetch instances, with a filter across an FK relationship.
tracks = Track.objects.filter(album__name="Fantasies")
assert len(tracks) == 2
# Fetch instances, with a filter and operator across an FK relationship.
tracks = Track.objects.filter(album__name__iexact="fantasies")
assert len(tracks) == 2
# Limit a query
tracks = await Track.objects.limit(1).all()
assert len(tracks) == 1
Data types
The following keyword arguments are supported on all field types.
primary_key
nullable
default
server_default
index
unique
All fields are required unless one of the following is set:
nullable
- Creates a nullable column. Sets the default toNone
.default
- Set a default value for the field.server_default
- Set a default value for the field on server side (like sqlalchemy'sfunc.now()
).primary key
withautoincrement
- When a column is set to primary key and autoincrement is set on this column. Autoincrement is set by default on int primary keys.
Available Model Fields:
String(length)
Text()
Boolean()
Integer()
Float()
Date()
Time()
DateTime()
JSON()
BigInteger()
Decimal(lenght, precision)
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