Add complete simple messaging app with FastAPI

- Implement user authentication with JWT tokens
- Add messaging system for sending/receiving messages
- Create SQLite database with SQLAlchemy models
- Set up Alembic for database migrations
- Add health check endpoint
- Include comprehensive API documentation
- Support user registration, login, and message management
- Enable conversation history and user listing

README.md

@@ -1,3 +1,72 @@
-# FastAPI Application
+# Simple Messaging App
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple messaging application built with FastAPI, SQLAlchemy, and SQLite.
+
+## Features
+
+- User registration and authentication with JWT tokens
+- Send and receive messages between users
+- View conversation history
+- Health check endpoint
+- API documentation with Swagger UI
+
+## Tech Stack
+
+- **FastAPI**: Modern, fast web framework for building APIs
+- **SQLAlchemy**: SQL toolkit and ORM
+- **SQLite**: Lightweight database
+- **Alembic**: Database migration tool
+- **JWT**: JSON Web Tokens for authentication
+- **Bcrypt**: Password hashing
+- **Ruff**: Fast Python linter
+
+## Installation
+
+1. Install dependencies:
+```bash
+pip install -r requirements.txt
+```
+
+2. Run database migrations:
+```bash
+alembic upgrade head
+```
+
+3. Start the application:
+```bash
+uvicorn main:app --reload
+```
+
+The application will be available at `http://localhost:8000`
+
+## API Documentation
+
+- Swagger UI: `http://localhost:8000/docs`
+- ReDoc: `http://localhost:8000/redoc`
+- OpenAPI JSON: `http://localhost:8000/openapi.json`
+
+## Endpoints
+
+### Authentication
+- `POST /auth/register` - Register a new user
+- `POST /auth/login` - Login user and get access token
+
+### Messages
+- `POST /messages/send` - Send a message to another user
+- `GET /messages/received` - Get received messages
+- `GET /messages/sent` - Get sent messages
+- `GET /messages/conversation/{user_id}` - Get conversation with specific user
+- `GET /messages/users` - Get list of all users
+
+### Health
+- `GET /health` - Health check endpoint
+
+## Environment Variables
+
+Set the following environment variables:
+
+- `SECRET_KEY`: JWT secret key for token signing (default: "your-secret-key-here")
+
+## Database
+
+The application uses SQLite database stored at `/app/storage/db/db.sqlite`. The database schema is managed with Alembic migrations.

alembic.ini

@@ -0,0 +1,42 @@
+[alembic]
+script_location = alembic
+prepend_sys_path = .
+version_path_separator = os
+sqlalchemy.url = sqlite:////app/storage/db/db.sqlite
+output_encoding = utf-8
+
+[post_write_hooks]
+
+[loggers]
+keys = root,sqlalchemy,alembic
+
+[handlers]
+keys = console
+
+[formatters]
+keys = generic
+
+[logger_root]
+level = WARN
+handlers = console
+qualname =
+
+[logger_sqlalchemy]
+level = WARN
+handlers =
+qualname = sqlalchemy.engine
+
+[logger_alembic]
+level = INFO
+handlers =
+qualname = alembic
+
+[handler_console]
+class = StreamHandler
+args = (sys.stderr,)
+level = NOTSET
+formatter = generic
+
+[formatter_generic]
+format = %(levelname)-5.5s [%(name)s] %(message)s
+datefmt = %H:%M:%S

alembic/env.py

@@ -0,0 +1,54 @@
+from logging.config import fileConfig
+import sys
+import os
+from pathlib import Path
+
+sys.path.append(str(Path(__file__).resolve().parent.parent))
+
+from sqlalchemy import engine_from_config
+from sqlalchemy import pool
+
+from alembic import context
+
+from app.db.base import Base
+from app.models.user import User
+from app.models.message import Message
+
+config = context.config
+
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+target_metadata = Base.metadata
+
+def run_migrations_offline() -> None:
+    url = config.get_main_option("sqlalchemy.url")
+    context.configure(
+        url=url,
+        target_metadata=target_metadata,
+        literal_binds=True,
+        dialect_opts={"paramstyle": "named"},
+    )
+
+    with context.begin_transaction():
+        context.run_migrations()
+
+def run_migrations_online() -> None:
+    connectable = engine_from_config(
+        config.get_section(config.config_ini_section),
+        prefix="sqlalchemy.",
+        poolclass=pool.NullPool,
+    )
+
+    with connectable.connect() as connection:
+        context.configure(
+            connection=connection, target_metadata=target_metadata
+        )
+
+        with context.begin_transaction():
+            context.run_migrations()
+
+if context.is_offline_mode():
+    run_migrations_offline()
+else:
+    run_migrations_online()

alembic/script.py.mako

@@ -0,0 +1,24 @@
+"""${message}
+
+Revision ID: ${up_revision}
+Revises: ${down_revision | comma,n}
+Create Date: ${create_date}
+
+"""
+from alembic import op
+import sqlalchemy as sa
+${imports if imports else ""}
+
+# revision identifiers, used by Alembic.
+revision = ${repr(up_revision)}
+down_revision = ${repr(down_revision)}
+branch_labels = ${repr(branch_labels)}
+depends_on = ${repr(depends_on)}
+
+
+def upgrade() -> None:
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade() -> None:
+    ${downgrades if downgrades else "pass"}

alembic/versions/001_initial_migration.py

@@ -0,0 +1,54 @@
+"""Initial migration
+
+Revision ID: 001
+Revises: 
+Create Date: 2024-01-01 00:00:00.000000
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+# revision identifiers, used by Alembic.
+revision = '001'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # Create users table
+    op.create_table('users',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('email', sa.String(), nullable=False),
+    sa.Column('username', sa.String(), nullable=False),
+    sa.Column('hashed_password', sa.String(), nullable=False),
+    sa.Column('is_active', sa.Boolean(), nullable=True),
+    sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=True),
+    sa.Column('updated_at', sa.DateTime(timezone=True), nullable=True),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_users_email'), 'users', ['email'], unique=True)
+    op.create_index(op.f('ix_users_id'), 'users', ['id'], unique=False)
+    op.create_index(op.f('ix_users_username'), 'users', ['username'], unique=True)
+    
+    # Create messages table
+    op.create_table('messages',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('sender_id', sa.Integer(), nullable=False),
+    sa.Column('receiver_id', sa.Integer(), nullable=False),
+    sa.Column('content', sa.Text(), nullable=False),
+    sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=True),
+    sa.ForeignKeyConstraint(['receiver_id'], ['users.id'], ),
+    sa.ForeignKeyConstraint(['sender_id'], ['users.id'], ),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_messages_id'), 'messages', ['id'], unique=False)
+
+
+def downgrade() -> None:
+    op.drop_index(op.f('ix_messages_id'), table_name='messages')
+    op.drop_table('messages')
+    op.drop_index(op.f('ix_users_username'), table_name='users')
+    op.drop_index(op.f('ix_users_id'), table_name='users')
+    op.drop_index(op.f('ix_users_email'), table_name='users')
+    op.drop_table('users')

app/auth/auth.py

@@ -0,0 +1,71 @@
+import os
+from datetime import datetime, timedelta
+from typing import Optional
+from jose import JWTError, jwt
+from passlib.context import CryptContext
+from fastapi import Depends, HTTPException, status
+from fastapi.security import HTTPBearer, HTTPAuthorizationCredentials
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+from app.models.user import User
+from app.schemas.user import TokenData
+
+SECRET_KEY = os.getenv("SECRET_KEY", "your-secret-key-here")
+ALGORITHM = "HS256"
+ACCESS_TOKEN_EXPIRE_MINUTES = 30
+
+pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
+security = HTTPBearer()
+
+def verify_password(plain_password, hashed_password):
+    return pwd_context.verify(plain_password, hashed_password)
+
+def get_password_hash(password):
+    return pwd_context.hash(password)
+
+def get_user_by_email(db: Session, email: str):
+    return db.query(User).filter(User.email == email).first()
+
+def authenticate_user(db: Session, email: str, password: str):
+    user = get_user_by_email(db, email)
+    if not user:
+        return False
+    if not verify_password(password, user.hashed_password):
+        return False
+    return user
+
+def create_access_token(data: dict, expires_delta: Optional[timedelta] = None):
+    to_encode = data.copy()
+    if expires_delta:
+        expire = datetime.utcnow() + expires_delta
+    else:
+        expire = datetime.utcnow() + timedelta(minutes=15)
+    to_encode.update({"exp": expire})
+    encoded_jwt = jwt.encode(to_encode, SECRET_KEY, algorithm=ALGORITHM)
+    return encoded_jwt
+
+async def get_current_user(credentials: HTTPAuthorizationCredentials = Depends(security), db: Session = Depends(get_db)):
+    credentials_exception = HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Could not validate credentials",
+        headers={"WWW-Authenticate": "Bearer"},
+    )
+    try:
+        token = credentials.credentials
+        payload = jwt.decode(token, SECRET_KEY, algorithms=[ALGORITHM])
+        email: str = payload.get("sub")
+        if email is None:
+            raise credentials_exception
+        token_data = TokenData(email=email)
+    except JWTError:
+        raise credentials_exception
+    user = get_user_by_email(db, email=token_data.email)
+    if user is None:
+        raise credentials_exception
+    return user
+
+async def get_current_active_user(current_user: User = Depends(get_current_user)):
+    if not current_user.is_active:
+        raise HTTPException(status_code=400, detail="Inactive user")
+    return current_user

app/db/base.py

@@ -0,0 +1,3 @@
+from sqlalchemy.ext.declarative import declarative_base
+
+Base = declarative_base()

app/db/session.py

@@ -0,0 +1,26 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from app.db.base import Base
+
+DB_DIR = Path("/app/storage/db")
+DB_DIR.mkdir(parents=True, exist_ok=True)
+
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{DB_DIR}/db.sqlite"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+Base.metadata.create_all(bind=engine)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/models/message.py

@@ -0,0 +1,16 @@
+from sqlalchemy import Column, Integer, String, DateTime, ForeignKey, Text
+from sqlalchemy.sql import func
+from sqlalchemy.orm import relationship
+from app.db.base import Base
+
+class Message(Base):
+    __tablename__ = "messages"
+
+    id = Column(Integer, primary_key=True, index=True)
+    sender_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    receiver_id = Column(Integer, ForeignKey("users.id"), nullable=False)
+    content = Column(Text, nullable=False)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+
+    sender = relationship("User", foreign_keys=[sender_id])
+    receiver = relationship("User", foreign_keys=[receiver_id])

app/models/user.py

@@ -0,0 +1,14 @@
+from sqlalchemy import Column, Integer, String, DateTime, Boolean
+from sqlalchemy.sql import func
+from app.db.base import Base
+
+class User(Base):
+    __tablename__ = "users"
+
+    id = Column(Integer, primary_key=True, index=True)
+    email = Column(String, unique=True, index=True, nullable=False)
+    username = Column(String, unique=True, index=True, nullable=False)
+    hashed_password = Column(String, nullable=False)
+    is_active = Column(Boolean, default=True)
+    created_at = Column(DateTime(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), onupdate=func.now())

app/routers/auth.py

@@ -0,0 +1,58 @@
+from datetime import timedelta
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+from app.models.user import User
+from app.schemas.user import UserCreate, UserLogin, Token, User as UserSchema
+from app.auth.auth import (
+    authenticate_user,
+    create_access_token,
+    get_password_hash,
+    get_user_by_email,
+    ACCESS_TOKEN_EXPIRE_MINUTES
+)
+
+router = APIRouter()
+
+@router.post("/register", response_model=UserSchema)
+def register_user(user: UserCreate, db: Session = Depends(get_db)):
+    db_user = get_user_by_email(db, email=user.email)
+    if db_user:
+        raise HTTPException(
+            status_code=400,
+            detail="Email already registered"
+        )
+    
+    db_user = db.query(User).filter(User.username == user.username).first()
+    if db_user:
+        raise HTTPException(
+            status_code=400,
+            detail="Username already taken"
+        )
+    
+    hashed_password = get_password_hash(user.password)
+    db_user = User(
+        email=user.email,
+        username=user.username,
+        hashed_password=hashed_password
+    )
+    db.add(db_user)
+    db.commit()
+    db.refresh(db_user)
+    return db_user
+
+@router.post("/login", response_model=Token)
+def login_user(user_credentials: UserLogin, db: Session = Depends(get_db)):
+    user = authenticate_user(db, user_credentials.email, user_credentials.password)
+    if not user:
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect email or password",
+            headers={"WWW-Authenticate": "Bearer"},
+        )
+    access_token_expires = timedelta(minutes=ACCESS_TOKEN_EXPIRE_MINUTES)
+    access_token = create_access_token(
+        data={"sub": user.email}, expires_delta=access_token_expires
+    )
+    return {"access_token": access_token, "token_type": "bearer"}

app/routers/health.py

@@ -0,0 +1,21 @@
+from fastapi import APIRouter, Depends
+from sqlalchemy.orm import Session
+from sqlalchemy import text
+
+from app.db.session import get_db
+
+router = APIRouter()
+
+@router.get("/health")
+def health_check(db: Session = Depends(get_db)):
+    try:
+        db.execute(text("SELECT 1"))
+        database_status = "healthy"
+    except Exception as e:
+        database_status = f"unhealthy: {str(e)}"
+    
+    return {
+        "status": "healthy" if database_status == "healthy" else "unhealthy",
+        "database": database_status,
+        "service": "Simple Messaging App"
+    }

app/routers/messages.py

@@ -0,0 +1,91 @@
+from typing import List
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+from app.models.message import Message
+from app.models.user import User
+from app.schemas.message import MessageCreate, Message as MessageSchema
+from app.auth.auth import get_current_active_user
+
+router = APIRouter()
+
+@router.post("/send", response_model=MessageSchema)
+def send_message(
+    message: MessageCreate,
+    current_user: User = Depends(get_current_active_user),
+    db: Session = Depends(get_db)
+):
+    receiver = db.query(User).filter(User.id == message.receiver_id).first()
+    if not receiver:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Receiver not found"
+        )
+    
+    if receiver.id == current_user.id:
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail="Cannot send message to yourself"
+        )
+    
+    db_message = Message(
+        sender_id=current_user.id,
+        receiver_id=message.receiver_id,
+        content=message.content
+    )
+    db.add(db_message)
+    db.commit()
+    db.refresh(db_message)
+    
+    return db_message
+
+@router.get("/received", response_model=List[MessageSchema])
+def get_received_messages(
+    current_user: User = Depends(get_current_active_user),
+    db: Session = Depends(get_db)
+):
+    messages = db.query(Message).filter(
+        Message.receiver_id == current_user.id
+    ).order_by(Message.created_at.desc()).all()
+    
+    return messages
+
+@router.get("/sent", response_model=List[MessageSchema])
+def get_sent_messages(
+    current_user: User = Depends(get_current_active_user),
+    db: Session = Depends(get_db)
+):
+    messages = db.query(Message).filter(
+        Message.sender_id == current_user.id
+    ).order_by(Message.created_at.desc()).all()
+    
+    return messages
+
+@router.get("/conversation/{user_id}", response_model=List[MessageSchema])
+def get_conversation(
+    user_id: int,
+    current_user: User = Depends(get_current_active_user),
+    db: Session = Depends(get_db)
+):
+    other_user = db.query(User).filter(User.id == user_id).first()
+    if not other_user:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="User not found"
+        )
+    
+    messages = db.query(Message).filter(
+        ((Message.sender_id == current_user.id) & (Message.receiver_id == user_id)) |
+        ((Message.sender_id == user_id) & (Message.receiver_id == current_user.id))
+    ).order_by(Message.created_at.asc()).all()
+    
+    return messages
+
+@router.get("/users", response_model=List[dict])
+def get_users(
+    current_user: User = Depends(get_current_active_user),
+    db: Session = Depends(get_db)
+):
+    users = db.query(User).filter(User.id != current_user.id).all()
+    return [{"id": user.id, "username": user.username, "email": user.email} for user in users]

app/schemas/message.py

@@ -0,0 +1,20 @@
+from pydantic import BaseModel
+from datetime import datetime
+from typing import Optional
+
+class MessageBase(BaseModel):
+    content: str
+
+class MessageCreate(MessageBase):
+    receiver_id: int
+
+class Message(MessageBase):
+    id: int
+    sender_id: int
+    receiver_id: int
+    created_at: datetime
+    sender: Optional[dict] = None
+    receiver: Optional[dict] = None
+
+    class Config:
+        from_attributes = True

app/schemas/user.py

@@ -0,0 +1,30 @@
+from pydantic import BaseModel, EmailStr
+from datetime import datetime
+from typing import Optional
+
+class UserBase(BaseModel):
+    email: EmailStr
+    username: str
+
+class UserCreate(UserBase):
+    password: str
+
+class UserLogin(BaseModel):
+    email: EmailStr
+    password: str
+
+class User(UserBase):
+    id: int
+    is_active: bool
+    created_at: datetime
+    updated_at: Optional[datetime] = None
+
+    class Config:
+        from_attributes = True
+
+class Token(BaseModel):
+    access_token: str
+    token_type: str
+
+class TokenData(BaseModel):
+    email: Optional[str] = None

main.py

@@ -0,0 +1,32 @@
+from fastapi import FastAPI
+from fastapi.middleware.cors import CORSMiddleware
+from pathlib import Path
+
+from app.routers import auth, messages, health
+
+app = FastAPI(
+    title="Simple Messaging App",
+    description="A simple messaging application built with FastAPI",
+    version="1.0.0",
+    openapi_url="/openapi.json"
+)
+
+app.add_middleware(
+    CORSMiddleware,
+    allow_origins=["*"],
+    allow_credentials=True,
+    allow_methods=["*"],
+    allow_headers=["*"],
+)
+
+app.include_router(auth.router, prefix="/auth", tags=["auth"])
+app.include_router(messages.router, prefix="/messages", tags=["messages"])
+app.include_router(health.router, tags=["health"])
+
+@app.get("/")
+async def root():
+    return {
+        "title": "Simple Messaging App",
+        "documentation": "/docs",
+        "health_check": "/health"
+    }

requirements.txt

@@ -0,0 +1,9 @@
+fastapi==0.104.1
+uvicorn==0.24.0
+sqlalchemy==2.0.23
+alembic==1.12.1
+python-multipart==0.0.6
+python-jose[cryptography]==3.3.0
+passlib[bcrypt]==1.7.4
+python-decouple==3.8
+ruff==0.1.6