Create Todo application with FastAPI and SQLAlchemy

Generated with and Co-Authored by [BackendIM](https://backend.im)

README.md

@@ -1,3 +1,77 @@
-# FastAPI Application
+# Todo Application API
 
-This is a FastAPI application bootstrapped by BackendIM, the AI-powered backend generation platform.
+A Todo application backend built with Python, FastAPI, and SQLAlchemy.
+
+## Features
+
+- Create, read, update, and delete todo items
+- List all todos with pagination
+- Persistent storage using SQLite
+- API documentation with Swagger UI and ReDoc
+
+## Tech Stack
+
+- **FastAPI**: High-performance web framework for building APIs
+- **SQLAlchemy**: SQL toolkit and ORM
+- **Alembic**: Database migration tool
+- **Pydantic**: Data validation and settings management
+- **SQLite**: Lightweight disk-based database
+- **Uvicorn**: ASGI server
+
+## Project Structure
+
+```
+.
+├── alembic/                  # Database migrations
+│   └── versions/             # Migration scripts
+├── app/                      # Application code
+│   ├── api/                  # API endpoints
+│   │   └── endpoints/        # API route handlers
+│   ├── core/                 # Core functionality
+│   ├── db/                   # Database
+│   │   └── repositories/     # Database repositories
+│   ├── models/               # SQLAlchemy models
+│   └── schemas/              # Pydantic schemas
+├── alembic.ini               # Alembic config
+├── main.py                   # Application entry point
+└── requirements.txt          # Dependencies
+```
+
+## Getting Started
+
+### Prerequisites
+
+- Python 3.8+
+
+### Installation
+
+1. Clone the repository
+2. Install the dependencies:
+   ```
+   pip install -r requirements.txt
+   ```
+
+3. Run database migrations:
+   ```
+   alembic upgrade head
+   ```
+
+4. Start the server:
+   ```
+   uvicorn main:app --reload
+   ```
+
+### API Documentation
+
+Once the server is running, you can access:
+
+- Swagger UI: http://localhost:8000/docs
+- ReDoc: http://localhost:8000/redoc
+
+## API Endpoints
+
+- `GET /api/v1/todos`: List all todos
+- `POST /api/v1/todos`: Create a new todo
+- `GET /api/v1/todos/{todo_id}`: Get a specific todo
+- `PUT /api/v1/todos/{todo_id}`: Update a specific todo
+- `DELETE /api/v1/todos/{todo_id}`: Delete a specific todo

alembic.ini

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+# 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
+
+# sys.path path, will be prepended to sys.path if present.
+# defaults to the current working directory.
+prepend_sys_path = .
+
+# timezone to use when rendering the date within the migration file
+# as well as the filename.
+# If specified, requires the python-dateutil library that can be
+# installed by adding `alembic[tz]` to the pip requirements
+# 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.
+# The path separator used here should be the separator specified by "version_path_separator" below.
+# version_locations = %(here)s/bar:%(here)s/bat:alembic/versions
+
+# version path separator; As mentioned above, this is the character used to split
+# version_locations. The default within new alembic.ini files is "os", which uses os.pathsep.
+# If this key is omitted entirely, it falls back to the legacy behavior of splitting on spaces and/or commas.
+# Valid values for version_path_separator are:
+#
+# version_path_separator = :
+# version_path_separator = ;
+# version_path_separator = space
+version_path_separator = os  # Use os.pathsep. Default configuration used for new projects.
+
+# the output encoding used when revision files
+# are written from script.py.mako
+# output_encoding = utf-8
+
+sqlalchemy.url = driver://user:pass@localhost/dbname
+
+
+[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 REVISION_SCRIPT_FILENAME
+
+# 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 +1,81 @@
+from logging.config import fileConfig
+
+from alembic import context
+from sqlalchemy import engine_from_config, pool
+
+from app.core.config import settings
+from app.db.base import Base
+
+# 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.
+fileConfig(config.config_file_name)
+
+# add your model's MetaData object here
+# for 'autogenerate' support
+# from myapp import mymodel
+# target_metadata = mymodel.Base.metadata
+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.
+
+# Override sqlalchemy.url value from external source
+config.set_main_option("sqlalchemy.url", settings.SQLALCHEMY_DATABASE_URL)
+
+
+def run_migrations_offline():
+    """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():
+    """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():
+    ${upgrades if upgrades else "pass"}
+
+
+def downgrade():
+    ${downgrades if downgrades else "pass"}

alembic/versions/b28d5d6a1a82_create_todo_table.py

@@ -0,0 +1,37 @@
+"""create todo table
+
+Revision ID: b28d5d6a1a82
+Revises: 
+Create Date: 2025-05-11
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'b28d5d6a1a82'
+down_revision = None
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    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(), default=False),
+        sa.Column('created_at', sa.DateTime(timezone=True), server_default=sa.func.now()),
+        sa.Column('updated_at', sa.DateTime(timezone=True), server_default=sa.func.now(), onupdate=sa.func.now()),
+        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)
+
+
+def downgrade():
+    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')

app/api/endpoints/todos.py

@@ -0,0 +1,82 @@
+from typing import Any, List
+
+from fastapi import APIRouter, Depends, HTTPException, status
+from sqlalchemy.orm import Session
+
+from app.core.deps import get_db
+from app.db.repositories.todo import todo_repository
+from app.schemas.todo import Todo, TodoCreate, TodoList, TodoUpdate
+
+router = APIRouter()
+
+
+@router.get("/", response_model=TodoList)
+def list_todos(
+    skip: int = 0, limit: int = 100, db: Session = Depends(get_db)
+) -> Any:
+    """
+    Retrieve all todos.
+    """
+    todos = todo_repository.get_todos(db, skip=skip, limit=limit)
+    count = todo_repository.get_todo_count(db)
+    return {"items": todos, "count": count}
+
+
+@router.post("/", response_model=Todo, status_code=status.HTTP_201_CREATED)
+def create_todo(
+    todo_in: TodoCreate, db: Session = Depends(get_db)
+) -> Any:
+    """
+    Create new todo.
+    """
+    todo = todo_repository.create_todo(db, todo_in)
+    return todo
+
+
+@router.get("/{todo_id}", response_model=Todo)
+def get_todo(
+    todo_id: int, db: Session = Depends(get_db)
+) -> Any:
+    """
+    Get todo by ID.
+    """
+    todo = todo_repository.get_todo(db, todo_id=todo_id)
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Todo not found"
+        )
+    return todo
+
+
+@router.put("/{todo_id}", response_model=Todo)
+def update_todo(
+    todo_id: int, todo_in: TodoUpdate, db: Session = Depends(get_db)
+) -> Any:
+    """
+    Update a todo.
+    """
+    todo = todo_repository.get_todo(db, todo_id=todo_id)
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Todo not found"
+        )
+    todo = todo_repository.update_todo(db, db_obj=todo, obj_in=todo_in)
+    return todo
+
+
+@router.delete("/{todo_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_todo(
+    todo_id: int, db: Session = Depends(get_db)
+) -> None:
+    """
+    Delete a todo.
+    """
+    todo = todo_repository.get_todo(db, todo_id=todo_id)
+    if not todo:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail="Todo not found"
+        )
+    todo_repository.delete_todo(db, todo_id=todo_id)

app/api/routes.py

@@ -0,0 +1,6 @@
+from fastapi import APIRouter
+
+from app.api.endpoints import todos
+
+router = APIRouter()
+router.include_router(todos.router, prefix="/todos", tags=["todos"])

app/core/config.py

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+from pathlib import Path
+from pydantic_settings import BaseSettings
+
+BASE_DIR = Path(__file__).resolve().parent.parent.parent
+
+
+class Settings(BaseSettings):
+    PROJECT_NAME: str = "Todo Application"
+    API_V1_STR: str = "/api/v1"
+
+    # Database
+    DB_DIR = BASE_DIR.parent / "storage" / "db"
+    DB_DIR.mkdir(parents=True, exist_ok=True)
+    SQLALCHEMY_DATABASE_URL: str = f"sqlite:///{DB_DIR}/db.sqlite"
+
+
+settings = Settings()

app/core/deps.py

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+from typing import Generator
+
+from app.db.session import SessionLocal
+
+
+def get_db() -> Generator:
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()

app/db/base.py

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+# Import all models here for Alembic to detect
+from app.models.todo import Todo

app/db/repositories/todo.py

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+from typing import List, Optional
+from sqlalchemy.orm import Session
+
+from app.models.todo import Todo
+from app.schemas.todo import TodoCreate, TodoUpdate
+
+
+class TodoRepository:
+    def get_todos(self, db: Session, skip: int = 0, limit: int = 100) -> List[Todo]:
+        return db.query(Todo).offset(skip).limit(limit).all()
+    
+    def get_todo_count(self, db: Session) -> int:
+        return db.query(Todo).count()
+    
+    def get_todo(self, db: Session, todo_id: int) -> Optional[Todo]:
+        return db.query(Todo).filter(Todo.id == todo_id).first()
+    
+    def create_todo(self, db: Session, todo_in: TodoCreate) -> Todo:
+        db_todo = Todo(
+            title=todo_in.title,
+            description=todo_in.description,
+            completed=todo_in.completed
+        )
+        db.add(db_todo)
+        db.commit()
+        db.refresh(db_todo)
+        return db_todo
+    
+    def update_todo(
+        self, db: Session, *, db_obj: Todo, obj_in: TodoUpdate
+    ) -> Todo:
+        update_data = obj_in.model_dump(exclude_unset=True)
+        for field in update_data:
+            setattr(db_obj, field, update_data[field])
+        db.add(db_obj)
+        db.commit()
+        db.refresh(db_obj)
+        return db_obj
+    
+    def delete_todo(self, db: Session, *, todo_id: int) -> None:
+        todo = db.query(Todo).filter(Todo.id == todo_id).first()
+        if todo:
+            db.delete(todo)
+            db.commit()
+
+
+todo_repository = TodoRepository()

app/db/session.py

@@ -0,0 +1,14 @@
+from sqlalchemy import create_engine
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import sessionmaker
+
+from app.core.config import settings
+
+engine = create_engine(
+    settings.SQLALCHEMY_DATABASE_URL,
+    connect_args={"check_same_thread": False}
+)
+
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+Base = declarative_base()

app/models/todo.py

@@ -0,0 +1,15 @@
+from sqlalchemy import Column, Integer, String, Boolean, DateTime
+from sqlalchemy.sql import func
+
+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(timezone=True), server_default=func.now())
+    updated_at = Column(DateTime(timezone=True), server_default=func.now(), onupdate=func.now())

app/schemas/todo.py

@@ -0,0 +1,38 @@
+from datetime import datetime
+from typing import Optional
+
+from pydantic import BaseModel
+
+
+class TodoBase(BaseModel):
+    title: str
+    description: Optional[str] = None
+    completed: bool = False
+
+
+class TodoCreate(TodoBase):
+    pass
+
+
+class TodoUpdate(BaseModel):
+    title: Optional[str] = None
+    description: Optional[str] = None
+    completed: Optional[bool] = None
+
+
+class TodoInDBBase(TodoBase):
+    id: int
+    created_at: datetime
+    updated_at: datetime
+
+    class Config:
+        from_attributes = True
+
+
+class Todo(TodoInDBBase):
+    pass
+
+
+class TodoList(BaseModel):
+    items: list[Todo]
+    count: int

main.py

@@ -0,0 +1,17 @@
+import uvicorn
+from fastapi import FastAPI
+from app.api.routes import router as api_router
+from app.core.config import settings
+
+app = FastAPI(
+    title=settings.PROJECT_NAME,
+    description="Todo Application API",
+    version="1.0.0",
+    docs_url="/docs",
+    redoc_url="/redoc",
+)
+
+app.include_router(api_router, prefix=settings.API_V1_STR)
+
+if __name__ == "__main__":
+    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)

requirements.txt

@@ -0,0 +1,6 @@
+fastapi==0.110.0
+pydantic==2.6.3
+sqlalchemy==2.0.29
+alembic==1.13.1
+uvicorn==0.27.1
+python-dotenv==1.0.1