# 1 — Data Engineer (data) — models.py

**Malli:** `qwen-coder`

## System Prompt

```
You are a database architect specializing in SQLAlchemy and relational databases.

YOUR RESPONSIBILITIES:
1. Design normalized database schemas with proper column types and constraints
2. Define SQLAlchemy models with __tablename__, primary keys, indexes, and relationships
3. Set up engine, SessionLocal, and Base in the same file (models.py)
4. Use String(length) not bare String for SQLite compatibility
5. Add nullable=False for required fields, unique=True where appropriate
6. Use Column(Integer, primary_key=True, index=True) for IDs
7. SQLite: create_engine(url, connect_args={"check_same_thread": False})

ENUM HANDLING (IMPORTANT):
- For status fields, use Column(String(20)) with a default value — simpler and SQLite-compatible
- Do NOT define Python Enum classes — use plain strings instead
- Example: status = Column(String(20), default="pending")

ALWAYS INCLUDE:
- from sqlalchemy import create_engine, Column, Integer, String
- from sqlalchemy.ext.declarative import declarative_base
- from sqlalchemy.orm import sessionmaker
- DATABASE_URL, engine, SessionLocal, Base
- create_engine with connect_args={"check_same_thread": False}
```

## Syöte

```
You are a database architect specializing in SQLAlchemy and relational databases.

YOUR RESPONSIBILITIES:
1. Design normalized database schemas with proper column types and constraints
2. Define SQLAlchemy models with __tablename__, primary keys, indexes, and relationships
3. Set up engine, SessionLocal, and Base in the same file (models.py)
4. Use String(length) not bare String for SQLite compatibility
5. Add nullable=False for required fields, unique=True where appropriate
6. Use Column(Integer, primary_key=True, index=True) for IDs
7. SQLite: create_engine(url, connect_args={"check_same_thread": False})

ENUM HANDLING (IMPORTANT):
- For status fields, use Column(String(20)) with a default value — simpler and SQLite-compatible
- Do NOT define Python Enum classes — use plain strings instead
- Example: status = Column(String(20), default="pending")

ALWAYS INCLUDE:
- from sqlalchemy import create_engine, Column, Integer, String
- from sqlalchemy.ext.declarative import declarative_base
- from sqlalchemy.orm import sessionmaker
- DATABASE_URL, engine, SessionLocal, Base
- create_engine with connect_args={"check_same_thread": False}

EXAMPLE of models.py (for a different project, adapt to this one):
```
from sqlalchemy import create_engine, Column, Integer, String
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker

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

class Item(Base):
    __tablename__ = "items"
    id = Column(Integer, primary_key=True, index=True)
    name = Column(String(100), nullable=False)
    description = Column(String(500))
```

PROJECT REQUIREMENTS (from product owner):
### PROJECT NAME: Todo-App

### GOAL:
Create a simple task manager application for individuals to keep track of their daily tasks.

### CORE FEATURES:
1. **Add Task**: Users can add new tasks with title and description.
2. **View Tasks**: Users can see all their tasks in a list.
3. **Edit Task**: Users can update the details of an existing task.
4. **Delete Task**: Users can remove tasks they no longer need.
5. **Mark as Complete**: Users can mark tasks as completed.
6. **Filter Tasks**: Users can filter tasks by status (e.g., pending, completed).
7. **Search Tasks**: Users can search for specific tasks using keywords in the title or description.

### DATA MODEL:
- **Tasks**
  - `id` (integer, primary key)
  - `title` (string, required)
  - `description` (text)
  - `status` (enum: "pending", "completed")
  - `created_at` (timestamp)

### API ENDPOINTS:
1. **GET /tasks**: Retrieve a list of all tasks.
2. **POST /tasks**: Create a new task with title, description, and status.
3. **PUT /tasks/{id}**: Update an existing task by ID.
4. **DELETE /tasks/{id}**: Delete a task by ID.
5. **GET /tasks/status/{status}**: Retrieve tasks filtered by status.

### CONSTRAINTS:
- Must use SQLite as the database.
- No authentication required for simplicity.

NOW write "models.py" for THIS project: Todo-sovellus FastAPI + SQLite, CRUD-endpointit ja testit
Define the SQLAlchemy model based on the project description. Always include:
- engine with check_same_thread=False for SQLite
- SessionLocal with autocommit=False
- Base = declarative_base()
- Model class with __tablename__, primary key, and fields
Adapt to the project requirements. Import from already written files. Write ONLY the code, no explanations.
```

## Tulos

```
from sqlalchemy import create_engine, Column, Integer, String, DateTime, Text
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import sessionmaker
from datetime import datetime

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 Task(Base):
    __tablename__ = "tasks"
    id = Column(Integer, primary_key=True, index=True)
    title = Column(String(100), nullable=False)
    description = Column(Text)
    status = Column(String(20), default="pending")
    created_at = Column(DateTime, default=datetime.utcnow)

Base.metadata.create_all(bind=engine)
```