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import asyncio
import databases
import ormar
import sqlalchemy
from examples import create_drop_database
from pydantic import ValidationError
DATABASE_URL = "sqlite:///test.db"
ormar_base_config = ormar.OrmarConfig(
database=databases.Database(DATABASE_URL),
metadata=sqlalchemy.MetaData(),
)
class Company(ormar.Model):
ormar_config = ormar_base_config.copy(tablename="companies")
id: int = ormar.Integer(primary_key=True)
name: str = ormar.String(max_length=100)
founded: int = ormar.Integer(nullable=True)
class Car(ormar.Model):
ormar_config = ormar_base_config.copy(tablename="cars")
id: int = ormar.Integer(primary_key=True)
manufacturer = ormar.ForeignKey(Company)
name: str = ormar.String(max_length=100)
year: int = ormar.Integer(nullable=True)
gearbox_type: str = ormar.String(max_length=20, nullable=True)
gears: int = ormar.Integer(nullable=True)
aircon_type: str = ormar.String(max_length=20, nullable=True)
@create_drop_database(base_config=ormar_base_config)
async def run_query():
# build some sample data
toyota = await Company.objects.create(name="Toyota", founded=1937)
await Car.objects.create(
manufacturer=toyota,
name="Corolla",
year=2020,
gearbox_type="Manual",
gears=5,
aircon_type="Manual",
)
await Car.objects.create(
manufacturer=toyota,
name="Yaris",
year=2019,
gearbox_type="Manual",
gears=5,
aircon_type="Manual",
)
await Car.objects.create(
manufacturer=toyota,
name="Supreme",
year=2020,
gearbox_type="Auto",
gears=6,
aircon_type="Auto",
)
# select manufacturer but only name,
# to include related models use notation {model_name}__{column}
all_cars = (
await Car.objects.select_related("manufacturer")
.exclude_fields(
["year", "gearbox_type", "gears", "aircon_type", "manufacturer__founded"]
)
.all()
)
for car in all_cars:
# excluded columns will yield None
assert all(
getattr(car, x) is None
for x in ["year", "gearbox_type", "gears", "aircon_type"]
)
# included column on related models will be available,
# pk column is always included
# even if you do not include it in fields list
assert car.manufacturer.name == "Toyota"
# also in the nested related models -
# you cannot exclude pk - it's always auto added
assert car.manufacturer.founded is None
# fields() can be called several times,
# building up the columns to select,
# models selected in select_related
# but with no columns in fields list implies all fields
all_cars = (
await Car.objects.select_related("manufacturer")
.exclude_fields("year")
.exclude_fields(["gear", "gearbox_type"])
.all()
)
# all fiels from company model are selected
assert all_cars[0].manufacturer.name == "Toyota"
assert all_cars[0].manufacturer.founded == 1937
# cannot exclude mandatory model columns -
# manufacturer__name in this example - note usage of dict/set this time
try:
await Car.objects.select_related("manufacturer").exclude_fields(
{"manufacturer": {"name"}}
).all()
except ValidationError:
# will raise pydantic ValidationError as company.name is required
pass
asyncio.run(run_query())
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