Tiferet Flask - A Flask Extension for the Tiferet Framework

Introduction

Tiferet Flask extends the Tiferet Python framework to build Flask-based APIs using Domain-Driven Design (DDD). It uses tiferet-openapi as its domain backbone, providing a thin Flask integration layer on top of the shared OpenAPI abstraction.

Key components:

• build_flask_app / FlaskApp — assembles a Flask app from ApiRouter/ApiRoute domain objects using blueprint functions.
• FlaskApiContext — extends OpenApiContext with Swagger UI support.
• FlaskRequestContext — alias for OpenApiRequestContext with Pydantic serialization.

Getting Started

Prerequisites

• Python 3.10+
• A virtual environment (recommended)

Installation

pip install tiferet-flask

This installs tiferet-openapi (which transitively provides tiferet) along with Flask and Flask-CORS.

Project Structure

project_root/
├── calc_flask_api.py
└── app/
    ├── events/
    │   ├── __init__.py
    │   └── calc.py
    └── configs/
        ├── app.yml
        ├── openapi.yml
        ├── container.yml
        ├── error.yml
        └── feature.yml

Configuration

App Interface (app/configs/app.yml)

Define the Flask API interface using tiferet-openapi types:

interfaces:
  calc_flask_api:
    name: Calculator Flask API
    description: Arithmetic operations via Flask API
    module_path: tiferet_flask.contexts.flask
    class_name: FlaskApiContext
    attrs:
      get_routers_evt:
        module_path: tiferet_openapi.events.openapi
        class_name: GetRouters
      get_route_evt:
        module_path: tiferet_openapi.events.openapi
        class_name: GetRoute
      get_status_code_evt:
        module_path: tiferet_openapi.events.openapi
        class_name: GetStatusCode
      openapi_service:
        module_path: tiferet_openapi.repos.openapi
        class_name: OpenApiYamlRepository
        params:
          openapi_yaml_file: app/configs/openapi.yml

OpenAPI Configuration (app/configs/openapi.yml)

Define routers, routes, and error status codes using the openapi: root key:

openapi:
  routers:
    calc:
      prefix: /calc
      routes:
        add:
          path: /add
          methods: [POST, GET]
          status_code: 200
        subtract:
          path: /subtract
          methods: [POST, GET]
          status_code: 200
        divide:
          path: /divide
          methods: [POST, GET]
          status_code: 200
        sqrt:
          path: /sqrt
          methods: [POST, GET]
          status_code: 200
  errors:
    DIVISION_BY_ZERO: 400
    INVALID_INPUT: 422

Usage

Entry Point (calc_flask_api.py)

from tiferet_flask import FlaskApp

# Define the view function.
def view_func(**kwargs):
    from flask import request, jsonify

    data = dict(request.json) if request.is_json else {}
    data.update(dict(request.args))
    data.update(kwargs)
    headers = dict(request.headers)

    response, status_code = context.run(
        feature_id=request.endpoint,
        headers=headers,
        data=data,
    )
    return jsonify(response), status_code

# Build the Flask app with Swagger UI enabled.
flask_app = FlaskApp('calc_flask_api', view_func, swagger=True)

if __name__ == '__main__':
    flask_app.run(host='127.0.0.1', port=5000, debug=True)

Endpoints

# Add two numbers
curl -X POST http://127.0.0.1:5000/calc/add \
  -H "Content-Type: application/json" -d '{"a": 1, "b": 2}'
# Output: 3

# Square root
curl -X POST http://127.0.0.1:5000/calc/sqrt \
  -H "Content-Type: application/json" -d '{"a": 16}'
# Output: 4.0

# Division by zero
curl -X POST http://127.0.0.1:5000/calc/divide \
  -H "Content-Type: application/json" -d '{"a": 5, "b": 0}'
# Output: {"error_code": "DIVISION_BY_ZERO", ...}

Swagger UI

When swagger=True is passed to FlaskApp(), Swagger UI is available at:

• Swagger UI: http://127.0.0.1:5000/docs
• OpenAPI spec: http://127.0.0.1:5000/docs/openapi.json

Architecture

Tiferet Flask v1.0.0 delegates all domain, interface, event, mapper, and repository concerns to tiferet-openapi. Only two packages remain under tiferet_flask/:

• blueprints/ — Stateless blueprint functions (build_flask_app, build_blueprint, get_routers, run) that consume ApiRouter/ApiRoute from tiferet-openapi, map them to Flask Blueprints, and optionally register a Swagger UI blueprint. Exported as FlaskApp alias.
• contexts/ — FlaskApiContext is a thin subclass of OpenApiContext that adds create_swagger_blueprint(). FlaskRequestContext is an alias for OpenApiRequestContext.

For domain-level documentation (domain objects, events, mappers, repositories), see tiferet-openapi.

Migration from v0.4.x

• Builders → Blueprints: The FlaskAppBuilder class has been replaced by stateless blueprint functions. FlaskAppBuilder() → build_flask_app() / FlaskApp(). No more class instantiation — call the function directly.
• Imports: from tiferet_flask import FlaskAppBuilder → from tiferet_flask import FlaskApp (or build_flask_app).
• Usage: builder = FlaskAppBuilder(); builder.run(...) → flask_app = FlaskApp(interface_id, view_func, swagger=True).
• Dependencies: The direct tiferet>=2.0.0b1 dependency has been removed. Tiferet is now provided transitively through tiferet-openapi>=0.1.3.

Example

See the example/ directory for a complete calculator Flask API demonstrating the v1.0.0 architecture with Swagger support.

License

MIT