allOf

OpenAPI supports inheritance through the allOf directive.

See also

OpenAPI allOf documentation

OpenAPI documentation for the allOf directive.

Inheritance

OpenAlchemy documentation for the allOf directive.

OpenAlchemy interprets allOf to mean that the schemas in the directive are to be merged to form the final schema in place of the allOf directive. This allows for re-use of general schemas for particular schemas.

Column

When this is done for a property of an object, a generic definition for a property can be used as a base for properties. For example, the following OpenAPI specification defines generic IdBase and NameBase properties which are then used to define the Id and Name properties for the Employee and Division schemas:

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openapi: "3.0.0"

info:
  title: Test Schema
  description: API to illustrate allOf usage for columns.
  version: "0.1"

paths:
  /employee:
    get:
      summary: Used to retrieve all employees.
      responses:
        200:
          description: Return all employees from the database.
          content:
            application/json:
              schema:
                type: array
                items:
                  "$ref": "#/components/schemas/Employee"
  /division:
    get:
      summary: Used to retrieve all divisions.
      responses:
        200:
          description: Return all divisions from the database.
          content:
            application/json:
              schema:
                type: array
                items:
                  "$ref": "#/components/schemas/Division"

components:
  schemas:
    IdBase:
      type: integer
      description: Base for the id schema of an object.
      example: 0
      x-primary-key: true
    NameBase:
      type: string
      description: The name of the object.
      example: Object 1.
    Employee:
      description: Person that works for a company.
      type: object
      x-tablename: employee
      properties:
        id:
          allOf:
            - "$ref": "#/components/schemas/IdBase"
            - description: Unique identifier for the employee.
        name:
          allOf:
            - "$ref": "#/components/schemas/NameBase"
            - description: The name of the employee.
              example: David Andersson
        salary:
          type: number
          description: The amount of money the employee is paid.
          example: 1000000.00
    Division:
      description: A part of a company.
      type: object
      x-tablename: division
      properties:
        id:
          allOf:
            - "$ref": "#/components/schemas/IdBase"
            - description: Unique identifier for the division.
        name:
          allOf:
            - "$ref": "#/components/schemas/NameBase"
            - description: The name of the division.
              example: Engineering.

When the specification is fed to OpenAlchemy, the Id and Name columns for the employee and division tables are based on the IdBase and NameBase schemas, merged with any specific directives on the respective properties of the Employee and Division schemas. This is an implementation of the inheritance paradigm in software engineering:

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from open_alchemy import init_yaml

init_yaml("column-example-spec.yml", models_filename="column_models_auto.py")

OpenAlchemy will generate the following typed models:

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"""Autogenerated SQLAlchemy models based on OpenAlchemy models."""
# pylint: disable=no-member,super-init-not-called,unused-argument

import typing

import sqlalchemy
from sqlalchemy import orm

from open_alchemy import models

Base = models.Base  # type: ignore


class EmployeeDict(typing.TypedDict, total=False):
    """TypedDict for properties that are not required."""

    id: typing.Optional[int]
    name: typing.Optional[str]
    salary: typing.Optional[float]


class TEmployee(typing.Protocol):
    """
    SQLAlchemy model protocol.

    Person that works for a company.

    Attrs:
        id: Unique identifier for the employee.
        name: The name of the employee.
        salary: The amount of money the employee is paid.

    """

    # SQLAlchemy properties
    __table__: sqlalchemy.Table
    __tablename__: str
    query: orm.Query

    # Model properties
    id: "sqlalchemy.Column[typing.Optional[int]]"
    name: "sqlalchemy.Column[typing.Optional[str]]"
    salary: "sqlalchemy.Column[typing.Optional[float]]"

    def __init__(
        self,
        id: typing.Optional[int] = None,
        name: typing.Optional[str] = None,
        salary: typing.Optional[float] = None,
    ) -> None:
        """
        Construct.

        Args:
            id: Unique identifier for the employee.
            name: The name of the employee.
            salary: The amount of money the employee is paid.

        """
        ...

    @classmethod
    def from_dict(
        cls,
        id: typing.Optional[int] = None,
        name: typing.Optional[str] = None,
        salary: typing.Optional[float] = None,
    ) -> "TEmployee":
        """
        Construct from a dictionary (eg. a POST payload).

        Args:
            id: Unique identifier for the employee.
            name: The name of the employee.
            salary: The amount of money the employee is paid.

        Returns:
            Model instance based on the dictionary.

        """
        ...

    @classmethod
    def from_str(cls, value: str) -> "TEmployee":
        """
        Construct from a JSON string (eg. a POST payload).

        Returns:
            Model instance based on the JSON string.

        """
        ...

    def to_dict(self) -> EmployeeDict:
        """
        Convert to a dictionary (eg. to send back for a GET request).

        Returns:
            Dictionary based on the model instance.

        """
        ...

    def to_str(self) -> str:
        """
        Convert to a JSON string (eg. to send back for a GET request).

        Returns:
            JSON string based on the model instance.

        """
        ...


Employee: typing.Type[TEmployee] = models.Employee  # type: ignore


class DivisionDict(typing.TypedDict, total=False):
    """TypedDict for properties that are not required."""

    id: typing.Optional[int]
    name: typing.Optional[str]


class TDivision(typing.Protocol):
    """
    SQLAlchemy model protocol.

    A part of a company.

    Attrs:
        id: Unique identifier for the division.
        name: The name of the division.

    """

    # SQLAlchemy properties
    __table__: sqlalchemy.Table
    __tablename__: str
    query: orm.Query

    # Model properties
    id: "sqlalchemy.Column[typing.Optional[int]]"
    name: "sqlalchemy.Column[typing.Optional[str]]"

    def __init__(
        self, id: typing.Optional[int] = None, name: typing.Optional[str] = None
    ) -> None:
        """
        Construct.

        Args:
            id: Unique identifier for the division.
            name: The name of the division.

        """
        ...

    @classmethod
    def from_dict(
        cls, id: typing.Optional[int] = None, name: typing.Optional[str] = None
    ) -> "TDivision":
        """
        Construct from a dictionary (eg. a POST payload).

        Args:
            id: Unique identifier for the division.
            name: The name of the division.

        Returns:
            Model instance based on the dictionary.

        """
        ...

    @classmethod
    def from_str(cls, value: str) -> "TDivision":
        """
        Construct from a JSON string (eg. a POST payload).

        Returns:
            Model instance based on the JSON string.

        """
        ...

    def to_dict(self) -> DivisionDict:
        """
        Convert to a dictionary (eg. to send back for a GET request).

        Returns:
            Dictionary based on the model instance.

        """
        ...

    def to_str(self) -> str:
        """
        Convert to a JSON string (eg. to send back for a GET request).

        Returns:
            JSON string based on the model instance.

        """
        ...


Division: typing.Type[TDivision] = models.Division  # type: ignore

Model

allOf also works for objects. For example, the following OpenAPI specification defines a base schema with an id and name property. This is then used to define the Employee and Division schemas:

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openapi: "3.0.0"

info:
  title: Test Schema
  description: API to illustrate OpenAlchemy MVP.
  version: "0.1"

paths:
  /employee:
    get:
      summary: Used to retrieve all employees.
      responses:
        200:
          description: Return all employees from the database.
          content:
            application/json:
              schema:
                type: array
                items:
                  "$ref": "#/components/schemas/Employee"
  /division:
    get:
      summary: Used to retrieve all divisions.
      responses:
        200:
          description: Return all divisions from the database.
          content:
            application/json:
              schema:
                type: array
                items:
                  "$ref": "#/components/schemas/Division"

components:
  schemas:
    IdNameBase:
      description: Base schema with an id and name column.
      type: object
      properties:
        id:
          type: integer
          description: Unique identifier for the object.
          example: 0
          x-primary-key: true
        name:
          type: string
          description: The name of the object.
          example: Object 1.
    Division:
      allOf:
        - "$ref": "#/components/schemas/IdNameBase"
        - description: A part of a company.
          x-tablename: division
    Employee:
      allOf:
        - "$ref": "#/components/schemas/IdNameBase"
        - description: Person that works for a company.
          x-tablename: employee
          type: object
          properties:
            salary:
              type: number
              description: The amount of money the employee is paid.
              example: 1000000.00

The following file uses OpenAlchemy to generate the SQLAlchemy models:

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from open_alchemy import init_yaml

init_yaml("model-example-spec.yml", models_filename="model_models_auto.py")

OpenAlchemy will generate the following typed models:

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"""Autogenerated SQLAlchemy models based on OpenAlchemy models."""
# pylint: disable=no-member,super-init-not-called,unused-argument

import typing

import sqlalchemy
from sqlalchemy import orm

from open_alchemy import models

Base = models.Base  # type: ignore


class DivisionDict(typing.TypedDict, total=False):
    """TypedDict for properties that are not required."""

    id: typing.Optional[int]
    name: typing.Optional[str]


class TDivision(typing.Protocol):
    """
    SQLAlchemy model protocol.

    A part of a company.

    Attrs:
        id: Unique identifier for the object.
        name: The name of the object.

    """

    # SQLAlchemy properties
    __table__: sqlalchemy.Table
    __tablename__: str
    query: orm.Query

    # Model properties
    id: "sqlalchemy.Column[typing.Optional[int]]"
    name: "sqlalchemy.Column[typing.Optional[str]]"

    def __init__(
        self, id: typing.Optional[int] = None, name: typing.Optional[str] = None
    ) -> None:
        """
        Construct.

        Args:
            id: Unique identifier for the object.
            name: The name of the object.

        """
        ...

    @classmethod
    def from_dict(
        cls, id: typing.Optional[int] = None, name: typing.Optional[str] = None
    ) -> "TDivision":
        """
        Construct from a dictionary (eg. a POST payload).

        Args:
            id: Unique identifier for the object.
            name: The name of the object.

        Returns:
            Model instance based on the dictionary.

        """
        ...

    @classmethod
    def from_str(cls, value: str) -> "TDivision":
        """
        Construct from a JSON string (eg. a POST payload).

        Returns:
            Model instance based on the JSON string.

        """
        ...

    def to_dict(self) -> DivisionDict:
        """
        Convert to a dictionary (eg. to send back for a GET request).

        Returns:
            Dictionary based on the model instance.

        """
        ...

    def to_str(self) -> str:
        """
        Convert to a JSON string (eg. to send back for a GET request).

        Returns:
            JSON string based on the model instance.

        """
        ...


Division: typing.Type[TDivision] = models.Division  # type: ignore


class EmployeeDict(typing.TypedDict, total=False):
    """TypedDict for properties that are not required."""

    salary: typing.Optional[float]
    id: typing.Optional[int]
    name: typing.Optional[str]


class TEmployee(typing.Protocol):
    """
    SQLAlchemy model protocol.

    Person that works for a company.

    Attrs:
        salary: The amount of money the employee is paid.
        id: Unique identifier for the object.
        name: The name of the object.

    """

    # SQLAlchemy properties
    __table__: sqlalchemy.Table
    __tablename__: str
    query: orm.Query

    # Model properties
    salary: "sqlalchemy.Column[typing.Optional[float]]"
    id: "sqlalchemy.Column[typing.Optional[int]]"
    name: "sqlalchemy.Column[typing.Optional[str]]"

    def __init__(
        self,
        salary: typing.Optional[float] = None,
        id: typing.Optional[int] = None,
        name: typing.Optional[str] = None,
    ) -> None:
        """
        Construct.

        Args:
            salary: The amount of money the employee is paid.
            id: Unique identifier for the object.
            name: The name of the object.

        """
        ...

    @classmethod
    def from_dict(
        cls,
        salary: typing.Optional[float] = None,
        id: typing.Optional[int] = None,
        name: typing.Optional[str] = None,
    ) -> "TEmployee":
        """
        Construct from a dictionary (eg. a POST payload).

        Args:
            salary: The amount of money the employee is paid.
            id: Unique identifier for the object.
            name: The name of the object.

        Returns:
            Model instance based on the dictionary.

        """
        ...

    @classmethod
    def from_str(cls, value: str) -> "TEmployee":
        """
        Construct from a JSON string (eg. a POST payload).

        Returns:
            Model instance based on the JSON string.

        """
        ...

    def to_dict(self) -> EmployeeDict:
        """
        Convert to a dictionary (eg. to send back for a GET request).

        Returns:
            Dictionary based on the model instance.

        """
        ...

    def to_str(self) -> str:
        """
        Convert to a JSON string (eg. to send back for a GET request).

        Returns:
            JSON string based on the model instance.

        """
        ...


Employee: typing.Type[TEmployee] = models.Employee  # type: ignore

See also

Getting Started