agentic-studio/zipit/todo_new/prompts/3_coder_main.py.md

# 3 — Coder (coder) — main.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 — including stdlib (from datetime import date, etc.)
2. Import from other project files: from models import Todo, SessionLocal
3. NEVER use relative imports (from .models) — ALWAYS absolute: from models import ...
4. Pydantic schemas use different names than SQLAlchemy models: TodoCreate, TodoResponse (not Todo)
5. SQLAlchemy engine: create_engine(url, connect_args={"check_same_thread": False})
6. SessionLocal: sessionmaker(autocommit=False, autoflush=False, bind=engine)
7. FastAPI dependencies: def get_db(): db = SessionLocal(); try: yield db; finally: db.close()
8. Pydantic v2: use model_dump() not dict(), class Config: from_attributes = True
9. All CRUD endpoints: POST (201), GET list, GET by id, PUT, DELETE (204)

NEVER:
- Leave out any import (EVERY type you use must be imported)
- Use relative imports (from .models)
- Add explanations or comments
- Leave placeholder code or TODO comments
- Use Flask syntax (app.run) in FastAPI projects
- 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 — including stdlib (from datetime import date, etc.)
2. Import from other project files: from models import Todo, SessionLocal
3. NEVER use relative imports (from .models) — ALWAYS absolute: from models import ...
4. Pydantic schemas use different names than SQLAlchemy models: TodoCreate, TodoResponse (not Todo)
5. SQLAlchemy engine: create_engine(url, connect_args={"check_same_thread": False})
6. SessionLocal: sessionmaker(autocommit=False, autoflush=False, bind=engine)
7. FastAPI dependencies: def get_db(): db = SessionLocal(); try: yield db; finally: db.close()
8. Pydantic v2: use model_dump() not dict(), class Config: from_attributes = True
9. All CRUD endpoints: POST (201), GET list, GET by id, PUT, DELETE (204)

NEVER:
- Leave out any import (EVERY type you use must be imported)
- Use relative imports (from .models)
- Add explanations or comments
- Leave placeholder code or TODO comments
- Use Flask syntax (app.run) in FastAPI projects
- 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 main.py (for a different project, adapt to this one):
```
from fastapi import FastAPI, Depends, HTTPException
from sqlalchemy.orm import Session
from models import Base, engine, SessionLocal, Item
from schemas import ItemCreate, ItemResponse

Base.metadata.create_all(bind=engine)
app = FastAPI()

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

@app.post("/items/", response_model=ItemResponse, status_code=201)
def create_item(item: ItemCreate, db: Session = Depends(get_db)):
    db_item = Item(**item.model_dump())
    db.add(db_item)
    db.commit()
    db.refresh(db_item)
    return db_item

@app.get("/items/", response_model=list[ItemResponse])
def list_items(db: Session = Depends(get_db)):
    return db.query(Item).all()

@app.get("/items/{item_id}", response_model=ItemResponse)
def get_item(item_id: int, db: Session = Depends(get_db)):
    item = db.query(Item).filter(Item.id == item_id).first()
    if not item:
        raise HTTPException(status_code=404, detail="Not found")
    return item

@app.put("/items/{item_id}", response_model=ItemResponse)
def update_item(item_id: int, item: ItemCreate, db: Session = Depends(get_db)):
    db_item = db.query(Item).filter(Item.id == item_id).first()
    if not db_item:
        raise HTTPException(status_code=404, detail="Not found")
    for key, value in item.model_dump().items():
        setattr(db_item, key, value)
    db.commit()
    db.refresh(db_item)
    return db_item

@app.delete("/items/{item_id}", status_code=204)
def delete_item(item_id: int, db: Session = Depends(get_db)):
    db_item = db.query(Item).filter(Item.id == item_id).first()
    if not db_item:
        raise HTTPException(status_code=404, detail="Not found")
    db.delete(db_item)
    db.commit()
```

Already written files in THIS project:
--- models.py ---
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)

--- schemas.py ---
from pydantic import BaseModel

class TaskCreate(BaseModel):
    title: str
    description: str | None = None
    status: str = "pending"

class TaskResponse(TaskCreate):
    id: int

    class Config:
        from_attributes = True

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 "main.py" for THIS project: Todo-sovellus FastAPI + SQLite, CRUD-endpointit ja testit
Create the FastAPI app with all CRUD endpoints:
- Import from models.py and schemas.py (use exact class names)
- create_all(bind=engine) at module level
- get_db dependency with yield pattern
- POST (201), GET list, GET by id, PUT, DELETE (204)
- Use response_model for type safety
- Use model_dump() not dict() (Pydantic v2)
Adapt to the project requirements. Import from already written files. Write ONLY the code, no explanations.
```

## Tulos

```
from fastapi import FastAPI, Depends, HTTPException, Query
from sqlalchemy.orm import Session
from models import Base, engine, SessionLocal, Task
from schemas import TaskCreate, TaskResponse

Base.metadata.create_all(bind=engine)
app = FastAPI()

def get_db():
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()

@app.post("/tasks/", response_model=TaskResponse, status_code=201)
def create_task(task: TaskCreate, db: Session = Depends(get_db)):
    db_task = Task(**task.model_dump())
    db.add(db_task)
    db.commit()
    db.refresh(db_task)
    return db_task

@app.get("/tasks/", response_model=list[TaskResponse])
def list_tasks(status: str | None = Query(None), db: Session = Depends(get_db)):
    if status:
        tasks = db.query(Task).filter(Task.status == status).all()
    else:
        tasks = db.query(Task).all()
    return tasks

@app.get("/tasks/{task_id}", response_model=TaskResponse)
def get_task(task_id: int, db: Session = Depends(get_db)):
    task = db.query(Task).filter(Task.id == task_id).first()
    if not task:
        raise HTTPException(status_code=404, detail="Not found")
    return task

@app.put("/tasks/{task_id}", response_model=TaskResponse)
def update_task(task_id: int, task: TaskCreate, db: Session = Depends(get_db)):
    db_task = db.query(Task).filter(Task.id == task_id).first()
    if not db_task:
        raise HTTPException(status_code=404, detail="Not found")
    for key, value in task.model_dump().items():
        setattr(db_task, key, value)
    db.commit()
    db.refresh(db_task)
    return db_task

@app.delete("/tasks/{task_id}", status_code=204)
def delete_task(task_id: int, db: Session = Depends(get_db)):
    db_task = db.query(Task).filter(Task.id == task_id).first()
    if not db_task:
        raise HTTPException(status_code=404, detail="Not found")
    db.delete(db_task)
    db.commit()
```