CivicMesh Backend

FastAPI • PostgreSQL • SQLAlchemy

This repository contains the backend API for CivicMesh, a community-driven mobile application developed to help residents report local issues, volunteer to resolve them, and track progress. The backend provides user authentication, issue management, image uploads, and database operations.

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Overview

The backend is built using FastAPI, with SQLAlchemy for ORM and PostgreSQL as the database. It exposes RESTful API endpoints that support:

• User creation and authentication
• Issue (post) creation and retrieval
• Filtering and updating posts
• Image upload and retrieval
• Basic authentication for protected routes

This API is intended for use with a React Native mobile frontend.

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Features

User Management

• User registration
• Secure password hashing using bcrypt
• Credential verification during login

Issue and Post Management

• Create new posts (community issues)
• Retrieve posts by user, category, active status, or ID
• Update existing posts
• Support for geolocation fields (latitude and longitude)
• Automatic timestamp generation

Image Handling

• Upload images for posts
• Store image data as binary in the database
• Retrieve images by post ID

Authentication

• HTTP Basic authentication for protected routes
• JWT utilities included in auth.py for possible future integration

Database

• PostgreSQL database with three main tables:
  • users
  • posts
  • images

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Tech Stack

Component	Technology
Backend Framework	FastAPI
ORM	SQLAlchemy
Database	PostgreSQL
Authentication	HTTP Basic + bcrypt
Image Storage	PostgreSQL (LargeBinary)
Dependencies	Listed in requirements.txt
Deployment	Render (CI/CD)

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Project Structure

civicmesh-backend/
│── auth.py
│── database.py
│── main.py
│── models.py
│── requirements.txt
│── README.md

main.py

Contains the core FastAPI application and routes, including:

• User registration
• Login handling
• Post creation
• Filtering and retrieving posts
• Updating posts
• Image upload and retrieval

auth.py

Includes:

• JWT configuration
• User creation under /auth/
• Password hashing utilities
• OAuth2PasswordBearer declaration

database.py

Defines the database connection, SQLAlchemy engine, session handling, and declarative base.

models.py

Defines SQLAlchemy ORM models for:

• User
• Post
• Image

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Installation and Setup

1. Clone the Repository

git clone https://github.com/your-username/civicmesh-backend.git
cd civicmesh-backend

2. Create and Activate a Virtual Environment

python3 -m venv venv
source venv/bin/activate      # macOS/Linux
venv\Scripts�ctivate         # Windows

3. Install Dependencies

pip install -r requirements.txt

4. Configure the Database

Update the PostgreSQL connection URL in database.py:

URL_DATABASE = "postgresql://username:password@host:port/dbname"

5. Run the Server

uvicorn main:app --reload

The API will run at:

http://localhost:8000

API documentation pages (generated by FastAPI):

http://localhost:8000/docs
http://localhost:8000/redoc

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API Endpoints

User Endpoints

Method	Endpoint	Description
POST	/users/	Create a new user
GET	/login/	Authenticate user with username and password

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Post Endpoints

Method	Endpoint	Description
POST	/posts/	Create a new post
GET	/posts/all/	Retrieve all posts
GET	/posts/{post_id}	Retrieve a specific post
GET	/posts/by_user/{user_id}	Retrieve posts created by a specific user
GET	/posts/category/{category}	Retrieve posts matching a specific category
GET	/posts/active/	Retrieve all active posts
PUT	/posts/{post_id}	Update an existing post

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Image Endpoints

Method	Endpoint	Description
POST	/upload-image/{post_id}	Upload an image for a post
GET	/image/{post_id}	Fetch the image associated with a post

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Database Schema

Users Table

Field	Type
id	Integer (Primary Key)
first_name	String
last_name	String
username	String (Unique)
password	String (Hashed)

Posts Table

Field	Type
id	Integer (Primary Key)
title	String
body	Text
user_id	Integer (Foreign Key: users.id)
category	String
subcategory	String
created_at	DateTime
longitude	Float
latitude	Float
image_url	String
is_active	Boolean

Images Table

Field	Type
id	Integer (Primary Key)
post_id	Integer (Foreign Key: posts.id)
image_data	Binary
image_url	String

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Example Requests

Create User

curl -X POST http://localhost:8000/users/ -H "Content-Type: application/json" -d '{
  "first_name": "John",
  "last_last": "Doe",
  "username": "john123",
  "password": "password123"
}'

Login

curl -X GET "http://localhost:8000/login/?username=john123&password=password123"

Create Post

curl -X POST http://localhost:8000/posts/ -H "Content-Type: application/json" -d '{
  "title": "Broken streetlight",
  "body": "Streetlight near Block C is not working.",
  "user_id": 1,
  "category": "Infrastructure",
  "longitude": 42.123,
  "latitude": -93.456
}'

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Future Improvements

• Implement full JWT authentication
• Add role-based access control (admin, volunteer, resident)
• Migrate image storage to AWS S3 or Firebase Storage
• Add notification support for post updates
• Integrate WebSocket-based real-time updates

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Contributors

• Backend Development: Nagasharan Sathish, Abhaya Neupane, Yashas Suresh
• Mobile Application Development: Nagasharan Sathish, Abhaya Neupane, Yashas Suresh