# 2 — Coder (coder) — schemas.py

**Malli:** `qwen-coder`

## System Prompt

```
You are an expert Python developer. Write complete, production-ready code.

CRITICAL RULES:
1. Include ALL imports at the top of every file
2. Import from other project files: from models import User, SessionLocal
3. Pydantic schemas use different names than SQLAlchemy models: UserCreate, UserResponse (not User)
4. SQLAlchemy engine: create_engine(url, connect_args={"check_same_thread": False})
5. SessionLocal: sessionmaker(autocommit=False, autoflush=False, bind=engine)
6. FastAPI dependencies: def get_db(): db = SessionLocal(); try: yield db; finally: db.close()
7. Pydantic v2: use model_dump() not dict(), class Config: from_attributes = True
8. All CRUD endpoints: POST (201), GET list, GET by id, PUT, DELETE (204)

NEVER:
- Add explanations or comments like "# Add routes here"
- Leave placeholder code or TODO comments
- Use Flask syntax (app.run) in FastAPI projects
- Forget to import from other project files
- Use requirements.txt or Poetry — always use pyproject.toml with [project] format (PEP 621)
- Use pip install — use uv (e.g. uv run uvicorn main:app --reload)
```

## Syöte

```
You are an expert Python developer. Write complete, production-ready code.

CRITICAL RULES:
1. Include ALL imports at the top of every file
2. Import from other project files: from models import User, SessionLocal
3. Pydantic schemas use different names than SQLAlchemy models: UserCreate, UserResponse (not User)
4. SQLAlchemy engine: create_engine(url, connect_args={"check_same_thread": False})
5. SessionLocal: sessionmaker(autocommit=False, autoflush=False, bind=engine)
6. FastAPI dependencies: def get_db(): db = SessionLocal(); try: yield db; finally: db.close()
7. Pydantic v2: use model_dump() not dict(), class Config: from_attributes = True
8. All CRUD endpoints: POST (201), GET list, GET by id, PUT, DELETE (204)

NEVER:
- Add explanations or comments like "# Add routes here"
- Leave placeholder code or TODO comments
- Use Flask syntax (app.run) in FastAPI projects
- Forget to import from other project files
- Use requirements.txt or Poetry — always use pyproject.toml with [project] format (PEP 621)
- Use pip install — use uv (e.g. uv run uvicorn main:app --reload)

EXAMPLE of schemas.py (for a different project, adapt to this one):
```
from pydantic import BaseModel

class ItemCreate(BaseModel):
    name: str
    description: str | None = None

class ItemResponse(ItemCreate):
    id: int

    class Config:
        from_attributes = True
```

Already written files in THIS project:
--- models.py ---
from sqlalchemy import create_engine, Column, Integer, String, Date, Enum
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

DATABASE_URL = "sqlite:///./todo.db"
engine = create_engine(DATABASE_URL, connect_args={"check_same_thread": False})
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
Base = declarative_base()

class Todo(Base):
    __tablename__ = "todos"
    id = Column(Integer, primary_key=True, index=True)
    title = Column(String(100), nullable=False)
    description = Column(String(500))
    due_date = Column(Date, nullable=False)
    status = Column(Enum('pending', 'completed'), default='pending')

PROJECT REQUIREMENTS (from product owner):
1. **PROJECT NAME:** Todo-sovellus

2. **GOAL:** A simple task manager for individuals to keep track of their daily tasks and manage them efficiently.

3. **CORE FEATURES:**
   - Create new todos with title, description, due date.
   - Read/View all todos or a single todo by ID.
   - Update existing todos (title, description, status).
   - Delete completed or unnecessary todos.
   - Filter todos by status (e.g., pending, completed).

4. **DATA MODEL:**
   - Todo
     - id (integer, primary key)
     - title (string)
     - description (text)
     - due_date (date)
     - status (enum: 'pending', 'completed')

5. **API ENDPOINTS:**
   - GET /todos: Retrieve all todos.
   - GET /todos/{id}: Retrieve a single todo by ID.
   - POST /todos: Create a new todo.
   - PUT /todos/{id}: Update an existing todo.
   - DELETE /todos/{id}: Delete a todo.

6. **CONSTRAINTS:**
   - Must use SQLite as the database.
   - No authentication required for accessing endpoints.
   - Implement unit tests and integration tests to ensure functionality.

NOW write "schemas.py" for THIS project: Todo-sovellus FastAPI + SQLite, CRUD-endpointit ja testit
Create Pydantic schemas that match the SQLAlchemy model:
- Create schema: fields without id (user provides these)
- Response schema: inherits from Create, adds id
- Add class Config with from_attributes = True (required for SQLAlchemy ORM)
Adapt to the project requirements. Import from already written files. Write ONLY the code, no explanations.
```

## Tulos

```
from pydantic import BaseModel

class TodoCreate(BaseModel):
    title: str
    description: str | None = None
    due_date: date
    status: str = 'pending'

class TodoResponse(TodoCreate):
    id: int

    class Config:
        from_attributes = True
```