openapi-client-gen 0.2.1

Generate Python async clients from OpenAPI specs with ExternalService pattern

openapi-client-gen

Generate Python async API clients from OpenAPI 3.x specifications with Pydantic v2 support.

Features

• Generates Pydantic v2 models from OpenAPI schemas
• Creates async service classes extending ExternalService
• Handles query parameters, path parameters, and request bodies
• Supports custom Jinja2 templates for service generation
• Automatic enum value normalization (lowercase)
• Handles Python reserved words in parameter names
• Deduplicates operation names automatically

Installation

pip install openapi-client-gen

For full schema generation (recommended):

pip install openapi-client-gen[schemas]

Quick Start

CLI Usage

openapi-client-gen -i openapi.json -o ./client

openapi-client-gen -i openapi.json -o ./client --no-lowercase-enums

openapi-client-gen -i openapi.json -o ./client --template my_service.jinja2

Programmatic Usage

from pathlib import Path
from openapi_client_gen import parse_openapi, generate_schemas, generate_service

spec = parse_openapi(Path("openapi.json"))

generate_schemas(
    spec_path=Path("openapi.json"),
    output_path=Path("client/schemas.py"),
    lowercase_enums=True,
)

generate_service(
    spec=spec,
    output_path=Path("client/service.py"),
)

Generated Code Structure

client/
  __init__.py
  schemas.py
  service.py

Requirements

• Python 3.10+
• external_service library (for generated clients)
• jinja2 (for template rendering)
• pydantic>=2.0 (for schema validation)

Optional

• datamodel-code-generator (for better schema generation)

API Reference

parse_openapi(spec_path: Path) -> ParsedSpec

Parse an OpenAPI JSON file and return a structured representation.

generate_schemas(spec_path: Path, output_path: Path, lowercase_enums: bool = True)

Generate Pydantic models from OpenAPI schemas.

generate_service(spec: ParsedSpec, output_path: Path, template_path: Path | None = None)

Generate an async service class from parsed specification.

Custom Templates

You can provide custom Jinja2 templates for service generation. The template receives:

• operations: List of Operation objects
• schema_imports: List of schema names to import
• title: API title
• version: API version

License

MIT