flask-backend

Flask Backend

Purpose

Define Flask backend application architecture: lightweight server setup, blueprint organization, extension integration, and WSGI deployment.

Agent Protocol

Trigger

User request includes: flask, flask backend, flask blueprint, flask app factory, flask sqlalchemy, flask extension, flask rest api, python flask.

Input Context

• Python version (3.10+)
• Flask version (3.x)
• Database ORM (SQLAlchemy, Peewee)
• API style (REST, Flask-RESTx)
• Template engine (Jinja2, none for SPA)
• Deployment (Gunicorn, uWSGI, serverless)

Output Artifact

A markdown document containing:

• Project structure
• Application factory pattern
• Blueprint organization
• Extension initialization pattern
• Error handling (app.errorhandler)
• Configuration management
• Testing (pytest, app.test_client)
• CLI commands (click integration)

Response Format

Produce the artifact directly. No preamble, no postamble, no explanations. No filler, no hedging. Compress output.

Completion Criteria

• Application factory creates configurable app instances
• Blueprints group related routes and templates
• Extensions initialized via init_app pattern
• Error handlers registered at app level
• Tests use app.test_client fixture

Max Response Length

4096 tokens

Workflow

Step 1: Project Setup

pip install flask flask-sqlalchemy flask-migrate pydantic
pip install pytest pytest-cov  # dev
pip install gunicorn  # production
pip install flask-cors flask-limiter redis  # optional

Step 2: Project Structure

project/
+-- app/
|   +-- __init__.py
|   +-- extensions.py
|   +-- config.py
|   +-- models/
|   |   +-- __init__.py
|   |   +-- order.py
|   |   +-- user.py
|   +-- blueprints/
|   |   +-- orders/
|   |   |   +-- __init__.py
|   |   |   +-- routes.py
|   |   |   +-- schemas.py
|   |   |   +-- service.py
|   |   +-- products/
|   |   |   +-- __init__.py
|   |   |   +-- routes.py
|   |   |   +-- service.py
|   |   +-- auth/
|   |   |   +-- __init__.py
|   |   |   +-- routes.py
|   |   |   +-- service.py
|   |   +-- health/
|   |       +-- __init__.py
|   |       +-- routes.py
|   +-- services/
|   |   +-- __init__.py
|   |   +-- order_service.py
|   |   +-- payment_service.py
|   +-- utils/
|   |   +-- __init__.py
|   |   +-- errors.py
|   |   +-- pagination.py
|   |   +-- decorators.py
|   +-- templates/
|       +-- base.html
|       +-- orders/
|           +-- list.html
|           +-- detail.html
+-- migrations/
+-- tests/
|   +-- conftest.py
|   +-- test_orders.py
|   +-- test_health.py
|   +-- factories.py
+-- .env
+-- .flaskenv
+-- requirements.txt
+-- wsgi.py
+-- Dockerfile