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Migrate from pydantic 2.XX to 0.20.0

Version 0.20.0 provides support for pydantic v2.XX, provides significant speed improvements for developers (validation and serialization are written in rust) and cleaner APIs, while it drops support for pydantic v.1.XX.

significant change

Migrating to version>= 0.20.0 requires several changes to work correctly.

Omar Model Configuration

Each ormar model now requires an ormar_config parameter that is an instance of the OrmarConfig class, not a Meta class definition. Note that the attribute must be named ormar_config and an instance of the config class.

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import databases
import ormar
import sqlalchemy

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

# ormar < 0.20
class Album(ormar.Model):
    class Meta:
        database = database
        metadata = metadata
        tablename = "albums"


    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    favorite: bool = ormar.Boolean(default=False)

# ormar >= 0.20
class AlbumV20(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
        tablename="albums_v20"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    favorite: bool = ormar.Boolean(default=False)

OrmarConfig api/Parameters

ormar_config exposes the same set of settings as the Meta class provides. This means that you can initialize the configuration with any of the following parameters:

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metadata: Optional[sqlalchemy.MetaData]
database: Optional[databases.Database]
engine: Optional[sqlalchemy.engine.Engine]
tablename: Optional[str]
order_by: Optional[List[str]]
abstract: bool
exclude_parent_fields: Optional[List[str]]
queryset_class: Type[QuerySet]
extra: Extra
constraints: Optional[List[ColumnCollectionConstraint]]

BaseMeta Equivalents-Best Practices

Note that to reduce code duplication and simplify development, it is still recommended to create a base configuration and provide a copy for each model. OrmarConfig provides a convenient way to copy for this.

The copy method accepts the same parameters as OrmarConfig init, so you can override them as needed, but by default it returns properties that already exist, except for tablename, order_by, and constraints, which are cleared by default.

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import databases
import ormar
import sqlalchemy

base_ormar_config = ormar.OrmarConfig(
    database=databases.Database("sqlite:///db.sqlite"),
    metadata=sqlalchemy.MetaData()
)

class AlbumV20(ormar.Model):
    ormar_config = base_ormar_config.copy(
        tablename="albums_v20"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)


class TrackV20(ormar.Model):
    ormar_config = base_ormar_config.copy(
        tablename="tracks_v20"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)

The options field parameter is no longer supported.

Prior to version 0.20, you could provide option parameters to any existing ormar field to limit the acceptable values. This feature has been removed and you should use the ormar.Enum field designed for this purpose. If you want to preserve database field types (i.e. integer fields), you can always write custom validators.

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import databases
import ormar
import sqlalchemy

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

# ormar < 0.20
class Artist(ormar.Model):
    class Meta:
        database = database
        metadata = metadata


    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    country: str = ormar.String(default=False, max_length=50, choices=["UK", "US", "Vietnam", "Colombia"])

# ormar >= 0.20
from enum import Enum

class Country(str, Enum):
    UK = "UK"
    US = "US"
    VIETNAM = "Vietnam"
    COLOMBIA = "Colombia"

class ArtistV20(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
        tablename="artists_v20"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    country: Country = ormar.Enum(enum_class=Country)

pydantic_only Field parameters are no longer supported

The pydantic_only field has been deprecated and removed in v 0.20. Ormar allows pydantic fields to be defined like normal pydantic models.

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import databases
import ormar
import sqlalchemy

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

# ormar < 0.20
class Dish(ormar.Model):
    class Meta:
        database = database
        metadata = metadata
        tablename = "dishes"


    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    cook: str = ormar.String(max_length=40, pydantic_only=True, default="sam")

# ormar >= 0.20
class DishV20(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
        tablename="dishes_v20"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    cook: str = "sam"  # this is normal pydantic field

The property_field decorator is no longer supported

The property_field decorator is used to provide a way to pass along the computed fields contained in the dictionary/serialized json representation of the model. Pydantic version 2.X introduces this possibility, so you should now switch to the native version of pydantic.

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import databases
import ormar
import sqlalchemy
import pydantic

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

# ormar < 0.20
class Employee(ormar.Model):
    class Meta:
        database = database
        metadata = metadata


    id: int = ormar.Integer(primary_key=True)
    first_name: str = ormar.String(max_length=100)
    last_name: str = ormar.String(max_length=100)

    @ormar.property_field()
    def full_name(self) -> str:
        return f"{self.first_name} {self.last_name}"

# ormar >= 0.20
class EmployeeV20(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
    )

    id: int = ormar.Integer(primary_key=True)
    first_name: str = ormar.String(max_length=100)
    last_name: str = ormar.String(max_length=100)

    @pydantic.computed_field()
    def full_name(self) -> str:
        return f"{self.first_name} {self.last_name}"

Defunct method

All methods listed below are deprecated and will be removed in ormar version 0.30.

dict() becomes model_dump()

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import databases
import ormar
import sqlalchemy

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

class Album(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
        tablename="albums"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    favorite: bool = ormar.Boolean(default=False)

album = Album(name="Dark Side of the Moon")

# ormar < 0.20
album_dict = album.dict()

# ormar >= 0.20
new_album_dict = album.model_dump()

Note that the parameters remain unchanged, i.e. include, exclude, etc.

json() becomes model_dump_json()

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import databases
import ormar
import sqlalchemy

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

class Album(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
        tablename="albums"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    favorite: bool = ormar.Boolean(default=False)

album = Album(name="Dark Side of the Moon")

# ormar < 0.20
album_json= album.json()

# ormar >= 0.20
new_album_dict = album.model_dump_json()

Note that the parameters remain unchanged, i.e. include, exclude, etc.

construct() becomes model_construct()

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import databases
import ormar
import sqlalchemy

database = databases.Database("sqlite:///db.sqlite")
metadata = sqlalchemy.MetaData()

class Album(ormar.Model):
    ormar_config = ormar.OrmarConfig(
        database=database,
        metadata=metadata,
        tablename="albums"
    )

    id: int = ormar.Integer(primary_key=True)
    name: str = ormar.String(max_length=100)
    favorite: bool = ormar.Boolean(default=False)

params = {
    "name": "Dark Side of the Moon",
    "favorite": True,
}
# ormar < 0.20
album = Album.construct(**params)

# ormar >= 0.20
album = Album.model_construct(**params)

To learn more about construction, see the pydantic documentation.