Implement simple Todo application with FastAPI and SQLite

- Set up project structure
- Configure SQLite database connection
- Create Todo model and schema
- Implement CRUD API endpoints for todo items
- Add health check endpoint
- Update README with documentation

generated with BackendIM... (backend.im)

README.md

@@ -1,3 +1,46 @@
-# FastAPI Application
+# Simple Todo Application
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A simple Todo application API built with FastAPI and SQLite.
+
+## Features
+
+- Create, read, update, and delete todo items
+- Filter todos by completion status
+- Pagination support
+- Health check endpoint
+
+## API Endpoints
+
+- `GET /api/todos`: List all todos with optional filtering and pagination
+- `POST /api/todos`: Create a new todo
+- `GET /api/todos/{todo_id}`: Get a specific todo by ID
+- `PATCH /api/todos/{todo_id}`: Update a todo
+- `DELETE /api/todos/{todo_id}`: Delete a todo
+- `GET /health`: Application health check
+
+## Getting Started
+
+1. Install dependencies:
+   ```
+   pip install -r requirements.txt
+   ```
+
+2. Run the application:
+   ```
+   uvicorn main:app --reload
+   ```
+
+3. Access the API documentation:
+   - Swagger UI: http://localhost:8000/docs
+   - ReDoc: http://localhost:8000/redoc
+
+## Data Model
+
+### Todo
+
+- `id`: Integer (primary key)
+- `title`: String (required)
+- `description`: String (optional)
+- `completed`: Boolean (default: false)
+- `created_at`: DateTime (auto-generated)
+- `updated_at`: DateTime (auto-updated)

alembic.ini

@@ -0,0 +1,84 @@
+# A generic, single database configuration.
+
+[alembic]
+# path to migration scripts
+script_location = alembic
+
+# template used to generate migration files
+# file_template = %%(rev)s_%%(slug)s
+
+# timezone to use when rendering the date
+# within the migration file as well as the filename.
+# string value is passed to dateutil.tz.gettz()
+# leave blank for localtime
+# timezone =
+
+# max length of characters to apply to the
+# "slug" field
+# truncate_slug_length = 40
+
+# set to 'true' to run the environment during
+# the 'revision' command, regardless of autogenerate
+# revision_environment = false
+
+# set to 'true' to allow .pyc and .pyo files without
+# a source .py file to be detected as revisions in the
+# versions/ directory
+# sourceless = false
+
+# version location specification; this defaults
+# to alembic/versions.  When using multiple version
+# directories, initial revisions must be specified with --version-path
+# version_locations = %(here)s/bar %(here)s/bat alembic/versions
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url = 
+
+[post_write_hooks]
+# post_write_hooks defines scripts or Python functions that are run
+# on newly generated revision scripts.  See the documentation for further
+# detail and examples
+
+# format using "black" - use the console_scripts runner, against the "black" entrypoint
+# hooks=black
+# black.type=console_scripts
+# black.entrypoint=black
+# black.options=-l 79
+
+# Logging configuration
+[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 +1,86 @@
+from logging.config import fileConfig
+from pathlib import Path
+
+from sqlalchemy import pool
+from sqlalchemy import engine_from_config
+
+from alembic import context
+
+# this is the Alembic Config object, which provides
+# access to the values within the .ini file in use.
+config = context.config
+
+# Interpret the config file for Python logging.
+# This line sets up loggers basically.
+if config.config_file_name is not None:
+    fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+from app.models import Todo
+from app.db.session import Base
+target_metadata = Base.metadata
+
+# other values from the config, defined by the needs of env.py,
+# can be acquired:
+# my_important_option = config.get_main_option("my_important_option")
+# ... etc.
+
+# Set the database URL 
+from app.core.config import settings
+DB_DIR = settings.DB_DIR
+DB_DIR.mkdir(parents=True, exist_ok=True)
+config.set_main_option("sqlalchemy.url", f"sqlite:///{DB_DIR}/db.sqlite")
+
+def run_migrations_offline() -> None:
+    """Run migrations in 'offline' mode.
+
+    This configures the context with just a URL
+    and not an Engine, though an Engine is acceptable
+    here as well.  By skipping the Engine creation
+    we don't even need a DBAPI to be available.
+
+    Calls to context.execute() here emit the given string to the
+    script output.
+
+    """
+    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:
+    """Run migrations in 'online' mode.
+
+    In this scenario we need to create an Engine
+    and associate a connection with the context.
+
+    """
+    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/1_initial_migration.py

@@ -0,0 +1,40 @@
+"""Initial migration
+
+Revision ID: 1_initial_migration
+Revises: 
+Create Date: 2025-05-13
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '1_initial_migration'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('todos',
+    sa.Column('id', sa.Integer(), nullable=False),
+    sa.Column('title', sa.String(), nullable=False),
+    sa.Column('description', sa.String(), nullable=True),
+    sa.Column('completed', sa.Boolean(), nullable=False, default=False),
+    sa.Column('created_at', sa.DateTime(), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+    sa.Column('updated_at', sa.DateTime(), server_default=sa.text('(CURRENT_TIMESTAMP)'), nullable=False),
+    sa.PrimaryKeyConstraint('id')
+    )
+    op.create_index(op.f('ix_todos_id'), 'todos', ['id'], unique=False)
+    op.create_index(op.f('ix_todos_title'), 'todos', ['title'], unique=False)
+    # ### end Alembic commands ###
+
+
+def downgrade() -> None:
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_index(op.f('ix_todos_title'), table_name='todos')
+    op.drop_index(op.f('ix_todos_id'), table_name='todos')
+    op.drop_table('todos')
+    # ### end Alembic commands ###

app/api/routers.py

@@ -0,0 +1,69 @@
+from typing import List, Optional
+from fastapi import APIRouter, Depends, HTTPException, Query, status
+from sqlalchemy.orm import Session
+
+from app.db.session import get_db
+from app.models.todo import Todo as TodoModel
+from app.schemas.todo import Todo, TodoCreate, TodoUpdate
+
+todos_router = APIRouter(prefix="/todos", tags=["todos"])
+
+@todos_router.post("/", response_model=Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(todo_in: TodoCreate, db: Session = Depends(get_db)):
+    """Create a new todo item"""
+    db_todo = TodoModel(**todo_in.dict())
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+@todos_router.get("/", response_model=List[Todo])
+def read_todos(
+    skip: int = 0, 
+    limit: int = 100, 
+    completed: Optional[bool] = None,
+    db: Session = Depends(get_db)
+):
+    """Get all todo items with optional filtering"""
+    query = db.query(TodoModel)
+    
+    if completed is not None:
+        query = query.filter(TodoModel.completed == completed)
+    
+    todos = query.offset(skip).limit(limit).all()
+    return todos
+
+@todos_router.get("/{todo_id}", response_model=Todo)
+def read_todo(todo_id: int, db: Session = Depends(get_db)):
+    """Get a specific todo item by ID"""
+    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    return db_todo
+
+@todos_router.patch("/{todo_id}", response_model=Todo)
+def update_todo(todo_id: int, todo_in: TodoUpdate, db: Session = Depends(get_db)):
+    """Update a todo item"""
+    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    
+    update_data = todo_in.dict(exclude_unset=True)
+    for field, value in update_data.items():
+        setattr(db_todo, field, value)
+    
+    db.add(db_todo)
+    db.commit()
+    db.refresh(db_todo)
+    return db_todo
+
+@todos_router.delete("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(todo_id: int, db: Session = Depends(get_db)):
+    """Delete a todo item"""
+    db_todo = db.query(TodoModel).filter(TodoModel.id == todo_id).first()
+    if db_todo is None:
+        raise HTTPException(status_code=404, detail="Todo not found")
+    
+    db.delete(db_todo)
+    db.commit()
+    return None

app/core/config.py

@@ -0,0 +1,14 @@
+from pathlib import Path
+from pydantic_settings import BaseSettings
+
+class Settings(BaseSettings):
+    APP_NAME: str = "Simple Todo App"
+    
+    # Database
+    DB_DIR: Path = Path("/app") / "storage" / "db"
+    
+    class Config:
+        env_file = ".env"
+        case_sensitive = True
+
+settings = Settings()

app/db/session.py

@@ -0,0 +1,29 @@
+from pathlib import Path
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+# Ensure DB directory exists
+settings.DB_DIR.mkdir(parents=True, exist_ok=True)
+
+SQLALCHEMY_DATABASE_URL = f"sqlite:///{settings.DB_DIR}/db.sqlite"
+
+engine = create_engine(
+    SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+Base = declarative_base()
+
+def get_db():
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+def create_tables():
+    Base.metadata.create_all(bind=engine)

app/models/__init__.py

@@ -0,0 +1 @@
+from app.models.todo import Todo

app/models/todo.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime, func
+from sqlalchemy.ext.declarative import declared_attr
+from sqlalchemy.ext.declarative import declarative_base
+
+from app.db.session import Base
+
+class Todo(Base):
+    __tablename__ = "todos"
+    
+    id = Column(Integer, primary_key=True, index=True)
+    title = Column(String, index=True)
+    description = Column(String, nullable=True)
+    completed = Column(Boolean, default=False)
+    created_at = Column(DateTime, server_default=func.now())
+    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())

app/schemas/__init__.py

@@ -0,0 +1 @@
+from app.schemas.todo import Todo, TodoCreate, TodoUpdate, TodoInDB

app/schemas/todo.py

@@ -0,0 +1,27 @@
+from datetime import datetime
+from typing import Optional
+from pydantic import BaseModel, Field
+
+class TodoBase(BaseModel):
+    title: str = Field(..., min_length=1, max_length=100)
+    description: Optional[str] = Field(None, max_length=500)
+    completed: bool = False
+
+class TodoCreate(TodoBase):
+    pass
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = Field(None, min_length=1, max_length=100)
+    description: Optional[str] = Field(None, max_length=500)
+    completed: Optional[bool] = None
+
+class TodoInDB(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        orm_mode = True
+
+class Todo(TodoInDB):
+    pass

main.py

@@ -0,0 +1,25 @@
+import uvicorn
+from fastapi import FastAPI
+from app.api.routers import todos_router
+from app.core.config import settings
+from app.db.session import create_tables
+
+app = FastAPI(
+    title=settings.APP_NAME,
+    description="A simple TODO application API",
+    version="0.1.0",
+)
+
+app.include_router(todos_router, prefix="/api")
+
+@app.get("/health", tags=["Health"])
+async def health_check():
+    """Health check endpoint"""
+    return {"status": "ok"}
+
+@app.on_event("startup")
+async def startup_event():
+    create_tables()
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

requirements.txt

@@ -0,0 +1,7 @@
+fastapi==0.104.1
+uvicorn==0.23.2
+pydantic==2.4.2
+pydantic-settings==2.0.3
+sqlalchemy==2.0.22
+alembic==1.12.1
+python-dotenv==1.0.0