flask-pydantic-spec

What it is and what it does

Flask Pydantic Spec is a library that integrates Pydantic validation and OpenAPI documentation generation into Flask applications. It lets you define request and response schemas using Pydantic models, then automatically validates incoming requests against those schemas and generates interactive API documentation (Redoc or Swagger UI). Instead of writing separate YAML specs or manual validation logic, you annotate your Flask route handlers with Pydantic models, and the library handles validation, error responses (422 on failure), and documentation generation.

The library depends on pydantic for schema definition and validation, and inflection for string transformations. It supports validation of query parameters, JSON bodies, headers, and cookies, plus response type declarations. When validation fails, it returns a 422 status with structured error details. You access validated data via a context object attached to the request, though you can also use Flask's standard request object. The library began as a fork of Spectree and aims to reduce boilerplate by combining documentation and validation in one annotation-driven interface.

Use it for

• Build a REST API with automatic OpenAPI documentation and request validation without writing separate spec files.
• Validate incoming JSON payloads and query parameters against Pydantic models, returning 422 errors with detailed validation messages.
• Generate interactive Swagger UI or Redoc documentation automatically from your Flask route annotations.
• Enforce consistent request/response schemas across a Flask application using Pydantic's validation and serialization.
• Add before/after hooks to validation to log failures, record metrics, or customize error responses per endpoint.

Worth the install?

AI-flagged interpretation of the facts on this page. Verify before relying on it.

Install

flask-pydantic-spec on PyPI

Before you install

Low friction: pure Python wheel with only two runtime dependencies (pydantic and inflection). Last commit was recent; however, the project shows aging maintenance signals with only 1 star and 262 days since the last release.

Requires Python 3.9 or later.

License in practice

License status is unclear—no SPDX identifier or raw license text is available in the package metadata. Verify the actual license before using in proprietary or restricted contexts.

Quickstart

pip install flask-pydantic-spec

from flask import Flask
from pydantic import BaseModel
from flask_pydantic_spec import FlaskPydanticSpec, Response, Request

class UserModel(BaseModel):
    name: str
    age: int

app = Flask(__name__)
api = FlaskPydanticSpec('flask')

@app.route('/api/user', methods=['POST'])
@api.validate(body=Request(UserModel), resp=Response(HTTP_200=UserModel))
def create_user():
    return {'name': 'alice', 'age': 18}

api.register(app)
app.run()

Package facts

Evidence: flask_pydantic_spec-0.8.7-py3-none-any.whl

Tags

More Python Modules packages

See also flask-openapi3 · Flask-Pydantic · spectree · openapi-pydantic · openapi-schema-pydantic · quart-schema · pydantic-handlebars · APIFlask · sanic-ext · flask-swagger